Saturday, November 30, 2013

Learning Curve Effect in Various Industries and Products




Ford Model T        1909 -23      0.29        87%
Integrated Circuits  1962-68       0.047      67%
Photovoltaic Cells   1971-2000  0.042      72%




Lean Manufacturing
By Wikipedians
PediaPress
page 144
http://books.google.co.in/books?id=n0qKUzfYbyUC


Kaizen Assembly: Designing, Constructing, and Managing a Lean Assembly Line - Book Information

Chris A. Ortiz
CRC Press, 26-Jun-2006 -  264 pages


Kaizen Assembly: Designing, Constructing, and Managing a Lean Assembly Line takes you step-by-step through an actual kaizen event. This approach demonstrates in detail the mindset, the processes, and the practical insight needed to transform your current assembly line into a world-class lean operation.

Chris Ortiz brings the experience of over 150 successful kaizen events to the pages of this unique guide. Using clear, succinct, and unambiguous language rather than more general and esoteric terms found in other books, he explains how to implement waste reduction, 5S, time and motion studies, line balancing, quality-at-the-source, visual management, and workstation and assembly line design. Taking a unique approach, the book follows an example of the assembly process for an electric bike including illustrations of nearly every step along the way. Ortiz even includes the most valuable teaching tool of all: past mistakes, how they were overcome, and how to identify and avoid them.

Providing expert guidance that will last long after the consultants have left, Kaizen Assembly supplies the tools you need to make kaizen and lean assembly a permanent fixture at the heart of the shop floor.


http://books.google.co.in/books?id=61Wr87UGAFAC

Friday, November 29, 2013

Capability Maturity Model for Industrial Engineering - Industrial Engineering Capability Maturity Model (IECMM)



Proposed by Narayana Rao K.V.S.S. (29 November 2013)

7. Taking responsibility for total costs of the company - Total Cost Industrial Engineering
6. Taking Responsibility for complete technology efficiency engineering
5. Doing Operation Research Studies and Statistical Studies to reduce variation and optimize system/process  variables
4. Study of complete method/process and improving the method/process (Methods Efficiency Engineering)
3. Motion Study and improving the motion pattern of the operator and training him
2. Training Operators to do the activity in standard time
1. Time Study for a specified process and Standard Time Setting.




Industrial Engineering Capability Maturity Model (IECMM)
Posted in http://www.xzbu.com/3/view-3385415.htm (22.8.2012)

L1 (Initial stage): Some individuals in the company are implementing IE projects. The results depend on the individual's ability to implement in. In the initial stage, IE process  is unpredictable.   

L2 (Repeatable): IE awareness has increased. There is a procedure to implement IE. The new IE project can refer to past experience in similar projects which are planned and managed. Because IE project planning and tracking is stable and is able to repeat the success of previous experience.

L3 (Defined Level): IE  management has been standardized.  Establishment of clear responsibilities for the  IE management is made. The whole enterprise activities undertaken by IE Standard procedure has been documented. In a defined level of enterprise,  IE process and quality can be summarized as "standard and consistent." The process of project activities of either IE or IE management activities are stable and repeatable.   

L4 (Managed level): For IE process results and activities, quantitative targets are set. All IE activities and  projects are measured and analyzed and appropriate precautions are taken to maximize benefits. In the management-level,  enterprise IE process and quality can be summarized as "predictable", the process can be measured and controlled within an acceptable range of variation.   


L5 (Optimization level): Enterprise is a now in  dynamic self-improvement stage. The entire company is committed to continuous process improvement. At optimization level of the enterprise, the basic characteristics of IE process and quality can be summarized as "continuous improvement."


The model in Chinese Language


工业工程能力成熟度模型(IECMM)
(pronunciation - Gōngyè gōngchéng nénglì chéngshú dù móxíng)

L1(初始级):企业一般不能提供开展和维持IE活动的稳定的环境,IE项目的实施是临时的,实施的结果依赖于个人的能力。处于初始级,IE过程和产品质量是不可预测的。

Qǐyè yībān bùnéng tígōng kāizhǎn hé wéichí IE huódòng de wěndìng de huánjìng,IE xiàngmù dì shíshī shì línshí de, shíshī de jiéguǒ yīlài yú gèrén de nénglì. Chǔyú chūshǐ jí,IE guòchéng hé chǎnpǐn zhí liàng shì bùkě yùcè de.

  L2(可重复级):企业IE意识有了提高,在局部范围内建立了实施IE的规程,新的IE项目可以参考以往类似项目的经验进行策划和管理。因为IE项目的策划和跟踪是稳定的,能重复以前的成功经验,因此处于该级别的企业的IE过程可概况为“有纪律的”。

Qǐyè IE yìshí yǒule tígāo, zài júbù fànwéi nèi jiànlìle shíshī IE de guīchéng, xīn de IE xiàngmù kěyǐ cānkǎo yǐwǎng lèisì xiàngmù dì jīngyàn jìnxíng cèhuà hé guǎnlǐ. Yīnwèi IE xiàngmù dì cèhuà hé gēnzōng shì wěndìng de, néng chóngfù yǐqián de chénggōng jīngyàn, yīncǐ chǔyú gāi jíbié de qǐyè de IE guòchéng kě gàikuàng wèi “yǒu jìlǜ de”.




  L3(已定义级):企业IE管理已规范化,有完善的IE管理制度,设立了IE管理机构并明确职责,对IE管理及如何实施IE进行了系统的阐述,整个企业的IE活动的开展的标准过程已文档化。处于已定义级的企业的IE过程和产品质量可概括为“标准的和一致的”,无论是IE项目活动过程还是IE管理活动,都是稳定且可重复的。


Qǐyè IE guǎnlǐ yǐ guīfànhuà, yǒu wánshàn de IE guǎnlǐ zhìdù, shèlìle IE guǎnlǐ jīgòu bìng míngquè zhízé, duì IE guǎnlǐ jí rúhé shíshī IE jìnxíngle xìtǒng de chǎnshù, zhěnggè qǐyè de IE huódòng de kāizhǎn de biāozhǔn guòchéng yǐ wéndàng huà. Chǔyú yǐ dìngyì jí de qǐyè de IE guòchéng hé chǎnpǐn zhí liàng kě gàikuò wèi “biāozhǔn dì hé yīzhì de”, wúlùn shì IE xiàngmù huódòng guòchéng háishì IE guǎnlǐ huódòng, dōu shì wěndìng qiě kě chóngfù de.

  L4(已管理级):企业对IE活动的成果以及活动过程,都设置了定量的目标,对IE所有项目的重要活动进行度量,并进行分析及采取相应的预防措施。处于已管理级的企业IE过程和产品质量可概括为“可预测的”,过程是已测量的并能控制在可接受的变化范围内。


Qǐyè duì IE huódòng de chéngguǒ yǐjí huódòng guòchéng, dōu shèzhìle dìngliàng de mùbiāo, duì IE suǒyǒu qǐng mù dì zhòngyào huódòng jìnxíng dùliàng, bìng jìn háng fēnxī jí cǎiqǔ xiāngyìng de yùfáng cuòshī. Chǔyú yǐ guǎnlǐ jí de qǐyè IE guòchéng hé chǎnpǐn zhí liàng kě gàikuò wèi “kě yùcè de”, guòchéng shì yǐ cèliáng de bìng néng kòngzhì zài kě jiēshòu de biànhuà fànwéi nèi.

  L5(优化级):企业是一种动态的自我完善的管理,整个企业致力于持续的过程改进。处于优化级的企业,IE过程和产品质量的基本特征可概括为“持续改进”。

Qǐyè shì yī zhǒng dòngtài de zìwǒ wánshàn de guǎnlǐ, zhěnggè qǐyè zhìlì yú chíxù de guòchéng gǎijìn. Chǔyú yōuhuà jí de qǐyè,IE guòchéng hé chǎnpǐn zhí liàng de jīběn tèzhēng kě gàikuò wèi “chíxù gǎijìn”.


References given in the paper

[1]James R.Persse(王世锦,蔡愉祖 译).CMM实施指南[M].北京:机械工业出版社,2003。
  [2]邓世专.持续改进——CMM的精髓[EB/OL].北京:计世网(http://www2.ccw.com.cn/01/0119/b/0119b04_1.asp)。
  [3]韦海英.制造业企业工业工程能力成熟度模型(IE-CMM)研究[D].武汉:华中科技大学,2009。
  [4] Kim Caputo(于宏光,王家锋 等 译).CMM实施与软件过程改进[M].北京:机械工业出版社,2003。
  [5] 蔺宇,齐二石,史英杰.中国工业工程发展及其在制造业的应用研究[J].天津:科学学与科学技术管理, 2007(4)。
  [6]李欣.项目管理成熟度模型及其评估方法研究[D].西安:西北工业大学,2004。

Industrial Efficiency Engineering - Japanese - 産業効率エンジニアリング



Engineering an efficient environment that employs or SIMATIC existing controller, the TIA Portal framework for the new controller - SIMATIC STEP 7 version 12

http://www.automation.siemens.com/automation/jp/ja/automation_systems/automation-software/tiaportal/controller-sw-tia-portal/pages/default.aspx



Sangyō kōritsu enjiniaringu  - 産業効率エンジニアリング  - Industrial efficiency engineering






http://www.kpit.com/japan/product-engineering/solutions/engineering-design

http://www.engineer.jp/

Thursday, November 28, 2013

Cost Management Accounting

Robin Cooper wrote that Japanese companies maintained cost management accounting system to help them in managing and reducing costs. This is in addition to the traditional cost accounting system whose function was to provide inventory valuation information for financial accounting.

Kaizen costing is one such accounting activity.

Wednesday, November 27, 2013

Industrial Efficiency Engineering - A more descriptive title for Industrial Engineering

Toyota Production System is Just in Time Quality Production System

Toyota Production System can be described as Just in Time Quality Production System

TPS is JITQPS

Quality denotes customer acceptance and zero defects.
A defect in JIT system is very costly. Hence, good amount of effort goes into defect prevention activity in Toyota system.

What is the communication system used for ensuring just in time production. Customer has to inform the supplier what he wants and when he wants.

Shiego Shingo Described the basic principles behind TPS as

TPS – the principle behind the tool: 

“Provide the customer’s (internal and external customer) exact requirement immediately with perfect quality.”
(http://oldleandude.com/2011/01/25/shigeo-shingo%E2%80%99s-revolution/  )






________________________________________________

Came across the interesting blog 27.11.2013

Bruce Hamilton's Blog
http://oldleandude.com/

Blogs recommened by Bruce

_____________

http://www.aleanjourney.com/

http://blog.maskell.com/

http://leanthinkingnetwork.org/2011/11/02/hello-welcome/

http://gotboondoggle.blogspot.in/

http://michelbaudin.com/

http://thinkingpeoplesystem.wordpress.com/

http://www.leanblog.org/

http://jefffuchs.wordpress.com/

http://etmmfg.com/blog
_____________
_____________

Tuesday, November 26, 2013

combined waterjet and plasma on the same CNC machine



One of the things you might notice after looking at the above list is that waterjet and plasma fit together very nicely, each processes advantages nicely cancelling the other’s disadvantage. So these two cutting processes fit nicely together, giving a machine a very wide range of capabilities for processing almost any material.

But the biggest reason for the waterjet-plasma combination is the cost to produce parts. Many parts produced from steel plate require high precision in some areas, but not on the entire part. If you purchase a waterjet cutting machine, you have to cut the entire part using waterjet. If your competitor down the street buys a waterjet-plasma combo, he could produce the same part for less than half the cost! By combining the speed of plasma with the accuracy of waterjet, you can dramatically reduce the time and cost to cut most typical parts for metal fabrication.

http://www.esab-cutting.com/the-cnc-cutting-blog/waterjet-cutting/why-combine-waterjet-and-plasma-on-the-same-cnc-machine.html

Application of motion economy Principles to Jig and Fixture Design

 Application of motion economy Principles to Jig and Fixture Desigm

"A Jig holds parts in an exact position and guides the tool that works on them.""A Fixture is a less accurate device for holding parts which would otherwise have to be held in one hand while the other worked on them."

The designer's object in providing jigs and fixtures is primarily accuracy in machining or assembly.  Principles of motion economy are not made use of . Often, opening and closing them or positioning the workplace calls for more movements on the part of the operative than are strictly necessary. For example, a spanner may have to be used to tighten a nut when a wing nut would be more suitable. Some points worth noting are:

1.Clamps should be as simple to operate as possible and should not have to be screwed unless thisis essential-for accuracy of positioning. If two clamps are required they should be designed for use by the right and left hand sat the same time.

2. The design of the jig should be such that both hands can load parts into it with a minimum of obstruction. There should be no obstruction between the point of entry and the point from whichthe material is obtained.

3. The action of unclamping a jig should at the same time eject the part, so that the additionalmovements are not required to take part out of the jig.

4. Where possible on small assembly work‟ fixtures for a part which does not allow of two
-bandedworking should be made to take two parts, with sufficient space between them to allow both bands towork easily.

5. In some cases jigs are made to take several small parts. This may save loading time if several partscan be clamped in position as quickly as one.

6. The work-study man should not ignore machine jigs and fixtures such as milling jigs. A great deal of time and power is often wasted on milling machines owing to the fact that parts are milled one at a time when it may be quite feasible to mill two -or more at once.

7. If spring-loaded disappearing pins are used to position components, attention should be given totheir strength of construction. Unless the design is robust such devices tend to function well for awhile but then have to be repaired or redesigned.

8. In introducing a component into a jig it is important to ensure that the operator should be able to see what he is doing at all stages; this should be checked before any design is accepted. The recording techniques of two-handed process chart and multiple activity charts proves very useful in improvement studies of work place layout. In certain type of operations and particularly those with very short cycles which are repeated thousands of times (such as sweet packing or electronic assembly). It may be required to go into greater details of study to save on movement of hands and efforts and to develop best possible pattern of movement, thus enabling the operator to perform the operation repeatedly with a minimum of effort and fatigue.

The techniques used for this purpose frequently make use of filming and are known as 'Micro motion Study'

Source:
http://www.academia.edu/4932719/APPLICATI_ONS_OF_PRINCIPLES_OF_MOTION_ECONOMY_Y_2013_Wubshet_Abide_BAHIR_DAR_UNIVERSIT_Y_INSTITUTE

Jig and Fixture Design Manual - Erik Karl Henriksen - 1973 - Book Information



Written for the experienced engineer as well as the student, this comprehensive reference presents the fundamental aspects of jig and fixture design in a readable manner.

http://books.google.co.in/books?id=OX9hspFzRAsC

Chapter 22 Economics of Jigs and Fixtures

Foot Operated Machines - Jigs - Fixtures



FOOT PEDAL OPERATED SHEARING MACHINES
http://www.jawfeng.com.tw/foot-pedal-operated-shearing-machines.html



Foot Operated Sealing Machines
http://www.sevanapackagingsystems.com/foot-operated-sealing-machines-1454558.html


DONA PAPER PLATE MAKING MACHINE: FOOT OPERATED
http://www.indiatoolsonline.com/machines/dona-plate-making-machine/foot-operated-dona-plate-making-machine-detail

A very user friendly foot operated machine, low priced and dedicated to fix hangers as well as hinges for strut backs!
http://www.cassese.com/eng/multifix/cassese_mf10.html

Foot Operated Machine

We offer Foot Operated Machines, which are manufactured for optimum utility. Ideally designed for convenient functioning, these machines are operated by foot-paddles. These machines are generally used for leak proof sealing of aluminum foil bag and paper metalized polyester, multi-laired bag and namkeen pouches.
http://www.inkjetprinter.co.in/foot-operated-machine-690694.html

Pedal Foot Operated Pepsi Machine
http://www.pouchpackingmachines.net/pedal-foot-operated-pepsi-machine--265842.html

Safety foot operated switch Fox
http://www.jokabsafety.com/products/control-devices/safety-foot-operated-switch/

Foot Operated Soap Stamping Machine
http://www.sakunengineers.in/foot-operated-soap-stamping-machine.html

Foot Operated Core Cutting Machine.
http://www.slittcoatengineers.com/foot-operated-core-cutting-machine.htm

Foot Operated Capper
http://www.fillingmachinesindia.com/foot-operated-capper.html
Interesting demonstration video in it. It can be made two handed operation by having two bottles capped in each cycle.


Monday, November 25, 2013

Sangyo Noritsu - Industrial Efficiency in Japan



Nihon Noritsu Kyokai  - Japanese Efficiency Association - Known as Japanese Management Association

Sangyo noritsu kenkyujo - Industrial Efficiency Institute

Sangyo noritsu kenkyujo - Industrial Efficiency Research Institute

noritsu zoshin,  -  “efficiency  increase”

Scientific Management - kagakuteki kanriho

industrial rationalization - sangyo gorika

productivity - seisansei

Human relations - ningen kankei

quality control - hinshitsu tosei

Total quality control - zenshateki hinshitsu kanri

拡がるIE視点  -
http://monoist.atmarkit.co.jp/mn/articles/1104/05/news001.html


Japan IE review magazine
http://www.j-ie.com/ie-review/backnumber/

Lean System Consultancy by H.B.Maynard - Accenture



http://www.hbmaynard.com/ClientArticles/CSUpdate4.asp


Early in 1999, Matthews Bronze and Maynard entered into a partnership. Matthews Bronze had a desire to improve manufacturing productivity and begin a Lean journey through the use of Pull-Through (Lean) Manufacturing techniques.

Matthews has realized the following improvements in the photopolymer operation:

61% increase in throughput
69% reduction in production response time
300% increase in value-added ratio
75% reduction in defective pieces


http://www.hbmaynard.com/CaseStudies/2004/YorkCasket03-31-04.asp

York Caskets to remain competitive  needed to reduce unit costs by 20 to 40 percent. To reach this goal, York partnered with H.B. Maynard and Company, Inc. for assistance in converting the wood casket plant to a Lean Continuous Flow operation.

The strategy recommended by Maynard was to first design a Lean Manufacturing system using sound industrial engineering tools, including value-stream analysis, work method design and work balancing using engineered time standards, and kanban-controlled work flow.

This initiative provided an immediate impact on York’s productivity. Shortly after implementing the changes, York saw a 20 percent reduction in labor hours per casket in the post-finish area. Defects were reduced by 48%. Production response time in the post-finish area was reduced dramatically, from three hours to one hour. In turn, the value added ratio increased from 19 percent to 50 percent.


Sunday, November 24, 2013

Lean Production - Toyota System - Womack, Jones, and Roos



Content in Chapter 3

Chapter 3. The Rise of Lean Production


Example of Lean Production


In American Companies, die changes required a full day. The American companies dedicated die presses to each part. To Ohno of Toyota, that was not the solution. He has to stamp all the parts he needed from only few press lines. Hence he decided to decrease the die change time and he went on decreasing the die change time to 3 minutes and he also eliminated the need for die change specialists. The operators only will change the die. In the process he made the unexpected discovery - it actually cost less per part to make small batches of stampings than to run off enormous lots (due to  small setup costs).

Making only a few parts before assembling them into a car cause stamping mistakes to show up instantly. It made the production people more concerned about quality and that eliminated defectives significantly. But to make the system a success, Ohno needed both an extremely skilled and a highly motivated work force. Workers have take the initiative to maintain quality production. Otherwise, the whole factory will come to a halt.

Ohno organized his assembly workers into teams. The teams were given a set of assembly steps, their piece of line and told to work together on how best to perform the necessary operations. They work under a team leader, who would do assembly tasks, as well as coordinate the team and would  fill in for any absent worker. In mass production plans there were foremen and utility workers used to take the place of absentees. Ohno next gave the teams the job of housekeeping, minor tool repair, and quality checking. Finally, he gave them responsibility for process improvement also. This continuous, incremental improvement process, kaizen in Japanese, took place in collaboration with the industrial engineers, who still existed in much small number.

Ohno reasoned that rework at the end of assembly due to finding errors in final inspection is a waste. He wanted even assembly workers to pass on the work only if it is defect free and in case there is a defect which they could not rectify, they can stop the line and take the time to rectify the defect even with the help of other workers. Also, problem solving through 5 Whys methods is also used to avoid recurrence of the problem. In the initial days of this practice, the line was stopped  many times and workers got frustrated, with practice, the stoppages decreased significantly. Today, in Toyota plants,  yields approach 100 percent. That is the line practically never stops.  The extra benefit due to this method was that quality of shipped cars steadily improved. You cannot build quality by inspection, you have to build quality at the production centers only.  Today, Toyota assembly plant have practically no rework areas and perform almost no rework on assembled cars. In contrast, mass-production plants devote 20 percent of plant area and 25 percent of their total hours of final-assembly effort to fixing mistakes. American buyers report that Toyota's vehicles have among the lowest number of defects of any in the world, comparable to the very best of the German luxury car producers, who devote  many hours of assembly effort to rectification.


Chapter 4. Running the Factory

Classic Lean Production - Description of  Toyota Takaoka Plant

Toyota Takaoka plant was started in 1966.

The army of indirect workers so visible in General Motors plant are not there. Practically every workers in the plant is adding value. Toyota believes in face-to-face communication and hence facilities are located close together.  Less than an hour's worth of inventory was next to each worker. The line is well balanced and every worker worked at the same pace. If a defective part was found, worker carefully tagged it and send to quality control area of replacement.  Five why method is followed for every defective piece found.  Every worker has facility to stop the line. But the line is rarely stopped. There is no rework area for the assembled cars. Almost every car was driven direct from the line to the boat or truck.

There were practically no buffer between paint and final assembly. There were no parts warehouses. The work place was harder but there was a sense of purposefulness.

Mass Production versus Lean Comparision

Gross assembly hour per car was only 18 hours in comparison to 40.7 in GM Famingham plant.

Takaoka was almost twice as productive, three times as accurate as Framingham, but uses only 60% space. Its parts inventory was only 2 hours in comparison to 2 days of GM plant. It is a revolution because the change/improvement was in many dimensions. Also, the line can be changed to a new model a few days only.

Getting to Lean

Important organizational features of lean plants are responsible for half of the overall performance difference among plants of the world. The other two are automation and manufacturability.

The truly lean plant has two key organizational features.

It transfers the maxium number of tasks and responsibilities to those workers actually adding value to the car on the line.

It has in place a system for detecting defects that quickly traces  every problem, once discovered, to its ultimate cause.

In a lean plant all information of plant are displayed on andon boards.  Every time something goes wrong in the plant, every employee knows it and any employee who knowns how to help runs to lend a helping hand.

It is the dynamic work team that is at the heart of the lean factory.  To build efficient teams number of steps are necessary.  Firsr workers, who are team members, need to be taught a wide variety of skills. - in fact, alla the jobs in their work group or team so that tasks can be rotated and workers fill in for each other. Apart from production jobs, workers have to acquire many additional skills: simple machine repair, quality checking, housekeeping, and materials-ordering. They need encouragement to think proactively to solve problems before they become serious.

The authors say that workers respond only when they feel management values skilled workers, makes sacrifices to retain them and is willing to delegate responsibility to them.

The tools used in lean production system as covered by various authors on lean system are consolidated in
Lean Production System Tools - Categorization - Industrial Engineering

Taiichi Ohno specially praises and appreciates the role of industrial engineering in making Toyota, a success.
Taiichi Ohno on Industrial Engineering - Toyota Style Industrial Engineering


Explanation of the Toyota Production System by Taiichi Ohno in the book on Toyota Production System - Summary
Toyota Production System - Origin and Development - Taiichi Ohno






Related Reading

http://www.toyotageorgetown.com/gbl.asp

http://www.toyota-global.com/company/history_of_toyota/75years/text/entering_the_automotive_business/chapter1/section4/item2.html

http://www.toyota.de/images/toyota_in_the_world2008_tcm281-893219.pdf

Operation Analysis - Plant Layout Analysis



As the result of detailed methods efficiency analysis, suggestions are likely to be advanced concerning the improvement of plant layout.

The arrangement of machines and other equipment in the best locations for economical manufacturing plays an important part in efficient plant operation.

As the principles of scientific management began to develop,  plant layout also received more
attention. In the course of time, certain principles were developed which were thought to conform with efficient plant operation. The most important of these were briefly as follows:

1. Haw material should come in at one end of the shop, and the finished product should emerge at the other end.

2. Aisles should be provided for transportation purposes and should be kept clear at all times.

3. Like machines should be grouped and arranged in straight lines or orderly rows.

4. Ample space should be provided around each machine for the placement of material.

The general appearance of layouts made in conformance with these principles was pleasing. A sense of orderliness and lack of crowding was attained, and it was felt for some time that work was done efficiently under such conditions.

More detailed studies,  however, have shown that such arrangements are far from satisfactory and that many inefficiencies exist. Material travels farther than necessary; too much valuable floor space is used for storage purposes ; there is a great deal of back travel; military lines cause unnecessary walking and make it impossible to couple machines; finally, too much labor is spent in moving material about. As the result of a
realization of these facts, a new set of principles has been evolved which may be stated as follows:

1. When material is laid aside at the end of one operation, it should be placed in the position at which it may best be picked up for the next operation.

2. The distance that the operator must move to obtain or to lay aside material should be reduced to a minimum.

3. Time spent by a machine making a cut under power feed is idle time as far as the operator is concerned.



These three principles have a profound influence on plant layout. When applied, they usually result in layouts that look as chaotic to the uninformed observer as the original layouts. They are anything but inefficient, however, as can be recognized from the fact that there are no piles of material standing about, that
there is very little material handling as a separate activity, and that one operator is often found to be operating more than one machine.

Types of Plant Layout. 


Process Grouping


Industrial plants are laid out in two different ways. First, all equipment for a given process may be
grouped together; that is, all milling machines may be located in one part of the department, all welding in another, and all assembly work in still another. Process or horizontal grouping has several advantages. Because all operators doing a given class of work are located together, supervision is easier. New workers
can observe experienced operators on similar jobs and can learn by observation. Material for repairs and servicing can be kept accessible in a near-by location. The appearance of a line-up of similar machines is pleasing. These reasons made process grouping popular throughout industry until fairly recent times.

The disadvantages of process grouping, however, became more and more apparent as detailed studies were made. It was seen that material handling would be greatly simplified if the machines and other equipment were placed in the order in which they were to be used in producing a given product. If, for example, a part
was drilled, milled, painted, and assembled, the provision of a drill press, a milling machine, a paint booth, and an assembly bench lined up in order would permit the product to be manufactured with a minimum of handling. Hence, a different type of layout known as " product" or " vertical " grouping was developed.

Product Grouping


Product grouping, of course, was always practiced in plants manufacturing a single standard product. The advantages were so obvious that equipment was arranged in the order in which it was used. In plants manufacturing a variety of products, however, the full possibilities of product grouping developed much
later. Some of these plants had individual products which were manufactured in large quantities. In order to reduce costs, these products were separated from miscellaneous work, usually primarily to set up a separate costing center which might be assigned a lower overhead or burden rate. When a single product was
segregated and the equipment for producing it was set up in a special space, the equipment was arranged in conformance with the flow of material throughout the process or, in other words, product grouping was practiced.

The advantages gained were so striking that the possibilities of segregating other products were quickly sought. Product grouping replaced process grouping wherever possible.

On miscellaneous work, product grouping is impractical, and therefore process grouping must be used. Even in such cases, however, it is possible to make layouts that conform to the three -principles mentioned above to a large extent.


It will be seen, therefore, that although there are two different types of plant layout, the principles of effective layout practice may be achieved with either type.

Collecting Layout Information. 


It is a relatively simple matter to make an efficient layout if the principles to which it should conform are clearly understood and if complete information is available regarding the product and the processes which it must undergo. If information is collected in the proper form, the layout may be said almost to make itself in a number of cases.

For layout purposes, the operation process chart is one of the most valuable tools available.

In approaching a layout study, an operation process chart should first be constructed. If the layout is for a miscellaneous line of work, operation process charts should be constructed for representative jobs. In addition, information should be collected regarding the floor space available, expected yearly and monthly
activity, and possibilities of greater production in the future. Samples of the product in various stages of completion will also be of assistance in visualizing the processes and the material-handling problem involved.

The time required to perform each operation should be care-fully determined. If no time study data are available, time studies should be taken if the operations are being performed, or careful estimates should be prepared. This information is of primary importance, for the allowed time multiplied by the pro-duction desired per day will determine the number of work stations that must be provided for each operation.

When all information has been collected, it should be arranged for convenient use. A floor plan of the available manufacturing space is first laid out to scale on a table, drawing board, or sheet of stiff cardboard. The operation process chart should be placed where it can be studied easily; that is, it should be tacked to the wall in front of the layout table or placed in some other con-venient position. The samples of the product should be lined up in the order of the process and placed where they may be glanced at from time to time.

Finally, all other data should be put in form for convenient reference.

The manner in which this may be done ;  Present- and expected-activity data are first given. Then each operation is considered in order. The number of work stations required is computed and recorded, and any special information that may have a bearing on the process is noted. The floor space occupied by each work station is ascertained and recorded.

Layout Templates. 


During the course of a layout study, many different arrangements of equipment will be considered. There-fore, it is desirable to prepare templates (representing each work station or piece of equipment) which may be shifted about readily as different arrangements are considered.

Templates are made to the same scale as the floor plan. The scale J4 inch = 1 foot is convenient for most layouts. Templates are commonly made from light cardboard or stiff drawing paper. They should represent the total floor space occupied by the equipment under extreme conditions. A milling machine, for example, should be represented with its table extended the maximum distance in each direction, and a screw machine should be shown with the maximum length of bar stock in place.

Sometimes, it may be desirable to show the space around the work station that is occupied by raw and finished material. If so, the space so occupied should be indicated by sectioning or color on the template. Different methods of handling material may be developed during the course of the layout study, and
therefore a distinction should be made between space occupied by equipment, which Is not subject to change, and space occupied by material.

A layout representation should be as clear as possible, for a number of different Individuals will examine it before it Is finally approved. Small models of the equipment placed on a drawing or other representation of the available floor space as shown by Fig. 94 undoubtedly present the clearest understanding of the
layout, but their preparation often consumes more time than is justified by the clearness gained. Photographs of equipment glued to the templates, as shown by Fig. 95, however, are comparatively easy to prepare and will add to the clearness of the layout. If photographs of a suitable size are not available, templates may be colorejl to distinguish among different types of equipment. If a layout when made has to be presented for
approval to executives who are not particularly familiar with the work, the adoption or rejection of the proposed layout may depend upon the clearness with which it is presented.

Making the Layout. 


The floor plan on which the layout is made may be a blank plan showing only the fixed features of the
floor space, such as columns, elevators, and -washrooms; or if only a minor revision is contemplated, it may show the present location of all equipment. If the latter, the present flow of material can be indicated by lines drawn between machines and equipment to show the path followed by material.

The study of a layout is more than a one-man job. One man can collect information and samples and prepare the floor plan and templates. He can study the problem and make the best initial arrangement that he can conceive. In order to get the benefit of suggestions from every possible source, however, he should then call in others and ask for criticism. The plant superintendent will view the problem from one angle, the foreman
in charge of the work from another, and the operators who do the work from still another. Their comments and suggestions should be encouraged, for the resulting layout will be much improved.

When a number of individuals are commenting on a layout, many revisions will be suggested. Tlie layout representation should be such, therefore, that it can be readily changed. At the outset, it may be inadvisable to fasten the templates in position in any way. If they are merely laid on the floor plan, they can be shifted about until a rough approximation of the desired arrangement is obtained. The templates must then be
located carefully with all aisles, material-storage spaces, conveyers, and so on, represented to scale. At this point, it becomes desirable to fasten the templates down in position so that they will not move. Thumbtacks, map pins, brads, staples, or rubber cement may be used. If desired, tacks or map pins with different colored heads may be used to represent different classes of equipment.

A layout bristling with pins is not an easy object to handle. Therefore, rubber cement may be preferable for securing templates to the layout. A small dab of cement should be put on the back of the template and the template stuck in position. While the cement is wet, the template may be slid about as it is being brought into exact position. The cement hardens quickly and will hold the template securely. If, however, it is desired to
remove the template, a slight pull will unstick it. The dried cement on the floor plan and on the template may be rubbed off with the finger, restoring them both to their original condition. In working with templates, a two-dimensional representation is obtained, and there is a tendency to overlook the fact that the actual manufacturing space is three-dimensional. Hence, everything may be placed on the floor while overhead space is unoccupied. This point should be kept in mind while making layouts, for material storage., conveyers, and so on, may often be placed above the floor level.

There is also a tendency to work with standard pieces of equipment and to try to make the process conform to the equipment rather than the equipment to the process. This is particularly true in connection with benches. Standard benches are used, and work is arranged on them as well as possible. Often, this
involves extra travel of material and extra movement of operators. Special benches are not costly, and they will often pay for themselves many times over. Figure 96 shows a portion of a special bench designed for a clock-motor assembly. The bench solved a difficult handling problem and permitted the work to
flow so that when material is laid aside by one operator it is in convenient position for grasping by the next.

When an arrangement is arrived at that seems satisfactory, the flow of material should be indicated to ascertain if the shortest possible movements are called for. Since the layout is always subject to revision, material flow may best be indicated by threads running from work, station to work station. If tacks or pins are used to hold the templates in position, the thread may be run from tack to tack quite easily. If templates are secured by rubber cement, a dab of cement in the proper places will fasten the thread in position.

Figure 97 shows a typical layout representation at the initial stage of the study. Several different products are manufactured, and, hence, different-colored threads are used to show the flow of different products.


When manufacturing is done on different floors, layouts of each floor may be made separately. They may then be shown in their relation to one another by placing them one above the other in a holding rack, as shown by Fig. 98. A rack of this kind occupies considerable space, however; if this is an important consideration, it may be more desirable to attach the layout representation to a wall with hinges. When the layout is not in use, it hangs on the wall, occupying little space, as shown by Fig. 99. When it is needed, any or all floor representations can be swung up in a position for study, as shown by Fig. 100.

Testing the Layout. When a given layout has been made in accordance with the foregoing methods and when it has been reviewed by all who are In a position to offer constructive comment, the layout at this point represents the best arrangement that those who have worked on it can visualize. If the layout has been made for a single product or for a relatively few products, it is probably safe to proceed with the physical arrangement of the equipment. If, however, the layout is designed for a variety of products, it is usually desirable to subject it to a more thorough test before beginning the physical moves.

The method of testing the flow of material by means of colored threads is useful at the initial stages of the layout, but if many different products are involved, the layout eventually becomes covered with a maze of interweaving threads, and it is difficult to recognize the flow of individual items.

A clearer method of testing the flow of materials is to secure a number of copies of the layout reproduced on a small scale. The original layout may be photographed, and a number of 8)4- by 11-inch prints obtained, or the layout may be redrawn to a smaller scale with a minimum amount of detail shown and a number of
blueprints made. Each small-scale reproduction may then be used to show by means of lines the flow of a single item. Since only one item is shown at a time, any backtracking or excessive travel is clearly revealed.

If the machines used in the production of a given part are marked and the number of pieces per hour obtainable from each machine are shown, a very clear understanding of the way the product will move through the layout will be gained, and possible difficulties can be foreseen. For example, assume that a part is
processed on two machines located side by side. If the production per hour is the same for each machine, the part will flow past this point without difficulty: If, however, the first machine produces at the rate of 600 pieces per hour and the second at the rate of 60 pieces per hour, parts are certain to pile up between
the two machines.

With this fact clearly established, the necessary action can be taken to minimize manufacturing difficulties. The recognition of the bottleneck will suggest its elimination by improving the method for the second operation or by providing additional machines. If it cannot be eliminated, then sufficient floor space
must be provided to hold the maximum amount of material that is likely to pile up ahead of the second machine.

Making the Physical Layout. 


When all parts flowing through the layout have been tested individually and all undesirable conditions have been reduced to a minimum, the physical layout can be started with the certainty that it will function reasonably well. At the same time, no matter how carefully a layout may be made on paper, it is quite likely that it will not be perfect. In working with a small scale, distances that require a step or two to cover
are so small that they may be overlooked. A two-dimensional representation does not portray clearly how the actual layout will look, and templates convey only a partial idea of the real nature





of the equipment. For these reasons, it is well to consider the
paper layout as being only tentative and to check it carefully as
the actual layout is made. At least one plant has established
the rule that when new layouts are made or old layouts revised,
no machine or piece of equipment is to be permanently fastened
in position until a few pieces have been manufactured. Most
equipment will operate for a while" even if it is not firmly anchored,
and by testing the layout in actual operation, opportunities for
minor improvements are frequently discovered.

Preserving Layouts. Changing conditions cause more or less
frequent layout revisions. Therefore, the layout representations
should be preserved for future use. Where changes in product
are frequent, as for example, in the automobile industry, layout
representations may be kept set up permanently so that they are
always available for study. In more static industries, the lay-
outs may be placed hi a dustproof container and stored until
wanted. A really clear layout representation takes some time
to prepare, and it is usually more economical to store it than to
make a new one the next time a revision is contemplated.

Full Knol Book - Method Study: Methods Efficiency Engineering - Knol Book

Saturday, November 23, 2013

Allotment of Work - Job to Operators - Issues



In some cases, material to be processed is placed near the work stations of a number of operators. The operators go to the material and themselves select the jobs they wish to do. This procedure involves a -minimum amount of supervision and clerical work, but it possesses certain serious disadvantages. As has
already been pointed out, some jobs are more desirable from the operator's standpoint than others. They may be easier or lighter or cleaner, or if time allowances are not accurate as is sometimes the case, some jobs may carry looser rates than others, thus permitting higher earnings for a given expenditure of effort.
Regardless of the reason, certain jobs are preferable to others; if the operators are allowed to pick their own jobs, friction is likely to develop. Those who have stronger characters or are physically superior are likely to get the best jobs, and the weaker must take what is left. The least desirable jobs will be slighted altogether as long as there is any other work to do, which causes these jobs to lag and become overdue.

Finally, there is no assurance that the operators will get the jobs for which they are best suited, considering the group as a whole. If the most skilled operator happens to be the strongest, he is likely to select all the easiest jobs, leaving the more difficult jobs to those who are not so well qualified to do them.

Where the group system is used, these difficulties are minimized, but principally because the group leader assumes a function of management and hands out the work to the members of his group. The group knows that sooner or later it will have to handle all jobs sent to it, and so there is less tendency to slight
undesirable work. In the interests of good performance as a group, the skilled men will do the more difficult jobs, leaving the easier tasks to the new or less skilled men. In short, the entire situation is changed; when the group system is used, the selection of jobs may be left to the workers themselves.

Another common procedure is to have all jobs handed out by the foreman. The foreman knows the work, and he knows his men. Therefore, he is in a good position to distribute the work so that it will be performed most effectively. The chief difficulty with this arrangement is that the modern foreman is so loaded
with duties and responsibilities that he often does not have time to plan his work properly. In moments of rush activity, instead of always having several jobs ahead of each operator, he is likely to assign jobs only when men run out of work. When a man comes to him for a job, he is likely to glance at the available
work and assign the first job he sees that he thinks the operator can do. It may not be the one best suited to the operator; perhaps even more important, it may not be the job that is most important from a delivery standpoint.

With regard to this last point, in order to get work through the shop on schedule, the planning or production department must work closely with the foreman. Usually, chasers or expediters call to the attention of the foreman the job that is required next. If there are only a few rush jobs, the foreman may be able to
have them completed as desired. In times of peak activity, however, when the shop is overloaded, all jobs become rush jobs. Each expediter has a long list of jobs to be completed at once. Considerable pressure is brought to bear upon the foreman to get out this job and that, and he is likely to find himself devoting
time to detailed production activities that could better be spent on taking steps to relieve the congestion.

In most up-to-date plants, the foreman is regarded as a very important man. He is called into conferences and meetings and often participates in educational programs. He is, therefore, away from his department at intervals and, if he has the responsibility of giving out jobs, must give out enough work to last until
he returns. If he is called away suddenly or is unexpectedly detained, operators will run out of work. Then they either lose considerable time and hence money which creates dissatisfaction, or they help themselves to another job. If this latter practice is countenanced in a time of emergency, there is a danger that it
will soon develop into a standard practice. If men get their own jobs, the foreman is relieved of a certain amount of work and, if he is otherwise overloaded, may tend to allow operators to select their work with increasing frequency, until all the advantages gained by having the foremen hand out work are lost.

The decisions with respect to the order in which jobs are to be put through the shop are made by the planning or production department. Since they know in what order jobs are wanted, it would, therefore, appear that a representative of this department should cooperate closely with the foreman in giving out the work. The foreman may specify the men who are to work on each job when the orders first reach his department, and a dispatch clerk may give the work to the assigned men in the order of its impor-
tance from a delivery standpoint. This arrangement is followed in a number of plants. Figure 66 shows a typical dispatching station under the control of the production department. Time tickets for each operation on each job are made out in a central planning department and are marked with the date the operation
should be completed. The dispatcher arranges these time tickets in his dispatch board. Each group of machines within the department is assigned a pocket hi the dispatch board, and each pocket has three subdivisions.

The time tickets are received considerably in advance of the material. They are first filed in a subdivision of the proper machine pockets called the "work ahead " division. The number of tickets in the "work ahead" divisions at any time gives a rough idea of the load on the shop. When material for a given job enters the department, the dispatcher Is notified. He then moves the time ticket for the first operation from the "work
ahead" division to the "work ready " division. The time tickets in the latter pocket then show the jobs that are actually ready to be worked upon. When an operator completes one job, he goes to the dispatcher's station and turns in the ticket for that job. The dispatcher then gives him another job by taking the time ticket from the "work ready" division and handing it to him. He selects always the ticket marked with the date nearest
to the current date and thus gets the work done in the desired order.

The rest of the system need not be described here, for it is desired principally to Indicate the manner in which jobs are handed out by a representative of the production department, thus relieving the foreman of this responsibility.

Source: Operation Analysis by Maynard

Normal and Maximum Working Areas - Work Place Layout


Figure 69 (Maynard)  is a sketch showing how the normal and maximum working areas for the hands in the horizontal plane are usually determined. In drawing the sketch, it is assumed that the worker is comfortably seated at or standing by his bench or table of proper height. His arms hang naturally from the shoulders. Placing his right hand on the near edge of the table approximately opposite his left side, he can sweep his right hand through the arc AMB. The area included between this arc and the edge of the table is generally said to represent the normal or most comfortable working area for the right hand.

The points along the arc AMB can be reached with a motion of the third class. To reach all other points within the area bounded by the arc, a fourth-class motion must be employed. It requires more time to make a fourth-class motion than it does to make a third-class motion of the same length. Hence, the arc AMB should receive preference when making layouts.

Even when third-class motions can be employed, motions of equal length cannot be made in the same length of time at all points, along the arc AMB. Motions are made most quickly near point A most slowly at point B. When motions must be made much beyond point M in the direction of point B y fatigue increases materially. The closer the hand approaches B } the more unnatural is the position that the arm must assume. In fact, if the elbow rests on the table, the point B cannot be reached at all.



The arc which bounds the maximum working area is traced
by the fingers when the arm, fully extended, is. pivoted about the
shoulder. For the right hand, this is arc CKD in Fig. 69. The
limitations discussed above do not apply to the maximum area.
All points can be reached by fourth-class motions, and motions
can be made as quickly in one section as in another. In posi-
tioning material within "this area, the chief concern should be to
keep the length of the movements at a minimum. If possible,
the section near BD should not be used. Besides involving
maximum travel, it requires a rather awkward and fatiguing
wrist motion to reach material located in bins anywhere except
at point D, or in other words, when the arm is not fully extended.

The above discussion applies equally to the areas used by the
left hand and arm.

In order to confine all motions to the third class, material
should be placed along the paths that the hands normally follow,
or along the arcs FLE and AMB of Fig. 69. The only point at
which the hands can work together without Involving the use of
shoulder motions to -change the position of the arms is the point J.
In reality, this is not a point but a small area, is determined

by the ^rist and finger motions that can be used without moving

the arms. , ,

In the vertical plane, the arc described by the fingers when a third-class movement Is made is the arc AB of Fig. 70, and the arc CD is the maximum arc made employing a fourth-class move- ment. These arcs determine
the efficient placement of
materials in the vertical plane.
When positioning tools that
are suspended above the work
area, care should be taken to
locate them within the sphere
which would be generated if
the arc CD, Fig. 70, were to be
rotated about the body of the
operator as an axis. If no
other equipment or material
interferes, the tools should be

located On the Sphere which
WQU ^ b e generated by similarly

rotating the arc AB ; but in any
case, they should be located so that they can be reached without
the necessity of employing body movements.

Methods Efficiency Engineering Studies - Detailed to Brief


The more detailed the study, "the greater the amount of time required to make it. With any study, the savings effected must equal or exceed the cost of making the study if the expenditure is to be justified from an economic standpoint.

Type A.

Written job analysis using one or more types of process charts and
analysis sheets.
Motion study employing motion pictures.
Motion time study.
Standardization including motion-picture training.
Time study.

Type B

Written job analysis using analysis sheets.
Motion study by analysis and observation.
Standardization including written instructions.
Time study.

Type C
Mental job analysis.
Standardization including verbal instructions.
Time study.

Type D

Written job analysis of class of work using process charts and analysis
sheets for analysis of representative jobs.
Motion study of representative jobs, usually employing motion
pictures to determine best methods.
Standardization including written instructions.
Time study.
Time formula.

Type E

Mental job analysis during general survey of work.
Motion study by analysis and observation during general survey.
Standardization.
Time study.
Time formula.

Type F

Standard data.

Types A, B, and C are applied particularly to individual jobs. Types D and E are applied to classes of work comprised of similar jobs, and type F is applied to either individual jobs or classes of work where quantities are very small.

The kind and the amount of study that are economically justified on any job or class of work are determined by three principal factors, namely, the repetitiveness of the job, the man-machine content, and the expected life of the job.


Source: Operation Analysis, Chapters 4 and 5, Maynard)

Behavioral Aspects of Industrial Engineering



Occasionally, ideas occur which appear to possess advantages to the originator other than those which can be measured in dollars and cents. In presenting suggestions of this nature, advantages and disadvantages should be presented in tabulated form, so that a decision can be quickly made.

Ideas of this kind are more subject to rejection than those which show definite money savings. Perhaps the advantages to be gained are so largely theoretical that a busy man is not able to visualize them, or perhaps the cost of making the change seems to outweigh the intangible benefits that are expected. If a suggestion of this type is rejected after proper presentation, the suggester should drop it and cease to worry about it. Fretting about unadopted ideas occupies the mind when it should be engaged in originating new suggestions and often causes dissatisfaction and reduces efficiency.

The rejection of an idea does not mean that it possesses no merit. It merely indicates that the benefits it offered did not appear to the one who made the decision to be sufficiently important to warrant expending the effort necessary to get them. The decision is made in the light of such factors as present trends, the future business outlook, and the amount of money available for making improvements. In 6 months or a year, the situation may have changed, and the idea may be welcomed and adopted upon re-presentation. If the idea is presented the second time by another individual, the one who first presented it has a natural tendency to feel discouraged. He must ward off this feeling by recognizing that conditions change and that fresh angles of presentation often lead to the adoption of old ideas. The best antidote against discouragement is to go out and discover another idea. Solving problems and originating suggestions bring satisfaction to the type of men who are in supervisory positions and help to make the daily job more interesting.

(Source:  Chapter 2 - Operation Analysis by Maynard)


Updated 22 August 2017, 23 November 2013

Factory - Early Origin - History

In a factory  workers were concentrated under one roof, and subjected to discipline and supervision.


Pollard (1968) in his classic work on the rise of Factory, mentions three large plants, all employing over 500 employees before 1750.  Perhaps the most “modern” of all industries was silk throwing. The silk mills in Derby built by Thomas Lombe in 1718 employed 300 workers and was located in a five-story building. After Lombe’s patent expired, large mills patterned after his were built in other places as well. Equally famous was the Crowley ironworks, established in 1682 in Stourbridge in the midlands (not far from Birmingham) and which employed at its peak 800 employees.

Richard Arkwright’s works in Cromford employed about 300 workers; he also helped found the New Lanark mills in Scotland which employed a workforce of 1600 in 1815 (most of which were indoor). Such huge firms were unusual, perhaps, but by 1800, there were in Britain around 900 cotton-spinning factories, of which a third were “mills” employing over 50 workers and the rest small sheds and workshops, with a handful of workers – though even those by that time were larger than households.


Cyfarthfa ironworks in Wales which employed 1500 men in 1810 and 5,000 in 1830.


The first factory in the United States was begun after George Washington became President. In 1790, SAMUEL SLATER, a cotton spinner's apprentice who left England the year before with the secrets of textile machinery, built a factory from memory to produce spindles of yarn.

The factory had 72 spindles, powered by by nine children pushing foot treadles, soon replaced by water power. Three years later, JOHN AND ARTHUR SHOFIELD, who also came from England, built the first factory to manufacture woolens in Massachusetts.

From these humble beginnings to the time of the Civil War there were over two million spindles in over 1200 cotton factories and 1500 woolen factories in the United States.


http://time.dufe.edu.cn/jingjiwencong/waiwenziliao/pittsburgh.pdf

http://www.ushistory.org/us/25d.asp

Scope and Limitations of Methods Efficiency Engineering



Wide Scope of Methods Efficiency Engineering


Methods efficiency engineering principles have been applied to a wide variety of work. But still there are men who wish to know what value methods efficiency engineering steps have for their particular processes. Therefore, it will be useful to outline the scope of methods efficiency engineering and to define the limits of its application.

Many executives feel "Our Work Is Different."  They agree that  methods efficiency engineering  has unquestionably accomplished worth-while results in certain lines of work or in certain industries. But still they feel , it has no value in their particular line of work.

 If it happens to be of a jobbing or small-quantity nature, it is felt that the field of operation analysis is limited to mass production. A foundry feels that the technique is more applicable to a machine shop, and the machine shop feels that it is useful chiefly in assembly work.

Wherever the Methods efficiency engineering technique has been properly applied by a competent engineer, beneficial, almost spectacular, results have been obtained. This, if it were generally known, should do much to offset the feeling described above. The principles of methods efficiency engineering are fundamental, and they can be applied to any class of work. It makes no difference if a plant is manufacturing toys, tools, trains, or tractors ; the principles apply equally to all.

The reason for this is that all work may be resolved into terms that are more or less basic. During operation analysis, one of the points that are considered is the purpose of the operation. It is just as useful to consider the purpose of grinding a part that goes inside a large steam turbine as it is to consider the purpose of the bending of a part that fits in an agricultural machine. It is as important to analyze the inspection requirements of a toy shovel as it is to analyze those of a gear bushing. The inspection requirements partly determine "the operations that must be performed in. either case and hence should be gone into carefully. Material handling presents problems that must be solved whether the product handled is bread, tooth paste, shoes, or patent medicine.

Working methods present points of remarkable similarity when closely analyzed.

The motion made by a mechanic in reaching for a screw driver is the same as that used by a sewing-machine operator in reaching for a pair of scissors or by a fitter in reaching for 'a piece of material or by a molder in reaching for his rammer or, for that matter, by a dentist reaching for his chisel. If one can be shortened and made less fatiguing, the others can also be made less fatiguing..

The same logic equally to large parts. The problems involved in lifting a ladle of molten metal with a crane are the same regardless of whether the metal happens to be copper, iron, or steel. Castings and forgings both present handling problems that are related. Countless similar examples can be taken from all types of industry.

Hence, it may be seen that the application of the principles of operation analysis is not limited by the nature of the product. In view of the prevalence of the " our-work-is-different " attitude, this point cannot be too highly stressed.

Effect of Quantity on Field of Operation Analysis

If a large number of man-hours are expended upon a certain line of work, a 1 per cent saving may be important, whereas a 10 per cent saving on inactive work might not offset the cost of making the
study. Hence, it is almost axiomatic that it is more profitable to study the work with the greatest activity. This does not mean, however, that only mass-production work can be studied. There is need for cost reduction in jobbing production also and jobbing processes can also improved using methods efficiency engineering.

An operation may be repetitive from the viewpoint of the methods engineer in so far as analysis is concerned even though the quantities in which individual parts are made are quite small. This viewpoint is different from that which considers a job repetitive only when a large number of duplicate parts are produced.

For purposes of analysis, the methods engineer looks at an operation not as a single quantity but rather as a series of elemental operations. Therefore, when a number of different but similar jobs are reduced to their elements, it is found that several of the elements are common to all jobs. If an element is shortened on one job, it may be shortened on all jobs in which it occurs, and thus a saving is obtained over the entire line of work that may be of great magnitude.

Jobs that are molded on the bench in a foundry are not considered as being repetitive. Any one casting that was ordered in quantities would be made on a molding machine, However, if several bench molders work continuously at making molds, the operation will be considered as repetitive by the methods engineer.

The first operation performed by a bench molder in beginning to put up a mold is "place match or molding board on bench. If a standard flask is used and 10 molders put up 20 molds per day on the average, the operation will be performed 200 times per day or 60,000 times a year. Hence, it may be seen that under these conditions, the element  "place match or molding board on bench"  is truly a repetitive operation. It will be worth while to, study the location of the molding boards and the motions used for handling them. If by careful analysis of the type described for laying out the bookkeeper's desk the time required to place the match or molding board is reduced from 0.0030 to 0.0015 hour, 0.0015 X 60,000 or 90 hours per year will be saved. This at an average bench molder's rate will amount to a worth-while total.

Similarly such elements as " place drag " apply parting sand, "fill riddle,' and so on, are repetitive elements. They occur on every mold made and are not affected by the nature of the patterns In the mold. Hence, it will be profitable to consider each of these elements in detail, for any improvement made will apply to the entire bench-molding activity.

Certain elements vary with every job. Therefore, they are not repetitive in the sense that the element "place match or molding board on bench'  is repetitive. The variation is in degree rather than in kind,, however, and hence even the variable elements have repetitive characteristics. When a mold must be reinforced with nails, the time for the element "reinforce mold " will vary with the number of nails placed. However, the same motions are used whenever a nail is placed, and hence an improvement in the method of securing and placing a nail will amount to a sizable saving in the bench-molding work as a whole.

This same principle applies to all lines of work. Machine work even in the jobbing shop is repetitive if the machines work steadily. Most machine work may be reduced to less than 100 elements which are repeated over and over again.

Therefore, it will be seen that operation analysis is not limited to large-quantity work but may be applied to advantage to any line of work on which a fair number of man-hours are expended. Usually, if a line of work has not been studied with the modern analysis approach, it is profitable to study it if one or more men
are engaged full time upon it.

Class of Work to Which Operation Analysis Is Not Applicable

If job-analysis methods may be applied to any product and to all lines of work requiring the full-time services of one or more men, it follows that the only work to which it is not applicable is that which occupies only part of the time of one individual. A general machine shop may possess a broaching machine to take care of special jobs. If jobs requiring broaching are so infrequent that the machine operates only two days a month, detailed study of the operation will not be economically justified.

Source: Operation Analysis by Maynard

Full Knol Book - Method Study: Methods Efficiency Engineering - Knol Book


Tools and Combination Tools Electronics Assembly



Since the early days of the electronics industry Lindstrom has been the Brand manufacturers chose for high volume work and critical applications. Our RX Series ergonomic cutters were the first designed to fit the tool to the user, and revolutionized the handtool industry, beginning in electronics assembly and aerospace production.

As these industries matured devices shrank in size and increased in complexity and Lindstrom developed new profiles on pliers and cutter types to meet their demands: Ultra-Flush cutters for anti-shock military applications, tapered and relieved cutters to get in between and under tiny components, super-radiused pliers to bend sensitive wire without scratching, and extra-small tip cutters for microscopy. Still, the most valued feature of Lindstrom tools is high quality, from the famous Swedish steel to the attention to detail.

TL 29D tweezers: reverse action gently holds component (special pliers shown).

RX8248 Flush cutters: 45° angled tips, long 18 mm jaws for improved access.

TL 51S-SA-ET tweezers: soft ESD-safe, cleanroom compatible Ergo-Touch grips.
http://www.lindstromtools.us/products/electronics-assembly

http://www.tdiinternational.com/contents/en-us/d861_tdi-precision-handtools.html

Precision Hand Tools used in Electronics Assembly
Typical Applications for TDI Hand Tools:

Electronics, Medical Device, Laser, Microwave and Disk Drive Assembly
Electronic PCB Assembly
Circuit Die and Integrated Circuit Package Assembly
Circuit Board Repair and Rework
Biotech, Biology, Military and Aerospace Electronics Assembly
Surface Mount Rework and Assembly
Labs, R&D, Cleanrooms and ESD Sensitive Applications
Work under a Microscope / Microelectronics
Handling of Small Components, Wafers, Substrates and Wires
Wire and Lead Cutting
Wafer Pick and Place
Holding Parts for Soldering
Precision Electronics Assembly Handtools

Printed Circuit Board / Package

TDI offers the largest selection of ESD Safe static dissipative handtools for critical ESD low voltage applications.



Precision Tweezers for Electronics Assembly & Labs    
TWEEZERS

Offering the highest precision Swiss tweezers for electronics and medical device assembly, laboratories and application specific applications. TDI's Swiss tweezer provide high precision tip symmetry and balance, with polished tip edges and non-scratch anti-glare finish. Lead free.

Metal Tweezers - Swiss Super Alloy, Swiss stainless anti-magnetic, Italian stainless anti-magnetic and industrial grade metal tweezers.

General Purpose Stainless Anti-Magnetic Tweezers

Fiber Tip Tweezers

Cushion Grip Tweezers - ESD Safe

ESD Safe Static Dissipative Tweezers - For the most critical ESD applications (<50V ESD Threshold)

Application Specific Tweezers - Component, flat tip, reverse action, surface mount, tweezer cutters & wafer handling.





VACUUM PICKUP TOOLS

Constant Vacuum Pickup Tools - For In-Line Vacuum Source
For use with in-line vacuum systems. Purchase individual handles, tips & hoses. Ergonomic light weight handles - precision vacuum handling of small parts.

Complete Constant Vacuum Pickup Kits - With Vacuum Pumps
Complete kits include vacuum pumps, handles, hoses and tips.

Portable Vacuum Pickup Wands
Self contained, portable vacuum pickup tools. No batteries or hoses required.

Individual Vacuum Pickup Tool Parts
Vacuum cups, probes, filters for vacuum pickup wand handle, static dissipative vacuum hose, hose adapters and fittings.

WaferPik® Portable
Portable vacuum wafer pickup tool. Piston activated vacuum, no batteries required. Holds 3-12" wafers and fits between 3/16" wafer spacing.

Vacuum Pickup Tools for electronics assembly and labs.

 

Precision Lead Cutters, Pliers and Micro Shears for Electronics Assembly  
WIRE CUTTERS, PLIERS AND SHEARS



Oval Wire Cutters - ESD Safe Cushion Grips

Taper Wire Cutters - ESD Safe Cushion Grips

Angulated Wire Cutters - ESD Safe Cushion Grips

Tip Cutters - ESD Safe Cushion Grips

Pliers - ESD Safe Cushion Grips

Micro Shears - ESD Safe Non-Slip Grips

 

MICRO MINI TOOLS



Diamond Scribes

Micro Probes

Micro Rulers - For use under microscopes.

Micro Pliers - Reverse action, squeeze to open.

Micro Scissors

Micro Spatulas (Oilers) ESD Safe Versions now Available

Pin Vise Tool Handles

Micro Mini Tools, Rulers, Diamond Scribes & Scissors



Precision wire-cutting scissors for electronics assembly.  
SCISSORS



Stainless Steel Scissors

Micro Scissors - Reverse action, squeeze to open.

Ceramic Tip Scissors - Static Dissipative JD Ceramic Tips. Stainless Handles.



INSPECTION / REWORK / OTHER TOOLS

Probes - Stainless steel, conductive PEEK and also with ESD safe / ergonomic cushion grips.

Spatulas - Stainless steel spatulas and micro spatulas (oilers).

Scalpels (Non Surgical) - #1 and #3 handles and interchangeable blades.  Also with ESD safe / ergonomic cushion grips.

Inspection Mirrors - Adjustable stainless steel mirrors.

Component Grabber - 4-prong small parts/component grabber.

Pin Vise Handles - Stainless steel pin vise handles, also with ESD safe / ergonomic cushion grips.

Micro Pliers Stainless steel, reverse action squeeze to open.

Inspecition and circuit board rework handtools



Printed Circuit Board Holders    
PRINTED CIRCUIT BOARD HOLDERS

These circuit board holders are the perfect support for assembly and soldering/desoldering processes of printed circuit boards. The holder can be easily taken apart into single pieces and reassembled in different combinations. Complete with cover protected by ESD safe foam and dividers.

PCB - Printed Circuit Board


TDI LCR SMART TWEEZERS



Inductance (L), capacitance (C) and resistance (R) can be measured with automatic selection of the test parameters and test range.
Convenient one hand operation, can easily be set for right or left hand use via the navigation menu.
Ideal for Surface Mount Devices
Automated Component Identification
Precise Test Leads made in Switzerland.
Portable and Ergonomic Design.
Comes with built in Li-Ion rechargeable battery. Battery replacements are not required.
Universal 110-220V power supply, micro USB charging cord and hard carrying case are included.

http://www.tdiinternational.com/contents/en-us/d861_tdi-precision-handtools.html

Friday, November 22, 2013

Radar Value Engineering


Customer Problem:

A surveillance radar with outdated, proprietary computer hardware and software had limited performance and limited technical refresh capability, with much higher, long term maintenance costs. Use of proprietary systems had also led to decreased reliability, maintainability, and availability, rendering the radar ineffective, and/or inoperable at critical times, resulting in valuable data losses during execution of costly flight and ground test activities.

What INTUITIVE did:

The Value Engineering (VE) Team used the VE methodology to mitigate obsolescence of the signal data processing equipment utilized by the sensors. Efforts identified decommissioned government furnished equipment, which were inexpensively purchased from an alternate government agency and applied toward future builds of radars.

Impact:

The VE Program avoided major and costly redesign and accelerated the production and fielding of new radar units, as well as improved the availability of cost-effective radar components and assemblies resulting in a saving of over $116M.
http://www.irtc-hq.com/projects/value-engineering/


Value Engineering
Theater High Altitude Area Defense (THAAD)
Transmit / Receive Module

Photo of Theater High Altitude Area Defense (THAAD) - Transmit/Receive Integrated Multi-channel Module (T/RIMM) Part of the transmit/receive module of the THAAD radar was a Transmit/Receive Element Assembly (T/REA) type architecture. This technology is costly and outdated. A study was conducted to determine possible alternatives for improved performance and cost reduction of the module. The study determined that the transmit/receive function of the radar could be accomplished at a lower cost through a Transmit/Receive Integrated Multi-channel Module (T/RIMM) architecture developed by Raytheon Electronic Systems.

The T/REA type architecture was replaced with the T/RIMM type architecture on the radar module, greatly reducing the life cycle cost of the THAAD radar.
 
The Government Saved $27.4M Over a 7 - Year Period in Cost Avoidance.
http://www.redstone.army.mil/amrdec/io/VEP_EX2.html

Monday, November 18, 2013

Muda, Muri, Mura - Industrial Engineering and Buddhism Relation - Japan


In Japan, Total Industrial Engineering is defined as eliminating Muda, Muri and Mura.

Without Reason (Muri), Inconsistent (Mura) and a Man Without a Horse (Muda).

There are used even in martial arts training
http://www.budotheory.ca/index.php/budo-theory-book/28-resources/resarticles/59-without-reason-inconsistent-wasteful-muri-mura-muda

The terms are connected to Buddhist philosophy.

Muri is inadequate resources and Muda is waste of resources. When you do a thing without both of them you are doing moderation, the Buddhist philosophy.


Sunday, November 17, 2013

Summary - Principles of Jig and Fixture Design

Summary of Principles of Jig Design. Summarizing  the following rules may be given as the main
points to be considered in the designing of jigs and fixtures:

1. Before planning the design of a tool, compare the cost of production of the work with present tools with the expected cost of production, using the tool to be made, and see that the cost of building is not in excess of expected gain.

2. Before laying out the jig or fixture, decide upon the locating points and outline a clamping arrangement.

3. Make all clamping and binding devices as quick-acting as possible.

4. In selecting locating points, see that two component parts of a machine can be located from corresponding points and surfaces.

5. Make the jig " fool-proof "; that is, arrange it so that the work cannot be inserted except in the correct way.

6. For rough castings, make some of the locating points adjustable.

7. Locate clamps so that they will be in the best position to resist the pressure of the cutting tool when at work.

8. Make, if possible, all clamps integral parts of the jig or fixture.

9. Avoid complicated clamping arrangements, which are liable to wear or get out of order.

10. Place all clamps as nearly as possible opposite some bearing point of the work, to avoid springing.

11. Core out all unnecessary metal, making the tools as light as possible, consistent with rigidity and stiffness.

12. Round all corners.

13. Provide handles wherever these will make the handling of the jig more convenient.

14. Provide feet, preferably four, opposite all surfaces containing guide bushings in drilling and boring jigs.

15. Place all bushings inside of the geometrical figure formed by connecting the points of location of the feet.

1 6. Provide abundant clearance, particularly for rough castings.

17. Make, if possible, all locating points visible to the operator when placing the work in position.

18. Provide holes or escapes for the chips.

19. Provide clamping lugs, located so as to prevent springing of the fixture, on all tools which must be held to the table of the machine while in use, and tongues for the slots in the tables in all milling and planing fixtures.

20. Before using in the shop, for commercial purposes, test all jigs as soon as made.

Detailed Explanation of Principles 

Jig and Fixture Design - Principles


PRINCIPLES OF JIG DESIGN

Jigs and fixtures may be defined as devices used in the manufacture of duplicate parts of machines and intended to make possible interchangeable work at a reduced cost, as compared
with the cost of producing each machine detail individually.
Jigs and fixtures serve the purpose of holding and properly locat- ing a piece of work while machined, and are provided with neces- sary, appliances for guiding, supporting, setting, and gaging the tools in such a manner that all the work produced in the same jig or fixture will be alike in all respects, even with the employ- ment of unskilled labor. When using the expression "alike," it implies, of course, simply that the pieces will be near enough alike for the purposes for which the work being machined is intended. Thus, for certain classes of work, wider limits of variation will be permissible without affecting the proper use
of the piece machined, while in other cases the limits of varia- tion will be so small as to make the expression "perfectly alike" literally true.

Objects of Jigs and Fixtures. The main object of using jigs and fixtures is the reduction of the cost of machines or machine details made in great numbers. This reduction of cost is ob- tained in consequence of the increased rapidity with which the
machines may be built and the employment of cheaper labor,
which is possible when using tools for interchangeable manu-
facturing. Another object, not less important, is the accuracy
with which the work can be produced, making it possible to
assemble the pieces produced in jigs without any great amount of
fitting in the assembling department, thus also effecting a great
saving in this respect. The use of jigs and fixtures practically
does away with the fitting, as this expression was understood in
the old-time shop; it eliminates cut-and-try methods, and does
away with so-called "patch- work" in the production of machin-
ery. It makes it possible to have all the machines built in the
shop according to the drawings, a thing which is rather difficult
to do if each individual machine in a large lot is built without
reference to the other machines in the same lot.

The interchangeability obtained by the use of jigs and fixtures
makes it also an easy matter to quickly replace broken or worn-
out parts without great additional cost and trouble. When
machines are built on the individual plan, it is necessary to fit
the part replacing the broken or worn-out piece, in place, involv-
ing considerable extra expense, not to mention the delay and the
difficulties occasioned thereby.

As mentioned, jigs and fixtures permit the employment of
practically unskilled labor. There are many operations in the
building of a machine, which, if each machine were built indi-
vidually, without the use of special tools, would require the work
of expert machinists and toolmakers. Special tools, in the form
of jigs and fixtures, permit equally good, or, in some cases, even
better results to be obtained by a much cheaper class of labor,
provided the jigs and fixtures are properly designed and cor-
rectly made. Another possibility for saving, particularly in the
case of drill and boring jigs provided with guide bushings in the
same plane, is met with in the fact that such jigs are adapted to
be used in multiple-spindle drills, thereby still more increasing
the rapidity with which the work may be produced. In shops
where a great many duplicate parts are made, containing a
number of drilled holes, multiple-spindle drills of complicated
design, which may be rather expensive as regards first cost, are
really cheaper, by far, than ordinary simple drill presses.

Another advantage which has been gained by the use of jigs and fixtures, and which should not be lost sight of in the enu- meration of the points in favor of building machinery by the use
of special tools, is that the details of a machine that has been
provided with a complete equipment of accurate and durable
jigs and fixtures can all be finished simultaneously in different
departments of a large factory, without inconvenience, thus mak-
ing it possible to assemble the machine at once after receiving
the parts from the different departments; and there is no need
of waiting for the completion of one part into which another is
required to fit, before making this latter part. This gain in
time means a great deal in manufacturing, and was entirely
impossible under the old-time system of machine building, when
each part had to be made in the order in which it went to
the finished machine, and each consecutive part had to be lined
up with each one of the previously made and assembled details.
Brackets, bearings, etc., had to be drilled in place, often with
ratchet drills, which is a slow and always inconvenient operation.

Difference between Jigs and Fixtures. To exactly define the word "jig, " as considered apart from the word "fixture,"
is difficult, as the difference between a jig and a fixture is often-
times not very easy to decide. The word jig is frequently, al-
though incorrectly, applied to any kind of a work-holding appli-
ance used in the building of machinery, the same as, in some
shops, the word fixture is applied to all kinds of special tools.
As a general rule, however, a jig is a special tool, which, while it
holds the work, or is held onto the work, also contains guides
for the respective tools to be used; whereas a fixture is only
holding the work while the cutting tools are performing the oper-
ation on the piece, without containing any special arrangements
for guiding these tools. The fixture, therefore, must, itself, be
securely held or fixed to the machine on which the operation is
performed; hence the name. A fixture, however, may sometimes
be provided with a number of gages and stops, although it does
not contain any special devices for the guiding of the tools.

The definition given, in a general way, would therefore clas- sify jigs as special tools used particularly in drilling and boring
operations, while fixtures, in particular, would be those special
tools used on milling machines, and, in some cases, on planers,
shapers, and slotting machines. Special tools used on the lathe
may be either of the nature of jigs or fixtures, and sometimes the
special tool is actually a combination of both, in which case the
term drilling fixture, boring fixture, etc., is suitable.

Fundamental Principles of Jig Design. Before entering upon a discussion of the minor details of the design of jigs and fixtures, the fundamental principles of jig and fixture design will be briefly outlined. Whenever a jig is made for a compo- nent part of a machine, it is almost always required that a corre- sponding jig be made up for the place on the machine, or other part, where the first-mentioned detail is to be attached. It is,
of course, absolutely necessary that these two jigs be perfectly alike as to the location of guides and gage points. In order 'to
have the holes and guides in the two jigs in alignment, it is advis-
able, and almost always cheaper and quicker, to transfer the
holes or the gage points from the first jig made to the other. In
many instances, it is possible to use the same jig for both parts.
Cases where the one or the other of these principles is applicable
will be shown in the following chapters in the detailed descrip-
tions of drill and boring jigs.

There are some cases where it is not advisable to make two jigs, one for each of the two parts which are to fit together. It
may be impossible to properly locate the jig on one of the parts
to be drilled, or, if the jig were made, it may be so complicated
that it would not be economical. Under such conditions the
component part itself may be used as a jig, and the respective
holes in this part used as guides for the tools when machining
the machine details into which it fits. Guide bushings for the
drills and boring bars may then be placed in the holes in the
component part itself. In many cases, drilling and boring opera-
tions are also done, to great advantage, by using the brackets
and bearings already assembled and fastened to the machine
body as guides.

One of the most important questions to be decided before mak- ing a jig is the amount of money which can be expended on a
special tool for the operation required. In many cases, it is
possible to get a highly efficient tool by making it more compli-
cated and more expensive, whereas a less efficient tool may be
produced at very small expense. To decide which of these two
types of jigs and fixtures should be designed in each individual
case depends entirely upon the circumstances. There should be
a careful comparison of the present cost of carrying out a certain
operation, the expected cost of carrying out the same operation
with an efficient tool, and the cost of building that tool itself.
Unless this is done, it is likely that the shop is burdened with a
great number of special tools and fixtures which, while they
may be very useful for the production of the parts for which they
are intended, actually involve a loss. It is readily seen how
uneconomical it would be to make an expensive jig and fixture
for a machine or a part of a machine that would only have to
be duplicated a few times. In some cases, of course, there may
be a gain in using special devices in order to get extremely good
and accurate results.

Locating Points. The most important requirements in the design of jigs are that good facilities be provided for locating the
work, and that the piece to be machined may be easily inserted
and quickly taken out of the jig, so that no time is wasted in
placing the work in position on the machine performing the work.
In some cases, a longer time is required for locating and clamp-
ing the piece to be worked upon than is required for the actual
machine operation itself. In all such cases the machine per-
forming the work is actually idle the greater part of the time, and,
added to the loss of the operator's time, is the increased expense
for machine cost incurred by such a condition. For this reason,
the locating and clamping of the work in place quickly and
accurately should be carefully studied by the designer before
any attempt is made to design the tool. In choosing the locat-
ing surface or points of the piece or part, consideration must be
given to the facilities for locating the corresponding part of the
machine in a similar manner. It is highly important that this
be done, as otherwise, although the jigs may be alike, as far as
their guiding appliances are concerned, there may be no facility
for locating the corresponding part in the same manner as the
one already drilled, and while the holes drilled may coincide,
other surfaces, also required to coincide, may be considerably
out of line. One of the main principles of location, therefore,
is that two component parts of the machine should be located
from corresponding points and surfaces.

If possible, special arrangements should be made in the design of the jig so that it is impossible to insert the piece in any but the correct way. Mistakes are often made on this account
in shops where a great deal of cheap help is used, pieces being
placed in jigs upside down, or in some way other than the cor-
rect one, and work that has been previously machined at the
expenditure of a great deal of time is entirely spoiled. There-
fore, whenever possible, a jig should be made " fool-proof ."

When the work to be machined varies in shape and size, as,
for instance, in the case of rough castings, it is necessary to have
at least some of the locating points adjustable and placed so
that they can be easily reached for adjustment, but, at the same
time, so fastened that they are, to a certain extent, positive. In
the following chapters different kinds of adjustable locating
points will be described in detail.

Clamping Devices. The strapping or clamping arrangements should be as simple as possible, without sacrificing effectiveness, and the strength of the clamps should be such as to not only hold
the piece firmly in place, but also to take the strain of the cutting
tools without springing or " giving." When designing the jig,
the direction in which the strain of the tool or cutters acts upon
the work should always be considered, and the clamps so placed
that they will have the highest degree of strength to resist the
pressure of the cut.

The main principles in the application of clamps to a jig or fixture are tha they should be convenient for the operator, quickly operated, and, when detached from the work, still con-
nected with the jig or fixture itself, so as to prevent the oper-
ator from losing them. Many a time, looking for lost straps,
clamps, screws, etc., causes more delay in shops than the extra
cost incurred in designing a jig or fixture somewhat more com-
plicated, in order to make the binding arrangement an integral
part of the fixture itself. Great complication in the clamping
arrangements, however, is not advisable. Usually clamping
arrangements of this kind work well when the fixture is new, but,
as the various parts become worn, complicated arrangements
are more likely to get out of order, and the extra cost incurred in
repairing often outweighs the temporary gain in quickness of
operation.


The judgment of the designer is, in every case, the most im-
portant point in the design of jigs and fixtures. Definite rules
for all cases cannot be given. General principles can be studied,
but the efficiency of the individual tool will depend entirely upon
the judgment of the tool designer in applying the general prin-
ciples of tool design to the case in hand.

When designing the jig or fixture, the locating and bearing points for the work and the location of the clamps must also be
so selected that there is as little liability as possible of springing
the piece or jig, or both, out of shape, when applying the clamps.
The springing of either the one or the other part will cause in-
correct results, as the work surfaces will be out of alignment with
the holes drilled or the faces milled. The clamps or straps
should therefore, as far as possible, be so placed that they are
exactly opposite some bearing point or surface on the work.

Weight of Jigs. The designer must use his judgment in re- gard to the amount of metal put into the jig or fixture. It is
desirable to make these tools as light as possible, in order that
they may be easily handled, be of smaller size, and cost less in
regard to the amount of material used for their making, but, at
the same time, it is poor economy to sacrifice any of the rigidity
and stiffness of the tool, as this is one of the main considerations
in obtaining efficient results. On large-sized jigs and fixtures,
it is possible to core out the metal in a number of places, without
decreasing, in the least, the strength of the jig itself. The
corners of jigs and fixtures should always be well rounded, and
all burrs and sharp edges filed off, so as to make them convenient
and pleasant for handling. Smaller jigs should also be made
with handles in proper places, so that they may be held in posi-
tion while working, as in the case of drilling jigs, and also for
convenience in moving the jig about.

Jigs Provided with Feet. Ordinary drill jigs should always be provided with feet or legs on all sides which are opposite the holes for the bushings, so that the jig can be placed level on the
table of the machine. These feet also greatly facilitate the
making of the jig, making it easier to lay out and plane the differ-
ent finished surfaces. On the sides of the jig where no feet are
required, if the body is made from a casting, it is of advantage
to have small projecting lugs for bearing surfaces when laying
out and planing. While jigs are most commonly provided with
four feet on each side, in some cases it is sufficient to provide the
tool with only three feet, but care should be taken in either case
that all bushings and places where pressure will be applied to the
tool are placed inside of the geometrical figure obtained by con-
necting, by lines, the points of location for the feet.

While it may seem that three feet are preferable to use, because the jig will then always obtain a bearing on all the three feet,
which it would not with four feet, if the table of the machine
were not absolutely plane, it is not quite safe to use the smaller
number of supports, because a chip or some other object is liable
to come under one foot and throw the jig and the piece out of
line, without this being noticed by the operator. If the same
thing happens to a jig with four feet, it will rock and invariably
cause the operator to notice the defect. If the table is out of
true, this defect, too, will be noticed for the same reason.

Jig feet are generally cast solid with the jig frame. When the jig frame is made from machine steel, and sometimes in the case of cast-iron jigs, detachable feet are used.

Materials for Jigs. Opinions differ as to the relative merits of cast iron and steel as materials from which to construct the jig and fixture bodies. The decision on this point should depend
to a great extent upon the usage to which the fixture is to be put
and the character of the work which it is to handle. For small
and medium sized work, such as typewriter, sewing machine,
gun, adding machine, cash register, phonograph, and similar
parts, the steel jig offers decided advantages, but for larger work,
such as that encountered in automobile, engine, and machine tool
fixtures, the cast-iron jig is undoubtedly the cheaper and more
advisable to use. The steel jig should be left soft in order that
at any future time additional holes may be added, or the existing
bushings changed as required. With a cast-iron jig this adding
of bushings is a difficult matter, as the frame is usually bossed
and "spot finished" at the point where the bushings are located,
and it is very difficult to build up on the jig frame in order to
locate or change the bushings. When designing the jig, these
points should be remembered and provision made for them,
where possible.

General Remarks on Jig Design. One mistake, quite frequently made, is that of giving too little clearance between the piece to be machined and the walls or sides of the jig used for it.
Plenty of clearance should always be allowed, particularly when
rough castings are being drilled or machined in the jigs; besides,
those surfaces in the jig which do not actually bear upon the
work do not always come exactly to the dimensions indicated on
the drawing, particularly in a cast-iron jig, and allowance ought
to be made for such differences.

In regard to the locating points, it ought to be remarked that, in all instances, these should be visible to the operator when placing the work in position, so that he may be enabled to see
that the work really is in its right place. At times the construc-
tion of the piece to be worked upon may prevent a full view of
the locating points. In such a case a cored or drilled hole in the
jig, near the locating seat, will enable a view of same, so that the
operator may either see that the work rests upon the locating
point, or so that he can place a feeler or thickness gage between
the work and the locating surface, to make sure that he has the
work in its correct position. Another point that should not be
overlooked is that jigs and fixtures should be designed with a view
of making them easily cleaned from the chips, and provision
should also be made so that the chips, as far as possible, may fall
out of the jig and not accumulate on or about the locating points,
where they are liable to throw the work out of its correct position
and consequently spoil the piece.

The principles so far referred to have all been in relation to the holding of the work in the jig, and the general design of the jig for producing accurate work. Provisions, however, should
also be made for clamping the jig or fixture to the table of the
machine, in cases where it is necessary to have the tool fixed
while in operation. Small drilling jigs are not clamped to the
table, but boring jigs and milling and planing fixtures invariably
must be firmly secured to the machine on which they are used.
Plain lugs, projecting out in the same plane as the bottom of
the jig, or lugs with a slot in them to fit the body of T-bolts, are
the common means for clamping fixtures to the table. For
boring jigs, it is unnecessary to provide more than three such
clamping points, as a greater number is likely to cause some
springing action in the fixture. A slight springing effect is almost
unavoidable, no matter how strong and heavy the jig is, but, by
properly applying the clamps, it is possible to confine this spring-
ing within commercial limits.

Jigs should always be tested before they are used, so as to make sure that the guiding provisions are placed in the right relation to the locating points and in proper relation to each other.

Summary of Principles of Jig Design. Summarizing the principles referred to, the following rules may be given as the main
points to be considered in the designing of jigs and fixtures:

1. Before planning the design of a tool, compare the cost of production of the work with present tools with the expected cost of production, using the tool to be made, and see that the cost of building is not in excess of expected gain.

2. Before laying out the jig or fixture, decide upon the locating points and outline a clamping arrangement.

3. Make all clamping and binding devices as quick-acting as possible.

4. In selecting locating points, see that two component parts of a machine can be located from corresponding points and surfaces.

5. Make the jig " fool-proof "; that is, arrange it so that the work cannot be inserted except in the correct way.

6. For rough castings, make some of the locating points adjustable.

7. Locate clamps so that they will be in the best position to resist the pressure of the cutting tool when at work.

8. Make, if possible, all clamps integral parts of the jig or fixture.

9. Avoid complicated clamping arrangements, which are liable to wear or get out of order.

10. Place all clamps as nearly as possible opposite some bearing point of the work, to avoid springing.

11. Core out all unnecessary metal, making the tools as light as possible, consistent with rigidity and stiffness.

12. Round all corners.

13. Provide handles wherever these will make the handling of the jig more convenient.

14. Provide feet, preferably four, opposite all surfaces containing guide bushings in drilling and boring jigs.

15. Place all bushings inside of the geometrical figure formed by connecting the points of location of the feet.

1 6. Provide abundant clearance, particularly for rough castings.

17. Make, if possible, all locating points visible to the operator when placing the work in position.

18. Provide holes or escapes for the chips.

19. Provide clamping lugs, located so as to prevent springing of the fixture, on all tools which must be held to the table of the machine while in use, and tongues for the slots in the tables in all milling and planing fixtures.

20. Before using in the shop, for commercial purposes, test all jigs as soon as made.

Types of Jigs. The two principal classes of jigs are drill jigs and boring jigs. Fixtures may be grouped as milling, planing, and splining fixtures, although there are a number of special fixtures which could not be classified under any special head.

Drill jigs are intended exclusively for drilling, reaming, tap-
ping, and facing. Whenever these four operations are required
on a piece of work, it is, as a rule, possible to provide the neces-
sary arrangements for performing all these operations in one
and the same jig. Sometimes separate jigs are made for each
one of these operations, but it is doubtless more convenient
and cheaper to have one jig do for all, as the design of the jig
will not be much more complicated. Although it may be pos-
sible to make a distinction between a number of different types
of drill jigs, it is almost impossible to define and to get proper
names for the various classes, owing to the great variety of
shapes of the work to be drilled. There are, however, two general
types that are most commonly used, the difference between
them being very marked. These types may be classified as
open jigs and closed jigs, or box jigs. Sometimes the open jigs
are called clamping jigs. The open jigs usually have all the drill
bushings in the same plane, parallel with one another, and are
not provided with loose or removable walls or leaves, thereby
making it possible to insert the piece to be drilled without any
manipulation of the parts of the jig. These jigs are often of
such a construction that they are applied to the work to be
drilled, the jig being placed on the work, rather than the work
being placed in the jig. The jig may be held to the work by
straps, bolts, or clamps, but in many cases the jig fits into or
over some finished part of the work and in this way the jig is
located and held in position.

The closed drill jigs, or box jigs, frequently resemble some
form of a box and are intended for pieces where the holes are
to be drilled at various angles to one another. As a rule, the
piece to be drilled can be inserted in the jig only after one or
more leaves or covers have been swung out of the way. Some-
times it is necessary to remove a loose wall, which is held by
bolts and dowel pins, in order to locate the piece in the jig.
The work in the closed drill jig may be held in place by set-
screws, screw bushings, straps, or hook-bolts.

The combination drilling and boring jig is another type of
closed jig designed to serve both for drilling and boring opera-
tions. Before designing a combination drill and boring jig,
the relation between, and number of, the drilled and bored
holes must be taken into consideration, and also the size of the
piece to be machined. In case there is a great number of holes,
it may be of advantage to have two or even more jigs for the
same piece, because it makes it easier to design and make the
jig, and very likely will give a better result. The holes drilled
or bored in the first jig may be used as a means for locating the
piece in the jigs used later on. Combination drill and boring
jigs are not very well adapted for pieces of large size.

Open Jigs. Open jigs of the simpler forms are simply
plates provided with bushed holes which are located to cor-
respond with the required locations for the drilled holes. While
holes are sometimes drilled by first laying out the holes directly
upon the work, it is quite evident that this method of drilling
would not be efficient if a large number of duplicate parts had
to be drilled accurately, as there is likely to be more or less
variation in the location of the holes, and considerable loss of
time. In the first place, a certain amount of time is required
for laying out these holes preparatory to drilling. The operator,
when starting the drill, must also be careful to make it cut
concentric with the scribed circle, which requires extra time,
and there will necessarily be more or less variation. To over-
come these objections, jigs are almost universally used for hold-
ing the work and guiding the drill, when drilling duplicate parts,
especially when quite a large number of duplicate pieces must
be drilled.

The ring-shaped jig shown at A in Fig. i is used for drilling
the stud bolt holes in a cylinder flange and also for drilling the
cylinder head, which is bolted to the cylinder. The position of
the jig when the cylinder flange is being drilled is shown at
B. An annular projection on the jig fits closely in the cylinder
counterbore, as the illustration shows, to locate the jig concentric
with the bore. As the holes in the cylinder are to be tapped or
threaded for studs, a "tap drill," which is smaller in diameter
than the bolt body, is used and the drill is guided by a remov-
able bushing b of the proper size. Jigs of this type are often
held in position by inserting an accurately fitting plug through
the jig and into the first hole drilled, which prevents the jig
from turning with relation to the cylinder, when drilling the
other holes. When the jig is used for drilling the head, the
opposite side is placed
next to the work, as
shown at C. This side
has a circular recess or
counterbore, which fits
the projection on the
head to properly locate
the jig. As the holes in
the head must be slightly
larger in diameter than
the studs, another sized
drill and a guide bushing
of corresponding size are
used. The cylinder is, of
course, bored and the
head turned before the drilling is done.

Jigs of the open class, as well as those of other types, are
made in a great variety of shapes, and, when in use, they are
either applied to the work or the latter is placed in the jig.
When the work is quite large, the jig is frequently placed on it,
whereas small parts are more often held in the jig, which is so
designed that the work can be clamped in the proper position.
The form of any jig depends, to a great extent, on the shape of
the work for which it is intended and also on the location of
the holes to be drilled. As the number of differently shaped
pieces which go to make up even a single machine is often very
great, and as most parts require more or less drilling, jigs are
made in an almost endless variety of sizes and forms. When all
the holes to be drilled in a certain part are parallel, and es-
pecially if they are all in the same plane, a very simple form of
jig can ordinarily be used.

Box Jigs. A great many machine parts must be drilled on
different sides and frequently castings or forgings are very
irregular in shape, so that a jig which is made somewhat in
the form of a box, and encloses the work, is very essential, as
it enables the guide bushings to be placed on all sides and also
makes it comparatively easy to locate and securely clamp the
part in the proper position for drilling. This type of jig, which,
because of its form, is known as a closed or "box jig," is used
very extensively.

A box jig of simple design is shown in Fig. 2. This particu-
lar jig is used for drilling four small holes in a part (not shown)
which is located with reference to the guide bushings B by a
central pin A attached to the jig body. This pin enters a hole
in the work, which is finished in another machine in connection
with a previous operation. After the work is inserted in the
jig, it is clamped by closing the cover C, which is hinged at one
end and has a cam-shaped clamping latch D at the other, that
engages a pin E in the jig body. The four holes are drilled by
passing the drill through the guide bushings B in the cover.

Another jig of the same kind, but designed for drilling a
hole having two diameters through the center of a steel ball,
is shown in Fig. 3. The work, which is shown enlarged at A,
is inserted while the cover is thrown back as indicated by the
dotted lines. The cover is then closed and tightened by the
cam-latch Z), and the large part of the hole is drilled with
the jig in the position shown. The jig is then turned over and
a smaller drill of the correct size is fed through guide bushing
B on the opposite side. The depth of the large hole could be
gaged for each ball drilled, by feeding the drill spindle down to
a certain position as shown by graduation or other marks, but
if the spindle has an adjustable stop, this should be used. The
work is located in line with the two guide bushings by spherical
seats formed in the jig body and in the upper bushing, as shown.
As the work can be inserted and removed quickly, a large num-
ber of balls, which, practically speaking, are duplicates, can
be drilled in a comparatively short time by using a jig of this
type.

A box jig that differs somewhat in construction from the
design just referred to is illustrated at A in Fig. 4, which shows
a side and top view. The work, in this case, is a small casting
the form of which is indicated by the heavy dot-and-dash lines.
This casting is drilled at a, b, and c, and the two larger holes a
and b are finished by reaming. The hinged cover of this jig
is opened for inserting the work by unscrewing the T-shaped
clamping screw s one-quarter of a turn, which brings the head
in line with a slot in the cover. The casting is clamped by tighten-
ing this screw, which forces an adjustable screw bushing g down
against the work. By having this bushing adjustable, it can
be set to give the right pressure, and, if the height of the cast-
ings should vary, the position of the clamping bushing could
easily be changed.

The work is properly located by the inner ends of the three
guide bushings ai, bi, and ci, and also by the locating screws I
against which the casting is held by knurled thumb-screws m
and n. When the holes a and b are being drilled, the jig is
placed with the cover side down, as shown at A in Fig. 5, and
the drill is guided by removable bushings, one of which is shown
at r. When the drilling is completed, the drill bushings are
replaced by reamer bushings and each hole is finished by ream-
ing. The small hole c, Fig. 4, is drilled in the end of the cast-
ing by simply placing the jig on end as shown at B, Fig. 5.
Box jigs which have to be placed in more than one position
for drilling the different holes are usually provided with feet
or extensions, as shown, which are accurately finished to align
the guide bushings properly with the drill. These feet extend
beyond any clamping screws, bolts, or bushings which may
protrude from the sides of the jigs, and provide a solid support.
When inserting work in a jig, care should be taken to remove
all chips which might have fallen upon those surfaces against
which the work is clamped and which determine its location.

Still another jig of the box type, which is quite similar to
the one shown at A, Fig. 4, but is arranged differently, owing
to the shape of the work and location of the holes, is shown
at B in the same illustration. The work has three holes in
the base h, and a hole at i which is at an angle of 5 degrees
with the base. The three holes are drilled with the jig stand-
ing on the opposite end y, and the angular hole is drilled while
the jig rests on the four feet k, the ends of which are at such an
angle with the jig body that the guide bushing for hole i is prop-
erly aligned with the drill. The casting is located in this jig
by the inner ends of the two guide bushings w and the bushing
o and also by two locating screws p and a side locating screw q.
Adjustable screws t and t\ in the cover hold the casting down,
and it is held laterally by the two knurled thumb-screws u
and v. If an attempt were made to drill this particular part
without a jig (as would be done if only a few castings were
needed) it would have to be set with considerable care, provided
the angle between hole i and those in the base had to be at
all accurate, and it would be rather difficult to drill a number
of these castings and have them all duplicates. By the use of
a jig, however, designed for drilling this particular casting,
the relative positions of the holes in any number of parts are
practically the same and the work can be done much more
quickly than would be possible if it were held to the drill-press
table by ordinary clamping appliances. Various designs of jigs
will be described in Chapter VII.

Details of Jig Design. The general principles of the design
and use of jigs have been explained. The details of jig design
will now be considered. Generally speaking, the most im-
portant parts of a jig are the guide bushings for the drills and
other tools, the clamping devices, and the locating points,
against which the work is placed to insure an accurate posi-
tion in the jig. The guides for the cutting tools in a drill jig
take the form of concentric steel bushings, which are placed in
the jig body in proper positions.

The drill bushings are generally made of tool steel, hardened
and lapped, and, where convenient, should be ground inside
and out. They should also be long enough to support the
drill on each side regardless of the fluting, and they should be
so located that the lower end of the bushings will stop about
the same distance above the work as the diameter of the drill,
so that chips will clear the bushings readily. Where holes are
drilled on the side of a convex or a concave surface, the end of
the bushing must be cut on a bevel and come closer to the part
being drilled, to insure the drill having adequate support while
starting into the work. The bushings should have heads of
sufficient diameter. Long bushings should be relieved by in-
creasing the hole diameter at the upper end. The lower end
of the bushing should have its edges rounded, in order to permit
some of the chips being shed from the drill easily, instead of
all of them being forced up through the bushing. It is also
good practice to cut a groove under the head for clearance for
the wheel when grinding the bushing on the outside. A com-
plete treatise covering dimensions and design is given in the
chapter on "Jig Bushings."

In order to hold the work rigidly in the jig, so that it may
be held against the locating points while the cutting tools
operate upon the work, jigs and fixtures are provided with
clamping devices. Sometimes a clamping device serves the
purpose of holding the jig to the work, in a case where the
work is a very large piece and the jig is attached to the work
in some suitable way. The purpose of the clamping device,
however, remains the same, namely, that of preventing any
shifting of the guiding bushings while the operation on the
work is performed. The clamping device should always be an
integral part of the jig body in order to prevent its getting lost.
Different types of clamping devices are shown and described
in the chapter on "Jig Clamping Devices. "

The locating points may consist of screws, pins, finished
pads, bosses, ends of bushings, seats, or lugs cast solid with
the jig body, etc. The various types used are described in
detail in the chapter on "Locating Points and Adjustable
Stops."

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