Thursday, August 23, 2018

F.W. Taylor - Shop Management - Essays with Links

Halsey Plan - F.W. Taylor's Comments
http://nraoiekc.blogspot.com/2013/08/halsey-plan-fw-taylors-comments.html



Shop Management - Themes

1. Definition of Management 

2. Difference in Production Quantity between a first class man and an average man

3. Developing and Employing First Class People in an Organization

4. Confronting Soldiering - Slow Pace of Work

5. Halsey Plan - F.W. Taylor's Comments

6. Task Management

7. Investment for Increasing Productivity or Efficiency

8. Importance of people - organization

9. Modern Engineering and Modern Shop Management

10. Task Management - Starting and Ending Times

11. Task Work - Some More Thoughts

12. Usefulness of Gantt's system

13. Time Study by F.W. Taylor

14. Bicylcle Ball Inspection Case Study

15. Need for Functional Foremanship or Functional Organisation of Foremen

16. Functional Foremanship

17. Production Planning and Control

18. Role of Top Management in Managing Change to High Productive Shop

19. Train Operators in High Productivity One by One and Then in Small Batches

20. Organizing a Small Workshop for High Productivity

21. Introducing Functional Foremanship

22. Personal Relations Between Employers and Employed

23. Don't be in a hurry - It Takes Time to Manage Change

24. Best Practices in Shop Management



Interteresting to note

New Shop Floor Management - by Kiyoshi Suzaki
https://books.google.co.in/books?id=WM1b8NXzYZ4C&printsec=frontcover#v=onepage&q&f=false


Updated 24 August 2018
29 March 2016

Productivity Methods Training - Principle of Industrial Engineering





TAYLOR - NARAYANA RAO PRINCIPLES OF INDUSTRIAL ENGINEERING




Productivity Methods Training


_________________


Taylor emphasized the importance of training in creating a change in the systems of an organization in his writings. The following discussion is from Shop Management.

The most important and difficult task of the organizer (of change)  will be that of selecting and training the various functional foremen who are to lead and instruct the workmen, and his success will be measured principally by his ability to mold and reach these men. They cannot be found, they must be made. They must be instructed in their new functions largely, in the beginning at least, by the organizer himself; and this instruction, to be effective, should be mainly in actually doing the work. Explanation and theory will go a little way, but actual doing is needed to carry conviction.

To illustrate: For nearly two and one-half years in the large shop of the Bethlehem Steel Company, one speed boss after another was instructed in the art of cutting metals fast on a large motor-driven lathe which was especially fitted to run at any desired speed within a very wide range. The work done in this machine was entirely connected, either with the study of cutting tools or the instruction of speed bosses. It was most interesting to see these men, principally either former gang bosses or the best workmen, gradually change from their attitude of determined and positive opposition to that
in most cases of enthusiasm for, and earnest support of, the new methods. It was actually running the lathe themselves according to the new method and under the most positive and definite orders that produced the effect. The writer himself ran the lathe and instructed the first few bosses. It required from three weeks to two months for each man.
http://nraoiekc.blogspot.com/2013/08/train-operators-in-high-productivity.html

Principles of Industrial Engineering - Presentation 


by Dr. K.V.S.S. Narayana Rao in the 2017Annual Conference of IISE (Institute of Industrial and Systems Engineering) at Pittsburgh, USA on 23 May 2017

______________________________


______________________________


Updated on 24 August 2018
First published on 6 July 2017

Cost Reduction - Indian Companies


ET 500 List

https://economictimes.indiatimes.com/marketstats/pageno-1,pid-58,sortby-CurrentYearRank,sortorder-asc,year-2017.cms


We have a good visibility on cost reduction in FY18: Girish Wagh, Tata Motors
We are  doing value engineering (reducing the cost of a part without reducing the value to the customer) and value analysis (increase value delivered at the same cost).
9 November, 2017, Business Standard
https://www.tatamotors.com/media-press-coverage/we-have-a-good-visibility-on-cost-reduction-in-fy18-girish-wagh-tata-motors/

Artificial Intelligence - A Note for Industrial Engineers for Industrial Engineering 4.0 (IE 4.0)



Artificial Intelligence (AI) is explained by PWC as  a collective term for computer systems that can sense their environment, think, learn, and take action in response to what they’re sensing and
their objectives.

 AI is in use today in actual devices or systems like digital assistants, chatbots and machine learning
amongst others.

The intelligence included in AI can be categorized as:

Automated intelligence: Automation of manual/cognitive and routine/nonroutine tasks.
Assisted intelligence: Helping people to perform tasks faster and better.
Augmented intelligence: Helping people to make better decisions.
Autonomous intelligence: Automating decision making processes without human intervention.

More AI innovations are likely to come out of the research lab and the transformational possibilities are staggering based on the various research and development proposals announced or indicated.



2018

Transforming manufacturing with artificial intelligence
August 22, 2018 | Written by: Dr. Jongwoon Hwang, Group Leader, KIST Europe and Marco Hüster, Business Lead AI Implementation, KIST Europe
https://www.ibm.com/blogs/cloud-computing/2018/08/22/manufacturing-artificial-intelligence/

AI applications Today?
June 24, 2018
Visual Recognition (Face recognition, automatic tagging, metadata, video indexing)
Speech to Text
Text to Speech
Language Translation
Natural Language Classification and Processing
Cognitive Content Moderation
Voice Recognition
Recommendation Engines and Semantic Search
Photo Filtering and Enhancement
Sentiment Analysis (Social media, email, etc.)
Automate Workflows
Pattern Matching and Pattern Finding
https://www.shellypalmer.com/2018/06/5-ai-clouds-can-use-today/

PWC Report on AI
2017

Sizing the prize: What’s the real value of AI for your business and how can you capitalise?

https://www.pwc.com/gx/en/issues/analytics/assets/pwc-ai-analysis-sizing-the-prize-report.pdf



A Very Short History Of Artificial Intelligence (AI)
https://www.forbes.com/sites/gilpress/2016/12/30/a-very-short-history-of-artificial-intelligence-ai/

Cambrian Intelligence: The Early History of the New AI

Rodney Allen Brooks
MIT Press, 1999 - Computers - 199 pages
Until the mid-1980s, AI researchers assumed that an intelligent system doing high-level reasoning was necessary for the coupling of perception and action. In this traditional model, cognition mediates between perception and plans of action. Realizing that this core AI, as it was known, was illusory, Rodney A. Brooks turned the field of AI on its head by introducing the behavior-based approach to robotics. The cornerstone of behavior-based robotics is the realization that the coupling of perception and action gives rise to all the power of intelligence and that cognition is only in the eye of an observer. Behavior-based robotics has been the basis of successful applications in entertainment, service industries, agriculture, mining, and the home. It has given rise to both autonomous mobile robots and more recent humanoid robots such as Brooks' Cog.

This book represents Brooks' initial formulation of and contributions to the development of the behavior-based approach to robotics. It presents all of the key philosophical and technical ideas that put this "bottom-up" approach at the forefront of current research in not only AI but all of cognitive science.
https://books.google.co.in/books?id=btvRZ5rj51EC


Updated on 24 August 2018
20 February 2018

Wednesday, August 22, 2018

Engineering Optimization - Courses and Resources


Engineering Optimization - Journal - Current Issue

___________




Source: http://www.tandfonline.com/toc/geno20/current  - downloaded on 17 June 2015
___________


Seminar Papers of   Altair

https://www.altairatc.com/india/previous-events/atc/2017/2017-Technical-Papers.htm

https://www.altairatc.com/india/previous-events/atc/index.htm





Northwestern Engineering Course
http://www.mech.northwestern.edu/courses/descriptions/441-engineering-optimization-for-product-design-and-manufacturing.html

NPTEL Course
http://nptel.iitm.ac.in/courses/112106064/


Kelvin's Law of Economic Size of Conductor (Engineering Economics by Taylor)


Optimization of Helical Spring - Gear - 2002 MS Thesis
http://etd.ohiolink.edu/send-pdf.cgi/DESHMUKH%20DINAR%20VIVEK.pdf?ucin1028738547

University of Maryland Course
http://www.enme.umd.edu/undergrad/courses/enme489D.html



2013

Seco Tools India article on metal cutting optimization
http://www.secotools.com/CorpWeb/india/pdf/Production%20economy1.%20Seco2.pdf


2012 Paper
On the Economics of Computer Assisted Numerically Controlled Cylindrical Turning Operations - Optimized Conditions for Maximum Rate of Profit.- - T.K. Jack and O.M.U. Etubu
http://www.ijetae.com/files/Volume2Issue4/IJETAE_0412_75.pdf

A review of optimization techniques in metal cutting processes
Indrajit Mukherjee , Pradip Kumar Ray,
a Department of Industrial Engineering and Management, Indian Institute of Technology, Kharagpur 721 302, India
Computers & Industrial Engineering
Volume 50, Issues 1–2, May 2006, Pages 15–34
http://www.sciencedirect.com/science/article/pii/S0360835205001403


OPTIMIZATION OF CUTTING PARAMETERS FOR CNC TURNED
PARTS USING TAGUCHI’S TECHNIQUE
http://annals.fih.upt.ro/pdf-full/2012/ANNALS-2012-3-86.pdf


Cutting Speed and Feed Rate Optimization for Minimizing
Production Time of Turning Process
S. S. K. Deepak
(Department of Mechanical Engineering, Rungta Engineering College, Raipur, Chhattisgarh, India)
International Journal of Modern Engineering Research (IJMER)
Vol.2, Issue.5, Sep-Oct. 2012 pp-3398-3401
http://www.ijmer.com/papers/Vol2_Issue5/BQ2533983401.pdf

2001

Multi-objective optimization of industrial hydrogen plants
J. K. Rajesh!, S. K. Gupta",1, G. P. Rangaiah!, A. K. Ray!,*
!Department of Chemical and Environmental Engineering, National University of Singapore, 10 Kent Ridge Crescent, Singapore 119260, Singapore
"Department of Chemical Engineering, University of Wisconsin, Madison, WI 53706, USA
Chemical Engineering Science 56 (2001) 999-1010


____________
Genetic Algorithms and Engineering Optimization
Mitsuo Gen, Runwei Cheng

John Wiley & Sons, 2000 - Computers - 495 pages
A comprehensive guide to a powerful new analytical tool by two of its foremost innovators

The past decade has witnessed many exciting advances in the use of genetic algorithms (GAs) to solve optimization problems in everything from product design to scheduling and client/server networking. Aided by GAs, analysts and designers now routinely evolve solutions to complex combinatorial and multiobjective optimization problems with an ease and rapidity unthinkable withconventional methods. Despite the continued growth and refinement of this powerful analytical tool, there continues to be a lack of up-to-date guides to contemporary GA optimization principles and practices. Written by two of the world's leading experts in the field, this book fills that gap in the literature.

Taking an intuitive approach, Mitsuo Gen and Runwei Cheng employ numerous illustrations and real-world examples to help readers gain a thorough understanding of basic GA concepts-including encoding, adaptation, and genetic optimizations-and to show how GAs can be used to solve an array of constrained, combinatorial, multiobjective, and fuzzy optimization problems. Focusing on problems commonly encountered in industry-especially in manufacturing-Professors Gen and Cheng provide in-depth coverage of advanced GA techniques for:
* Reliability design
* Manufacturing cell design
* Scheduling
* Advanced transportation problems
* Network design and routing

Genetic Algorithms and Engineering Optimization is an indispensable working resource for industrial engineers and designers, as well as systems analysts, operations researchers, and management scientists working in manufacturing and related industries. It also makes an excellent primary or supplementary text for advanced courses in industrial engineering, management science, operations research, computer science, and artificial intelligence.
Google book link with preview facility
http://books.google.co.in/books?hl=en&lr=&id=U7MuV1q6P1oC
______________________



Updated  23 August 2018
18 June, 23 May 2015
First publisedh  29 6 2013

Sunday, August 19, 2018

Manufacturing Processes - Recent Introductory Textbook Topics


Manufacturing Processes



Individuals who will be involved in design and manufacturing of finished products need to understand the grand spectrum of manufacturing technology. Comprehensive and fundamental, Manufacturing Technology: Materials, Processes, and Equipment introduces and elaborates on the field of manufacturing technology—its processes, materials, tooling, and equipment. The book emphasizes the fundamentals of processes, their capabilities, typical applications, advantages, and limitations. Thorough and insightful, it provides mathematical modeling and equations as needed to enhance the basic understanding of the material at hand.

Designed for upper-level undergraduates in mechanical, industrial, manufacturing, and materials engineering disciplines, this book covers complete manufacturing technology courses taught in engineering colleges and institutions worldwide. The book also addresses the needs of production and manufacturing engineers and technologists participating in related industries.

Manufacturing Technology: Materials, Processes, and Equipment
Helmi A. Youssef, Hassan A. El-Hofy, Mahmoud H. Ahmed

March 29, 2017 by CRC Press
Reference - 948 Pages
https://www.crcpress.com/Manufacturing-Technology-Materials-Processes-and-Equipment/Youssef-El-Hofy-Ahmed/p/book/9781138072138

Heat Treatment of Metals and Alloys
Introduction
Heat Treatment of Steels
Basic Heat Treatment Operations of Steels
Heat Treatment of Cast Iron
Heat Treatment of Nonferrous Alloys and Stainless Steels
(Precipitation Hardening)

Smelting of Metallic Materials
Introduction
Smelting of Ferrous Metals
Smelting and Extraction of Nonferrous Metals

Casting of Metallic Materials
Introduction and Classification
Historical Development of Casting
Expendable Mold Casting Processes
Permanent Mold Castings
Melting Furnaces
Cleaning and Finishing of Castings
Quality of Castings
Modeling of Casting

Fundamentals of Metal Forming
Introduction
Simple Stresses and Strains
Two- and Three-Dimensional Stresses and Strains
Yield Criteria
General Plastic Stress–Strain Relations (Theory of Plasticity)
Effect of Temperature on Plastic Deformation
Cold, Warm, and Hot Forming
Effect of Strain Rate on Plastic Deformation
Superplasticity
Effect of Friction and Lubrication in Metal Forming

Bulk Forming of Metallic Materials
Introduction
Classification of Forming Processes
Forging Processes
Rolling Processes
Extrusion
Rod, Wire, and Tube Drawing

Sheet Metal Forming Processes
Introduction and Classification
Shearing Processes
Bending Processes
Stretch Forming
Deep Drawing
Rubber Pad Forming (Flexible-Die Forming)
Hydroforming (Fluid-Forming Processes)
Spinning
Superplastic Forming of Sheets
Blow Forming and Vacuum Forming
Thermoforming Methods
Sheet Metal Formability

High-Velocity Forming and High-Energy-Rate Forming
Introduction and Classification
Characteristics of HVF and HERF Processes
High-Velocity Forming Machines
High-Energy-Rate Forming Processes
Future of HVF and HERF

Powder Metallurgy and Processing of Ceramic Materials
Introduction
Historical Development of Powder Metallurgy
Metal Powder Production
Powder Metal Characterization
Blending and Mixing of Powders
Powder Compaction
Sintering
Secondary Operations
Ceramic Materials
Ceramic Manufacturing Processes

Polymeric Materials and Their Processing

Introduction
Historical Development of Polymeric Materials
Polymerization
Thermoplastic Polymers (Thermoplastics TP)
Thermosetting Polymers (Thermosets)
Elastomers.
Thermoplastic Elastomers
Processing of Polymeric Materials

Composite Materials and Their Fabrication Processes

Introduction
Classification and Characteristics of Composites
Fiber-Reinforced Composites
Particulate Composite Materials
Laminated Composite Materials
Combinations of Composite Materials
Fabrication of Composite Materials
Molding Processes
Prepreg Fabrication
Filament Winding
Pultrusion

Fundamentals of Traditional Machining Processes

Introduction
Basics of Chipping Processes
Basics of Abrasion Processes

Machine Tools for Traditional Machining

Introduction
General Purpose Machine Tools
Special Purpose Machine Tools

Fundamentals of Nontraditional Machining Process

Introduction
Classification of Nontraditional Machining Processes
Jet Machining
Ultrasonic Machining
Chemical Machining
Electrochemical Machining
Electrochemical Grinding
Electric Discharge Machining
Electron Beam Machining
Laser Beam Machining
Plasma Arc Cutting
Concluding Characteristics of NTMPS

Numerical Control of Machine Tools

Introduction
NC Concepts
Movements in CNC Systems
Control of NC Machine Tools
CNC Machine Tools
Input Units
CNC Instructions
Program Format
Features of CNC Systems
Part Programming

Industrial Robots and Hexapods

Introduction
Industrial Robots
Hexapods

Surface Technology

Introduction
Surface Smoothing
Surface Cleaning
Surface Protection
Roll Burnishing and Ballizing
Deburring

Joining Processes

Introduction
Fusion Welding
Solid-State Welding
Solid–Liquid State Welding
Welding of Plastics
Metallurgy of Welded Joints
Welding Defects
Welding Quality Control
Mechanical Joining

Advanced Manufacturing Techniques

Introduction
Near Net Shape Manufacturing
Microfabrication Technology
Nanotechnology
Semiconductor Device Fabrication
Sustainable and Green Manufacturing

Materials, Processes, and Design for Manufacturing

Introduction
Function, Material, Process, and Shape Interaction
Manufacturing Process Capabilities
Process Selection Factors
Manufacturing Process Selection
Design for Manufacturing

Quality Control

Introduction
Statistical Quality Control
Total Quality Control
The ISO 9000 Standard
Dimensional Control
Measuring Quality Characteristics
Measuring Tools and Equipment
Coordinate-Measuring Machine
Surface Measurements
Nondestructive Testing and Inspection
Destructive Testing

Automation in Manufacturing Technology

Introduction
Mechanization versus Automation
Automation and Production Quantity
Necessity for Introducing Automation
Manufacturing Systems
Flexible Manufacturing Systems
Computer Integrated Manufacturing.
Integrated Manufacturing Production System-Lean Production
Adaptive Control
Smart Manufacturing and Artificial Intelligence
Factory of Future
Concluding Remarks Related to Automated Manufacturing


2011 Edition
https://books.google.co.in/books/about/Manufacturing_Technology.html?id=KGbNBQAAQBAJ


https://books.google.co.in/books/about/Machining_Technology.html?id=IleBqfaGK1oC


Updated on 20 August 2018
21 March 2018

Sunday, August 12, 2018

Productivity Improvement Process - Role of Science, Engineering, Industrial Engineering and Management

R.M. Currie who developed work study out of Motion and Times Study, described six steps as lines of attack to improve productivity.

1. Improve basic processes by research and development.
2. Improve existing, and provide new plant and equipment
3. Simplify and improve the product and reduce the variety.
4. Improve existing methods of plant operation.
5. Improve the planning of work and the use of manpower.
6. Increase the effectiveness of all employees

Work study has application in lines 4,5 and 6.


The Development and Scope of Work Study
R. M. Currie, M.I.C.E., First Published June 1, 1954 Research Article
Proceedings of the Institution of Mechanical Engineers
http://journals.sagepub.com/doi/abs/10.1243/PIME_PROC_1954_168_063_02?journalCode=pmea

What would be the role of industrial engineers in the lines of attack indicated by Currie? That answer is not available at the moment with me. I have to search if any industrial engineer has answered such a question.



Detailed List of Activities in Productivity Improvement Process




In principle,  increasing productivity of various economic activities is a responsibility shared by many intellectual and professional disciplines.

In engineering activities, we can identify, scientists, engineers, industrial engineers and managers as principal categories of professionals that have responsibility for increasing productivity of engineering activities.

We can identify the following as activities or tasks that are to be carried out to improve productivity in engineering activities. No doubt, industrial engineers have taken up the specialist responsibility of improving productivity in engineering activities. They describe themselves, efficiency engineers, productivity engineers, productivity service providers and management service providers.

An attempt is made to create a detailed list of activities to bring into focus many subjects that have a role to play in productivity improvement and industrial engineering activities.


Research


1. Research to create knowledge that helps development of new materials, products, equipment and processes.
2. Research that creates knowledge that helps in making existing products and processes more productive. Industrial engineering researchers have an important role in this type of research.
3.Research in the area of management

Development


3. Development of new materials, products, equipment  and processes.
4. Development of productivity improvement devices, attachments, tools and features.
5. Development process modifications that improve productivity.

Design


Design is scaling up the developed solutions to fit the dimensions of application. Design involves form design and strength design. The form design is based on the developed solution. Strength design is based on stress analysis and strength of the material being used. Concurrent industrial engineering needs to be practiced in this stage.

6. Design of new products that are more productive
7. Design of equipment that is more productive
8. Design of new processes that are more productive
9. Design of production systems that are more productive.
10. Design of management procedures that are more productive.
11. Using optimization in design
12. Using samples in processes.
13. Engineering economic analysis
14. Design of payment systems and incentive systems
15. Design of communication systems
16. Design of data processing system

Redesign


17. Replacement decision
18. Productivity analysis and engineering of products
19. Productivity analysis and engineering of processes
20. Productivity analysis and enhancement of equipment
21. Productivity analysis and enhancement of tools and accessories

Operations - Day to Day working


Production planning - IEs to evaluate and improve planning procedures.
Project planning - IEs to evaluate and improve planning procedures.
Employee involvement in productivity improvement suggestions.
Productivity improvement workshops, events


Saturday, August 11, 2018

Control of Staff Overhead



https://books.google.co.in/books?id=5yuuCwAAQBAJ&printsec=frontcover#v=onepage&q&f=false

Control of Staff-related Overhead

Arthur Brearley
Springer, 18-Jun-1976 - Business & Economics - 181 pages

Woodworking Tools



1. The claw Hammer
2. Tape measure
Utility knife
Moisture meter
Chisel
Level
Screwdriver
Nail set
Sliding bevel
Layout square

https://www.wagnermeters.com/moisture-meters/wood-info/top-40-woodworking-tools/

Written by Ron Smith

https://www.wagnermeters.com/top-40-woodworking-tools-2/

Machine Shop - Work Shop - Theory and Practice


Emmanuel Nino
https://books.google.co.in/books?id=0rmIflmI4AIC&printsec=frontcover#v=onepage&q&f=false


11. Engine lathe processes
12.
13. Boring
14. Drilling
15. Reaming
16. Threading
17
18. Shaping
19. Shearing
20. Milling
21. Grinding
22. Pressing

Workshop Theory and Practice
Rex Bookstore, Inc.
https://books.google.co.in/books?id=bbDwSMyyKe4C


11. Engine Lathe Processes


Page 26

Figure 24.
Kinds of machining that can be done on lathe

External threading
Parting
Turning
Facing
Tapering
Necking or grooving
Knurling
Radius
Bevel
Internal threading

Engino - Engineering and Technology Toys



https://www.enginotoys.com/


Increase your children's knowledge of engineering and technology by providing them Engino toys.

ABET Explanation - What is Engineering?

Definition given by The American Engineers' Council for Professional Development (ECPD, the predecessor of ABET

"The creative application of scientific principles to design or develop structures, machines, apparatus, or manufacturing processes, or works utilizing them singly or in combination;
or to construct or operate the same with full cognizance of their design;
or to forecast their behavior under specific operating conditions;
all as respects an intended function, economics of operation and safety to life and property.”

___________________

____________________



DEFINITION OF ENGINEERING/ENGINEERING TECHNOLOGY

According to the Accreditation Board for Engineering and Technology (ABET):

ENGINEERING is the profession in which a knowledge of the mathematical and natural
sciences gained by study, experience, and practice is applied with judgment to develop ways to
utilize economically the materials and forces of nature for the benefit of mankind.

ENGINEERING TECHNOLOGY is the part of the technological field that requires the
application of scientific and engineering knowledge and methods combined with technical skills
in support of engineering activities; it lies in the occupational spectrum between the craftsman
and the engineer at the end of the spectrum closest to the engineer.

https://wmich.edu/engineer/ceee/miller/082903/Lecture%20Notes.pdf


______________________
Engineering is the creative application of knowledge:
to design or develop structures, machines, apparatus, or manufacturing processes,
or works utilizing them singly or in combination;
or to construct or operate the same with full cognizance of their design;
or to forecast their behavior under specific operating conditions,

--------------------------------

Student Outcomes
The program must have documented student outcomes that prepare graduates to attain the program educational objectives.
Student outcomes are outcomes (a) through (k) plus any additional outcomes that may be articulated by the program.
(a) an ability to apply knowledge of mathematics, science, and engineering
(b) an ability to design and conduct experiments, as well as to analyze and interpret data
(c) an ability to design a system, component, or process to meet desired needs within realistic constraints such as economic, environmental, social, political, ethical, health and safety, manufacturability, and sustainability
(d) an ability to function on multidisciplinary teams
(e) an ability to identify, formulate, and solve engineering problems
(f) an understanding of professional and ethical responsibility
(g) an ability to communicate effectively
(h) the broad education necessary to understand the impact of engineering solutions in a global, economic, environmental, and societal context
(i) a recognition of the need for, and an ability to engage in life-long learning
(j) a knowledge of contemporary issues
(k) an ability to use the techniques, skills, and modern engineering tools necessary for engineering practice.

http://www.abet.org/accreditation/accreditation-criteria/criteria-for-accrediting-engineering-programs-2018-2019/

Definitions

Complex Engineering Problems
Complex engineering problems include one or more of the following characteristics: involving wide-ranging or conflicting technical issues, having no obvious solution, addressing problems not encompassed by current standards and codes, involving diverse groups of stakeholders, including many component parts or sub-problems, involving multiple disciplines, or having significant consequences in a range of contexts.

Engineering Design
Engineering design is a process of devising a system, component, or process to meet desired needs and specifications within constraints. It is an iterative, creative, decision-making process in which the basic sciences, mathematics, and engineering sciences are applied to convert resources into solutions. Engineering design involves identifying opportunities, developing requirements, performing analysis and synthesis, generating multiple solutions, evaluating solutions against requirements, considering risks, and making trade- offs, for the purpose of obtaining a high-quality solution under the given circumstances. For illustrative purposes only, examples of possible constraints include accessibility, aesthetics, codes, constructability, cost, ergonomics, extensibility, functionality, interoperability, legal considerations, maintainability, manufacturability, marketability, policy, regulations, schedule, standards, sustainability, or usability.

Engineering Science
Engineering sciences are based on mathematics and basic sciences but carry knowledge further toward creative application needed to solve engineering problems. These studies provide a bridge between mathematics and basic sciences on the one hand and engineering practice on the other.


Work Study - Evolution - Bibliography

The Development and Scope of Work Study
R. M. Currie, M.I.C.E., First Published June 1, 1954 Research Article
Proceedings of the Institution of Mechanical Engineers
http://journals.sagepub.com/doi/abs/10.1243/PIME_PROC_1954_168_063_02?journalCode=pmea


http://www.managers-net.com/methodstudy.html

http://www.managers-net.com/Biography/Currie.html

(1965) "Work Study Volume 14 Issue 12", Work Study, Vol. 14 Issue: 12, pp.9-72, https://doi.org/10.1108/eb048202
https://www.emeraldinsight.com/doi/abs/10.1108/eb048202

E.M.R. DITMAS,
Aslib organized a series of meetings in London during the autumn and winter of 1951–2. The first of these was held on 7th November, 1951, at Chaucer House, when Mr. J. P. Torrie, Work Study Officer of the Work Study Section, Technical Department, Imperial Chemical Industries, Ltd., spoke on Method Study.
https://www.emeraldinsight.com/doi/abs/10.1108/eb049429


J.F. Payne
October 1963

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1559-3584.1964.tb04763.x

WORK STUDY IN INDUSTRY
S. J. Dalziel
First published: July 1956
https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1467-923X.1956.tb01522.x

The Meaning of Work: Papers on Work Organization and the Design of Jobs
By Lisl Klein
Lisl Klein worked on thesis human implications of work study
https://books.google.co.in/books?id=W_eH2J3DdpQC&pg=2#v=onepage&q&f=false


Scientific Management in Britain, A History
PhD Thesis
1995
Kevin Whitston
http://wrap.warwick.ac.uk/3981/1/WRAP_THESIS_Whitston_1995.pdf


Management of Productivity Hardcover – 1971
by Joseph E. Faraday  (Author)
https://www.amazon.com/Management-Productivity-Joseph-Faraday/dp/0851180787


Impact of Productivity Linked Reward Systems PLRS on the service sector
Researcher: Dhaka, Brham Pal
Guide(s): Goyal, O P
University: Maharshi Dayanand University
Completed Date: 31/12/1996
http://shodhganga.inflibnet.ac.in/handle/10603/132453


https://books.google.co.in/books?id=uKFlAgAAQBAJ&pg=PA151#v=onepage&q&f=false

Scientific method
https://books.google.co.in/books?id=zRpUAQAAQBAJ&pg=PT33#v=onepage&q&f=false



Principles of Work Study and Employee Productivity
Readings in Personnel Management
K.V. Ramani - Volume with focus on productivity
https://books.google.co.in/books?id=MQHqQao8pJEC&pg=PA145#v=onepage&q&f=false


"Time and Motion Study", Work Study, Vol. 3 Issue: 11, 1954, pp.11-51,

Time and Motion Study, as its name implies, has always advocated the integration of all Work Study interests. It has always held the view that Motion Study and Time Study are complementary to one another.
https://www.emeraldinsight.com/doi/abs/10.1108/eb048070?journalCode=ws

Introductory Talk: The Practical Application of Work Study and Incentives to Maintenance Engineering on Continuously Operated Plants
I. S. McDavid, First Published June 1, 1963 Other

Proceedings of the Institution of Mechanical Engineers, Conference Proceedings
http://journals.sagepub.com/doi/abs/10.1243/PIME_CONF_1963_178_185_02?journalCode=pcpa

Friday, August 10, 2018

What is Engineering Method?



What is Engineering?
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Engineering method is the topic explained in the book:

Discussion of the Method
Conducting the Engineer's Approach to Problem Solving

Billy Vaughn Koen

Publication Date - March 2003

ISBN: 9780195155990


"The best description of engineering that I have ever seen, and one of the most provocative hypotheses about science and nature that I have ever seen!"--Dr. William A. Wulf, President, National Academy of Engineering.

https://global.oup.com/ushe/product/discussion-of-the-method-9780195155990




"While the study of the engineering method is important to create the world we would have, its study is equally important to understand the world we do have."

--Billy V. Koen, Introduction, Discussion of the Method

Discussion of the Method outlines the heuristic-based reasoning used by engineers and generalizes it to a universal method for problem-solving. Delving into the connection between engineering and philosophy, this text illustrates how the theoretical and the practical can merge to form real-world solutions. The book can be used in  introductory and advanced courses in engineering, philosophy, and other disciplines. It also a compelling read for practicing engineers and general audiences.

AN OVERVIEW OF THE BOOK

Part I describes the problem situation that calls for the talents of the engineer and emphasizes how frequently this situation is encountered.
Part II defines the heuristic and the engineering method.
Part III lists examples of heuristics and techniques used to implement the engineering method, describes several alternative definitions of the engineering method, and renders the method in its final form.
Part IV generalizes the engineering method to a universal method.
Part V gives a concise, justifiable statement of universal method.
Part VI delivers a specific example of the universal method in use.

Table of Contents



Preface

Introduction

1. Some Thoughts on Engineering
1.1. The Engineer
1.2. Characteristics of an Engineering Problem
1.2.1. Change
1.2.2. Resources
1.2.3. Best
1.2.4. Uncertainty
1.3. Example Engineering Problems

2. The Principal Rule of the Engineering Method
2.1. Definition of Engineering Design
2.2. The Heuristic
2.2.1. Definition
2.2.2. Signatures of the Heuristic
2.2.3. Synonyms of the Heuristic
2.2.4. Examples of Engineering Heuristics
2.3. State of the Art
2.3.1. Definition
2.3.2. Evolution
2.3.3. Transmission
2.3.4. An Acronym for State of the Art
2.3.5. Example Uses of the SOTA
2.3.6.1. Comparison of Engineers
2.3.6.2. Rule of Judgement
2.3.6.3. Engineer and Society
2.4. Principal Rule of the Engineering Method

3. Some Heuristics Used by the Engineering Method
3.1. Definition of Engineering Design
3.2. The Heuristic Method
3.3. Nature of Our Argument
3.3.1. Induction as a Heuristic
3.4. Representative Engineering Heuristics
3.4.1. Rules of Thumb and Orders of Magnitude
3.4.2. Factors of Safety
3.4.3. Attitude Determining Heuristics
3.4.3. Risk-Controlling Heuristics
3.4.4. Miscellaneous Heuristics
3.5. Alternate Definitions of Engineering
3.5.1. Engineering and Morphology
3.5.2. Engineering and Applied Science
3.5.3. Engineering and Trial and Error
3.5.4. Engineering and Problem Solution
3.6. Nature as a Designer
3.7. Preferred Definition of the Engineering Method
3.7.1. Time as a Heuristic
3.7.2. Derivation to a Curve
3.7.3. Reduction to a Preferred Form
3.7.4. Justification of the Heuristic Definition of the Engineering Method
3.8. Engineering Worldview
3.8.1. Coordinate Systems
3.8.2. Turtle Graphics
3.8.3. Consistent Engineering Worldview

4. The Universale Organum
4.1. Difficulties in Explaining the Koan
4.1.1. General Difficulties
4.1.2. Language as a Heuristic
4.2. Compelling Belief in KOAN
4.2.1. Basic Approach to Compel Belief
4.2.2. My Program
4.2.3. Weaving a Tapestry
4.2.3.1. Arithmetic as Arithmetic
4.2.3.2. Mathematics as Mathematics
4.2.3.3. Deduction as Deduction
4.2.3.4. Certain as Certain
4.2.3.5. Position as Position
4.2.3.6. Logic as Logic
4.2.3.7. Truth as Truth
4.2.3.8. Progress as Progress
4.2.3.9. Causality as Causality
4.2.3.10. Consciousness as Consciousness
4.2.3.11. Physical Reality as Physical Reality
4.2.3.12. Science as Science
4.2.3.13. Perception as Perception
4.2.4. Experto Credite
4.2.4.1. Argument as Argument
4.2.5. All Is Heuristic
4.2.6. Reduction of Koan to a Preferred Form
4.2.6.1. All
4.2.6.2. Is
4.2.6.3. Heuristic
4.3. Comparison of Heuristic and Skeptical Positions
4.3.1. History of Skepticism
4.3.2. Differences between Skeptic and Engineer
4.3.2.1. Génie Malin
4.3.2.2. Coherence
4.3.2.3. Home Field Advantage
4.3.2.4. Skeptic's Pride
4.3.2.5. Reification of Doubt
4.3.3. An Impregnable Defense
4.4. Overall SOTA
4.4.1. Synonyms
4.4.2. Partitioning Overall SOTA
4.4.2.1. Concepts as Subsets
4.4.2.2. Fuzzy Subsets
4.4.3. Personal SOTAs
4.4.3.1. Compelling Nature of Personal SOTA
4.4.3.2. Incoherence of Personal Sota
4.4.3.3. Rules of Judgement and Implementation
4.4.3.4. Engineer's Ataraxia
4.5. A Discourse on Method
4.5.1. Method of Descartes
4.5.2. Problems with Descartes' Method
4.5.2.1. Universal
4.5.2.2. Comprehensive
4.5.2.3. Prior Philosophical Commitment
4.5.2.4. Self Sufficient
4.5.3. Universal Organum
4.6. Engineering, Philosophy, and the Universal Method

5. Summary of the Method

6. Application of the Method
6.1. Traditional Utopia
6.2. Utopia as a Program for Change
6.3. Eutopia
6.4. Mundus Institute of Technology
6.4.1. Origins
6.4.2. Architecture
6.4.3. Personnel
6.4.3.1. Abstractors
6.4.3.2. Professors
6.4.3.3. Students
6.4.4. Research in Progress
6.4.4.1. Research in the Vestibule
6.4.4.2. Research in the Corridors

An Anachronistic Preface

Heuristics

Index

About the Author

Billy V. Koen is Professor of Mechanical Engineering at the University of Texas at Austin and a fellow of both the American Nuclear Society (ANS) and the American Society of Engineering Education (ASEE). He has received fifteen awards for teaching excellence, including the W. Leighton Collins Award, (the ASEE's highest honor for pedagogy), and the ASEE Centennial Medallion for his lasting impact on the field of engineering education. He is a pioneer in the application of artificial intelligence to nuclear reactor reliability and the introduction of self-paced teaching strategies in engineering education. He has written more than 125 technical publications and has contributed to numerous textbooks and engineering journals.

Included in his body of work is the classic treatise, "Definition of the Engineering Method," published by the ASEE in 1985.

Tuesday, August 7, 2018

Methods Efficiency Analysis of Setups


In this article, work place means work station layout issues are discussed. The issue of collecting drawings, materials and tools as well as instructions from appropriate persons are discussed. Then the machine set up and loading of  the work piece are discussed. After the processing operation is over, the work piece has to be unloaded and it has to be moved to the next stage. At the end of the day, tools etc. are to be returned. In the process, care has to be taken to see that equipment is kept in proper order. All issues are raised in the check list of questions given below. Effort will be made after some time to sort the questions into more appropriate sections.

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The setup or the workplace layout or both must be studied in detail, for they largely determine the methods and motions that must be used to perform the operation. The order in which tools are set up in a turret lathe, for example, will determine the order in which the various machining operations are performed. The position in which material is placed with respect to the point of use will determine the class and the length of the motions required to secure it.

Before any work can be done, certain preliminary or "make- ready" operations must be performed. These include such elements as getting tools and drawings, getting material and instructions, and setting up the machine or laying out material and tools about the workplace. When the operation itself has been completed, certain clean up or " put-away " elements must be done such as putting away tools and drawings, removing finished material, and cleaning up the workplace or machine.

Questions on "Make-ready" and "Put-away" Elements. The procedure followed to perform the " make-ready" and "put- away" elements should be questioned closely, particularly on small-quantity work, for these operations are usually fairly long. Many of them carry the operator away from his workplace. This is undesirable for several reasons, and the necessity for trips to other parts of the department should be minimized. The arrangement of the setup or the workplace layout is of primary importance, and the simple rules governing efficient workplace layouts should be clearly understood.

Typical questions which will lead to suggestions for improvement in this connection are as follows :

1. How is the job assigned to the operator?

2. Is the procedure such that the operator is ever without a job to do?

3. How are instructions imparted to the operator?

4. How is material secured?

5. How are drawings and tools secured?

6. How are the times at which the job is started and finished checked?

7. What possibilities for delays occur at drawing room, tool- room, storeroom, or time clerk's office?

8. If operator makes his own setup, would economies be gained by providing special setup men?

9. Could a supply boy get tools, drawings, and material?

10. Is the layout of the operator J s locker or tool drawer orderly so that no time is lost searching for tools or equipment?

11. Are the tools that the operator uses in making his setup adequate?

12. Is the machine set up properly?

13. Is the machine adjusted for proper feeds and speeds?

14. Is machine in repair, and are belts tight and not slipping?

15. If vises, jigs, or fixtures are used, are they securely clamped to the machine?

16. Is the order in which the elements of the operation are performed correct?

17. Does the workplace layout conform to the principles that govern effective workplace layouts?

18. Is material properly positioned?

19. Are tools prepositioned?

20. Are the first few pieces produced checked for correctness by anyone other than the operator?

21. What must be done to complete operation and put away all equipment used?

22. Can trip to return tools to toolroom be combined with trip to get tools for next job?

23. How thoroughly should workplace be cleaned?

24. What disposal is made of scrap, short ends, or defective parts?

25. If operation is performed continuously, are preliminary operations of a preparatory nature necessary the first thing in the morning?

26. Are adjustments to equipment on a continuous operation made by the operator?

27. How is material supply replenished?

28. If a number of miscellaneous jobs are done, can similar jobs be grouped to eliminate certain setup elements?

29. How are partial setups handled?

30. Is the operator responsible for protecting workplace over- night by covering it or locking up valuable material?

From this list, it may be seen that an analysis of "make-ready " and "put-away" operations covers a rather wide field. The general plant routine with respect to the way jobs are given out is questioned, as is also the manner in which tools, drawings, and materials are secured. Much of this is standard for every job; and after it has been thoroughly analyzed for one job and improved as much as possible, it need not be considered so carefully again. Too often, however, procedures of this sort have been hurriedly set up or were not set up at all. In the older shops which were in operation before the principles of scientific management were evolved, the routine in effect today may be merely bad habits. Therefore, the subject should receive a thorough analysis at least once, and preferably so that irregularities will not be permitted to creep in and become standard practice more often, say at least every 6 months.

Make Ready. The methods followed in giving out jobs differ widely throughout industry. Where the same operation is worked day after day, the problem is not encountered; but on more miscellaneous work, some procedure for telling an operator what job he is to work upon next must be provided.

When the operator has received notification in one way or another of the job he is to do, he must next secure drawings, tools, and material. The way in which this is done also varies widely. In some cases, the operator must hunt everything for himself. In others, he goes to a tool- or drawing-room window and waits while an attendant gets what he requires. In still other cases, everything is brought to him, and he does not have to leave his work station.

The exact procedure that is followed will depend upon existing conditions; but if it is possible to work out an economical system for furnishing the operator with what he needs at his work station, it is desirable to do so. Besides reducing costs, this procedure increases the amount of time the equipment is utilized and thus increases the productive capacity of the plant. Often a low-rated worker can do the errands of the operators and bring tools, drawings, and materials.

Where the group system is used and no supply boy is available, the group leader commonly gets all necessary supplies and tools. By getting the necessary items for several jobs at one time, he is able to effect economies.

If a conveyer system of the type illustrated in the preceding chapter is used, the jobs may be dispatched by the production department in the order wanted, and all material, tools, and drawings can be sent out at the same time on the conveyer. Thus the amount of time spent by the operator in
getting ready to make the setup or workplace layout is reduced to a minimum.

The manner in which instructions are furnished with regard to how the job should be done is worthy of careful consideration. In many cases, no instructions at all are given. The operator is supposed to be familiar enough with the work to know how to do it. If not, he may ask the foreman. When no definite instructions are given or when the foreman gives only brief general advice, the method that the operator follows is likely to be one of his own devising which may or may not be efficient. The fact that in so many cases different operators follow different methods in doing the same operation may be traced directly to insufficient instruction. To secure efficient performance, the best method must first be worked out and then taught.

Some plants employ instructors or demonstrators to perform the teaching function. If these men know the best methods themselves and are good teachers, good results will be secured. Too often, however, the instructor is merely an experienced operator who knows only such methods as he himself used before he was promoted. Even though he was a highly skilled operator, the chances of his knowing and being able to impart a knowledge of the best methods are small, unless he has received additional training himself in the principles of methods engineering. If he is a machine instructor, he is likely to teach feeds and speeds and the best way to grind tools, mentioning only briefly, if at all, the arrangement of the workplace and the motions that should be used.

Feeds, speeds, and the grinding of tools all are important, of course, but they constitute only part of the method. A lathe operator, for example, was engaged in turning shafts in an engine lathe. Each shaft had to be stamped with a number. The operator would remove a finished shaft from his lathe, turn to a bench, stamp the number, set aside the shaft, pick up another, and return to his machine. The turning required a long cut under power feed. A much better method is as follows: While a cut is being taken, the operator gets the next shaft to be machined; he places it on the machine ways in a convenient position; as soon as the cut is taken, he removes the finished shaft and inserts the other; he starts the cut and then while the machine is running, stamps and lays aside the finished shaft. Thus, the machine runs nearly continuously, and idle time on the part of both the operator and the machine is reduced.

The better procedure described will, no doubt, seem obvious to the reader, and it is, of course, standard practice in many plants. At the same time, the other method is encountered frequently in plants that have given little attention to methods and methods instruction. An experienced lathe operator going from a plant where the first method was common practice to one where the second was in effect would find it difficult to make satisfactory earnings in the second plant. If he were the only one doing this operation and so could not learn the better method by observation, he would be likely to feel that the rate was too tight and would become discouraged. Instruction in some manner with regard not only to feeds and speeds but also with regard to the proper motion sequence would be necessary to correct his difficulty.

Instruction sheets can be used to instruct operators and, under certain conditions, their use is not too costly.  It gives complete and detailed instructions.

Setup. The setup of the machine and of any tools, jigs, or fixtures used should be studied in detail. The correctness and the adequacy of the setup should first be considered, followed by a brief review of the methods employed to make it. The correct setup is fixed by the nature of the operation, the nature of the part, the requirements of the job, and the mechanical features of the machine. Sometimes, it is possible to do a job in more than one way, and care should be taken to ascertain that the best way is being used.

When the setup is being made, certain tools are usually required. These should be suitable for the purpose. If each operator must make his own setup, he should be provided with the necessary tools. If only one or two wrenches are furnished to a group of 10 operators, for example, the time lost in hunting the wrenches and in waiting for a chance to use them will usually far offset the cost of additional equipment.

If setup men are employed to setup machines ahead of the operators, their setup work is to them fairly repetitive work, because they are performing the same elements day after day. It will therefore be desirable to treat it as such and to furnish the setup men with special-purpose quick-acting tools.

The Workplace Layout. The improvement of the layout of the workplace of the industrial worker is too often overlooked as a means for effecting operating economies. The layout of the workplace partly determines the method the operator must follow in doing a given task, and it almost wholly determines the motions he must employ. Since certain motions are more fatiguing and consume more time than others, it is quite possible to effect worth-while cost reductions merely by rearranging layouts. The rearrangement usually comes about as the result of detailed motion study. If the underlying principles which govern workplace layouts are understood by the analyst, however, a consideration of the workplace layout will show whether detailed motion study is likely to bring about improvement, and it may also suggest obvious improvements that can be put into effect immediately. For this reason, the principles which affect workplace layouts will be discussed briefly.

Two general concepts underlie workplace layouts. The first has to do with the classes of motions that a human being can make. There are five general classes, as follows:

1. Finger motions.

2. Finger and wrist motions.

3. Finger, wrist, and forearm motions.

4. Finger, wrist, forearm, and upper-arm motions.

5. Finger, wrist, forearm, upper-arm, and body motions.

It is usually stated that motions of the lower classes can be made more quickly and with less expenditure of effort than inotions of the higher classes. This, however, is true only when the motions are made under not greater than normal load over paths of approximately equal length. It might be possible by exerting a prodigious effort to lift a heavy object an inch or so with a finger movement; but the same object could be lifted the same distance in less time, and -with far less fatigue, by a finger, wrist, and forearm movement. Similarly, it may be seen that a short fourth-class motion can be made more quickly than a long third-class motion.

In applying the concept of motion classes to actual layouts, the attempt should be made to reduce all motions to the lowest possible class. This, of course, must be interpreted with common sense. In actual practice, with what has been said in the preceding paragraph kept in mind, there is no difficulty in recognizing the lowest practical class of motion that can be employed to accomplish any given task.

The lowest class of motion is the finger motion. If a job can be accomplished by using only finger motions, no further improvement can be made. The use of pure finger motions- only, however, is seldom practicable. In most  layouts, the aim will be to eliminate all body movements, to reduce many fourth-class motions to the third class, and to reduce the length of all motion paths.

The second concept underlying workplace layouts is that of normal and maximum working areas. The area in which the worker performs his operation should be kept at a minimum, as this automatically keeps the class of motions which must be used in the lower classifications.


The principles of efficient work areas should be applied to all lines of work, for they are universal. It is customary to think of them in connection with bench operations; but they can and should be applied to the arrangement of tools and materials around machines or on work such as molding, forging, and the like, and to the arrangement of levers, handwheels, and so on, when designing machine-tool equipment. When the imaginary boundary lines that limit the normal and maximum working areas in all planes are clearly visualized, it is quite easy to detect inefficient arrangements of workplaces and to know exactly what steps must be taken to. bring about improvement.


When an analysis is made of a specific operation, one of the most glaring faults commonly encountered lies in the arrangement of containers of raw and finished material. If the placement is left to the operators, a body motion will often be used for getting or laying aside material, because the operator sets the material containers on the floor or the bench or in some other place that is available but not particularly convenient. Figure 71 illustrates a condition of this kind. The operator has placed a box of unfinished material on the floor beside his press. Every time he gets a part, he must bend his body, or in other words, must make a fifth-class motion. If before beginning the operation he were to place a stool beside his press and set the raw material box on it as shown in Fig. 72, he could then get the parts with a fourth-class motion. Thus, the time required for the element "get part" is reduced, and fatigue is partly eliminated.

Put Away. The put-away elements usually consume less time than the make-ready elements. Tools are put away, the setup is torn down, and the workplace is more or less thoroughly cleaned up. Usually, some of the put-away elements can be combined with some of the make-ready elements for the next operation.

Tools for one operation, for example, may be returned to the toolroom when the tools for the next operation are obtained. The procedure that will prove most economical for the put-away elements will depend to a large extent upon the manner in which the make-ready elements are performed.

Where a number of similar operations are performed on a machine, it is sometimes possible to use 'the same or part of the same setup on two or more jobs. A part that is common to several assemblies may be ordered separately for each and appear on several different orders. If these orders are grouped, one setup will care for them all. Again, in milling-machine work, for example, it may be possible to use the same cutter for several different jobs. The elements of "get cutter from toolroom/ ; "place cutter on machine,  "remove cutter from machine" and "return cutter to toolroom" will thus be performed but once for the several jobs.

Where possibilities of this sort exist, provision should be made when setting up the make-ready and put-away routine so that the economies will be made. If the operator does not know what job he is to do next, if he must completely tear down his setup before going for another job, and if neither the foreman nor the dispatcher attempts to group similar jobs, advantage cannot be taken of partial setups. This is wasteful, of course, and every attempt should be made to secure the benefit of partial setups. Whether or not the operator is paid for the complete setup or only for that part which he actually makes depends upon the difficulty in controlling setups and upon whether or not the saving is due to the operator's own initiative.  In either case, more time is available for productive work which is a distinct gain.

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


Updated 8 August 2018,  4 July 2015
First posted  23 November 2013


PRINCIPLES OF JIG DESIGN



JIG AND FIXTURE DESIGN


CHAPTER I

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 locating a piece of work while machined, and are provided with necessary 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 employment 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 variation 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 obtained 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 manufacturing. 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 machinery. 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 wornout 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 practicee, involving 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 arc many operations in the building of a machine, which, if each machine were built individually, without the use of special tools, would recjuirt' 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 chea[)er cla.ss of labor, provided the jigs and fixtures arc properly designed and correctly made. Another possibility for saving, particidarly 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 product'd. In shops where a great many duplicate parts arc made, containing a number of drilled holes, multiple-spindle drills of conii)!icated design, which may be rather expensive as ri'gards first cost, are really cheaper, by far, than ordinary simple; drill pr<‘.sses.

Another advantage which has been gain(;d by tin; u.se of jigs and fixtures, and which should not be lost sight of in the enumeration of the points in favor of building maciiinery by t he use of special tools, is that the details of a machint; that has been provided with a complete equipment of accurate and durable jigs and fixtures can all be finished simultanijously in different departments of a large factory, without inconveni(;nce. thus making 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 oftentimes not very easy to decide. The word jig is frequently, although incorrectly, applied to any kind of a work-holding appliance 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 operation 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 classify 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. —  Whenever a jig is made for a component part of a machine, it is almost always required that a corresponding 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 advisable, 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.

There are some cases where it is not advisable to make two
jigs, one for each of the two parts which arc 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 u.sing the brackets
and bearings already assembled and fastened to the machine
body as guides.

One of the most important questions to be decided before making 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 one for which it is designed.


The judgment of the designer is, in every case, the most important 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 principles 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 surfaca-s when laying
out and planing. While jigs are most common!}- {)ro\-i(led with
four feet on each side, in some cases it is sulHcient 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 applit-d to the
tool are placed inside of the gc'ometrical iigure obtained by con-
necting, by lines, the points of location for the feet.

While it may seem that three feet arc preferahle to use, because
the jig will then always obtain a bearing on all the thn-e feet,
which it would not with four feet, if the table of the machine
were not absolutely plane, it is not tjuite .safe to us(* the smaller
number of supports, because a chip or .some other object is liabki
to come under one foot and throw the jig and the j>iece out of
line, without this being noticed by the o{)erat«r. If the same
thing happens to a jig with four feet, it will rock and invariably
cause the operator to notice the defect. If Iht' tal»le 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 sometime,s in the case
of cast-iron jigs, detachable feet are us(;d.

Materials for Jigs. — Opinions differ as to the relative merit.s
of cast iron and steel as materials from which tt> 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 l)e put
and the character of the work which it is to handle. For small
and medium sized work, such as typewriter, sewing nuichine,
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 cheai>er 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 b(»sed
and “spot finished” at the point where the busihings 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 fre-
quently 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 luittom
the jig, or lugs with a slot in them to tit the hutiy of T-holts, a
the common means for clamping fixtures to the table. F
boring jigs, it is unnecessary to provitie more than three sm
clamping points, as a greater number is likely to cause sun
springing action in the fixture. A sliglit si»ringiitg effect is almo
unavoidable, no matter how strong uml heavy the jig is. hut. 1
properly applying the clamiis, it is jHissilile to eunliiu> this sprin
ing within commercial limits.

Jigs should always be tested before they an- used, .so as
make sure that the guiding provisions are plaeeil in the rig
relation to the locating points and in pri>per relation to tar
other.

Summary of Principles of Jig Design.

1. Before planning the design of a tf»oi. eompare the etwt
production of the work with present tools with the expeeted et
of production, using the tool to he ntatle, and see that the i tist
building is not in excess of expeeted gain.

2. Before laying out the jig or fixture, decitk- ujuni the loei
ing points and outline a clantping arrangemetit.

3. Make all clamping anti binding tleviees as tjuick-acti
as possible.

4. In selecting locating points, see that two eomponent pai
of a machine can be located from corresjamtUng }Kiints uml si
faces.

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

6. For rough castings, make some of the Imating jam
adjustable.

7. Locate clamps so that they will Ih- in the best {wsttion
resist the pressure of the cutting tool when at work.

8. Make, if possible, all clami>s integral parts of the jig
fixture.

9. Avoid complicated clamping arrangements, which 1
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 con-
taining 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.

16. 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, owiau (i* the great variety of
shapes of the work to be drillecl. 'I'here are. lunveviT, t wo geiieru!
types that are most commonly used, the dit'fereiue between
them being very marked. I'hese tjjws may In- tiassiiieti as
open jigs and closed jigs, or box jigs. Sometimes the ojh'ii jigs
are called clamping jigs. The ojHm jigs usually have all the drill
bushings in the same plane, parallel witli one another, and art*
not provided with loose or removable walls or leaves, thereby
making it possible to insert the piece tt> he drilletl without any
manipulation of the parts of the jig. 'I’hese jigs are ttften of
such a construction that they are a{)pliecl to the work to he
drilled, the jig being placed on the work, rather than the work
being placed in the jig. The jig may he held ti> the iv«»rk by
straps, bolts, or clamps, but in many cases the jig fits into or
over some finished part of the work ami in this way the jig is
located and held in position.

The closed drill jigs, or box jigs, frequently resetnhh^ 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, tin-
piece to be drilled can be inserted in the jig only after tme 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, saew bushings, straps, or hook-bolts.


The combination drilling and boring jig is another type of
osed jig designed to serve both for drilling and l>0riiig ciperii"
tions. Before designing a combination drill and boring jig,
Ae relation between, and number of, the drilled and bored
holes mvst be taken mto consideration, and also the size of the
inece to be mtod. In case there is a great number of holes,
It may be of advantage to have two or even more jigs for the
piece, be^i^e it makes it easier to design and make the
Jig, and vety likely ^ give a better result. The holes drilled
OT bored m the first jig may be used as a means for locating the
piece m the jigs used later on. Combination drill and boring
Jigs axe not very well adapted for pieces of large size





13 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 .4 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 slu.wn at
B. An grinnlar projection on the jig tits closi'ly in tlic eylindiT
counterbore, as the illustration shows, to locati- the jig <-om'eiitrie
with the bore. As the holes in the cylinder are to be tapped or
threaded for studs, a “tap drill,” which is smaller in diameti-r
than the bolt body, is used and the drill is guitled bj- a renmv-
able bushing h 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 iirevents the jig
from turning with relation to the cylimU-r, when .Irilling the
other holes. When the jig is used for drilling the head, the
opposite side is placed
ne.xt to the work, us
shown at ( ’. 'I'his side
has a circular recess or
count erbore, which tits
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 guuh- bushing
of corresponding size are
used. 'I'he cyliiuler is, of
course, buretl and the
head turned before the drilling is done.

Jigs of the open class, as well us tho.se 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 iilaceil in the Jig.
When the work is quite large, the jig is frequently plucisi on it,
whereas small parts are naore often hekl in the jig, which is so
designed that the work can be clamjied in the proper jiosition.
The form of any jig depends, to a great extent, on the shaju* of
the work for which it is intended and also on the locatiiui of
the holes to be drilled. As the number t>f dilTerently .shaped
pieces which gd 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 J5 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





jig design

with ^ previous operatioii. After the w'ork is insi'iti'ti io the
jig, it is clamped by closing the cover C, which is hing<-(l at one
end and has a cam-shaped clamping latch /) at the other, that
engages a pin £ in the jig body. The four holes are tirilksi by
passing the drill through the guide bushings B in the cover.

Another jig of the same kind, but desigited for drilling a
hole having two diameters through the center of a steel hall,
is shown in Fig. 3. The work, which is shown enlargetl at A ,
is inserted while the cover is thrown back as indicateti liy the
dotted lines. The cover is then closed and tightened by the
cam-latA D, and the large part of the hole i.s drilled’ with
the jig in the position shown. The jig is then turned over and
a smaUer drill of the correct size is fed through guide hashing
B on the opposite side. The depth of the large hole c-ould he
gaged for each ball drilled, by feeding the drill spindle dow'n to
a cmain position as shown by graduation or other marks, hut
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, i, 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 t Limping hushing could
easily be changed.

The work is properly located by the inner ends ot the three
guide bushings ai, h, and c, and also by the hunting screws /
against which the casting is held by knurled thumb screws m
and n. When the holes a and b are being ilrilled, the jig is
placed with the cover side down, as shown at A in h'ig. 5, and
the drill is guided by removable bushings, om- of which is shown
at r. When the drilling is completed, the drill bushings are
replaced by reamer bushings and each hole is linished by ream-
ing. The small hole c, Fig. 4, is '» Hh* end of the cast-

ing by simply placing the jig on end as shown at H, hig. 5.
Box jigs which have to be placed in more than one position
for drilling the different holes are usuidly provided with feet
or extensions, as shown, which are accurately finished to align
the guide bushings properly with the drill. 'I'hese feet t‘xten<i
beyond any clamping screws, bolts, or bushings which may
protrude from the sides of the jigs, and provide- :i solid su])port.
When inserting work in a jig, care should bt- taken to remove
all chips which might have fallen upon tho.si- surfaces against
which the work is clamped and which iletermim- its location.

Still another jig of the box type, which is ijuite similar to
the one shown at A, Fig. 4, but is arranged dilTerently. owing
to the shape of the work and location of t lie hoh-s. is shown
at B in the same illustration. 'The work has tliree holes in
the base h, and a hole at i which is at tin angle of 5 degrees
with the base. The three holes arc drilled with the jig stand-
ing on the opposite end y, and the angular hole is drilled whili-
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 / 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 tin- flushing
0 and also by two locating screws p and a si<le locating screw q.
Adjustable screws / and h in the cover hold the casting down,
and it is held laterally by the two knurled thumb-si rews u
and V. If an attempt were made to tirill 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 difhcult 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 VH.

Details of Jig Design. — The general principles of the design
and use of jigs have been explained. The details of jig design
wiU 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 complete treatise covering dimensions and design is gi\a‘n in the
chapter on “Jig Bushings.”

In order to hold the work rigidly in (lie 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, (hat of preventing any
shiftin g 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 an; shown and ilescrilied
in the chapter on “Jig Clamping Devices."

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


JIG AND FIXTURE DESIGN


A TREATISE COVERING THE PRINCIPLES OF JIG AND FIXTURE DESIGN, THE IMPORTANT CONST'RUCTIONAL DETAILS, AND MANY DIFFERENT TYPES OF WORK-HOLDING DEVICES USED IN INTERCHANGEABLE MANUFACTURE


Edited by

FRANKLIN D. JONES




FIRST' EDITION


NEW YORK

THE INDUSTRIAL PRESS

London: the machinery PUBLISHING CO.










THE IMDUHTRIAL PEEHS
NEW YORK