Determining Machining Operation Type and Depth of Cuts for Multiple Cuts - Process Planning and Process Industrial Engineering

Lesson 69 of Industrial Engineering ONLINE Course.

Process Industrial Engineering FREE ONLINE Course (Module)

Production Process Planning - Sub-Module of Process Industrial Engineering

Lesson 70. Selecting Cutting Speed

Recommended Text: Process and Operation Planning by Gideon Halevi

Chapter 8. How to Determine the Type of Operation

https://books.google.co.in/books?id=tcHxCAAAQBAJ  - Preview

In this chapter method of determining depth of cut and feed are given. In the next chapter, determination of cutting speed is discussed.

1 Boundary Limit Strategy

Technical constraints are set as boundary limits, and then, bearing in mind economic considerations, working point within these limits are determined.

1.1 Technological constraints

Metal cutting theory indicates, minimum and maximum values for depth of cut, feed rate and cutting speed.

If the depth of cut is very less, the metal of the workpiece will only get compressed and will spring back when the took is passed and chip formation will not take place. Similarly, a low feed rate chip forming will not take place and only abrasive forming will take place. Similarly if feed is very high, tool wear process will become crater wear. The required tool wear is flank wear so that there is a definite tool life. Crater wear gives  sudden failure. Hence feed rate has to be within a limit for the tool to be within flank wear process.

Similarly in the case of cutting speed also, above a cutting speed, the resulting temperature creates diffusion wear in the tool. At low cutting temperature, the built up edge occurs and proper cutting will not take place.  Hence there are lower and higher limits to cutting speed.

Boundary value as per technological constraints

a(tmax)  = maximum depth of cut
a(tmin)  = minimum depth of cut

f(tmax)  = maximum feed
f(tmin) = minimum feed

v(tmax)  = maximum cutting speed
v(tmin) = minimum cutting speed

1.2 Part specification constraints

To meet specified surface roughness and tolerances, the feed rate and depth of cut have to be restricted to maximum values.

a(smax)  = maximum depth of cut  (surface finish specification provides the limits)
f(smax)  = maximum feed

1.3 Definition of material constraints

The work  material also has an effect on allowable maximum depth of cut and cutting speed.

a(hmax)  = maximum depth of cut  (h denotes hardness of the material, an important property)
v(hmax)  = cutting speed

1.4 Machine constraints

Vibrations are associated with chip formation and they affect surface finish. These vibrations reduce tool life also.

Experiments indicate that very low depth of cut and feed cause vibrations (chatter). 

Some authors state 0.06 mm as the lowest limit for depth of cut. 

Similarly, a feed rate value of 0.04 mm per revolution is specified as the minimum feed rate below which chatter occurs.

There is also a maximum depth of cut and cutting speed above which chatter occurs. The author recommends the following values

a(vmax)  = maximum depth of cut due to chatter (7 mm)
a(vmin)  = minimum depth of cut due to chatter (0.15mm)

f(vmin) = minimum feed rate due to chatter (0.04 mm/rev)
v(vmax) = maximum cutting speed due to chatter  - not specified

1.5 Definition of tool constraints

The tool material also gives boundary conditions to cutting parameters. At high feed rates, plastic deformation of the cutting edge takes place which is not desirable. 

Recommendation: Use a maximum value of feed rate between 0.5 mm per revolution to 0.8 mm per revolution for a cutting speed of 150 meters per minute. 

There are limits for depth of cut and cutting speed.

a(kmax)  = maximum depth of cut related to tool material
f(kmax)  = maximum feed related to tool material
v(kmax) = maximum cutting speed due to chatter related to tool material

1.6 User specified constraint

If user provides any limits based on his experience they have to be taken into account by process planners.

a(umax)  = maximum depth of cut indicated by user.
f(umax)  = maximum feed related indicated by user.
v(umax) = maximum cutting speed indicated by user.

1.7 Boundary limits summary

The above boundary value symbols are listed as per depth of cut, feed rate and cutting speed.

From the list of boundary values for a given situation, the minimum value is selected for maximum values, and the maximum value is selected for minimum values. These selected values are given the symbols.

a(amax)  a(amin)  f(amax)  f(amin) v(amax)  v(amin)     a indicates acceptable value for various cutting parameters.

2 Analysis of Cutting Conditions vs Part Specifications

The part specification gives the required tolerances and surface roughness. The part has to machined to conform to these specifications

2.1 Effect of cutting speed on surface roughness

A low cutting speeds BUE will occur and it scratches surface giving poor surface finish. As cutting speed increases above a limit, surface burns occur.

Halevi in 2003 book said, tool material and machine rigidity are being improved constantly, and hence recently declared values have to be ascertained and used. 

In the absence of specific values, Halevi suggested the values of 400 meters per minute as the upper limit and 60 meters per minute as the lower limit on steel parts with tool material being carbide.

2.2 Effect of feed rate on surface roughness

2.2.1 Turning processes

Halevi derived the formulas:

feed rate f mm/rev =  0.1Ra  for Ra <= 3.2    Ra is in micrometers
feed rate f mm/ rev = 0.18 Ra^0.5  for Ra>3.2

The above equations are used for finish cut and it is given the symbol f(smax) maximum feed rate based on surface finish criterion. For rough cuts f(amax) has to be used.  A table is provided for maximum feed rate and maximum depth as function of Ra and BHN. Refer Table 1.

2.2.2 Milling processes  (Not covered)

2.3 Effect of depth of cut on surface roughness

Maximum depth of cut limit based on surface roughness criterion

a(smax) = 32Ra/(BHN^0.8)

Example: Ra = 1.2 microns;  BHN  =  160

BHN^0.8 = 57.98

a(smax) =  32(1.2)/57.98 = .66 mm



3 Operational and Dependent Boundary Limits

As process planner makes decisions, these decision create limits for other variables.

3.1 Depth of cut as a function of feed rate

As the feed rate is determined, it puts a limit on the depth of cut. There will be a limit on the cutting force depending on the machine rigidity. The force is related to feed and depth as per the formula

Fx = (Cp)(a^u)(f^v)

Where Cp = specific cutting force (for medium steel  it is 220)
a = depth of cut and exponent u = 1.0
f = feed rate and exponent v = 0.75

3.2 Depth of cut as a function of a selected operation

In rough cut operation maximum depth of cut possible as per the boundary conditions is used and any remaining deviations from final specification have to be modified through finish cuts. The amount of material to be removed to correct deviations is given the symbol a(smin) and its value is added to a(amin) and the total has to be less than a(smax) which is the maximum depth of cut allowed for the finishing cut from the boundary limits.



4 The Algorithm for Selecting Cutting Operations

5 Example of Using the Algorithm

Current Tools

Iscar

10mm Max Depth, 4mm to 5mm Width, External Left Hand Indexable Grooving Toolholder

135mm OAL, 25mm x 25mm Shank, Uses GI.. Inserts, GHD Toolholder, Series Cut Grip

https://www.mscdirect.com/product/details/52713054

Update 29 Dec 2020

First 20 July 2020

PCB Design and Manufacturing Productivity - Product and Process Industrial Engineering

Printed Circuit Boards from 10,000 Feet – An Introduction for Electronics Beginners - Good information
Sam Sattel
https://www.autodesk.com/products/eagle/blog/printed-circuit-boards-10000-feet-introduction-electronics-beginners/

PCB Manufacturing Process Explanation

https://www.eurocircuits.com/making-a-pcb-pcb-manufacture-step-by-step/

https://www.pcbcart.com/article/content/PCB-manufacturing-process.html

Understanding PCB Manufacturing: Panelization
Nov 18, 2014
https://www.omnicircuitboards.com/blog/bid/357884/Understanding-PCB-Manufacturing-Panelization

Printed Circuit Board Manufacturing Technologies
https://www.thomasnet.com/articles/automation-electronics/PCB-manufacturing


https://www.electronics-notes.com/articles/constructional_techniques/printed-circuit-board-pcb/pcb-manufacturing-process.php

https://www.mclpcb.com/pcb-manufacturing-process/

PCB  Design and Manufacturing  Productivity Related News, Articles and Papers

2020

Tempo software for PCB Assembly

https://storage.pardot.com/618841/90717/All_About_Tempo_Video.mp4

2019


Cost vs. Price:The Economics of PCB Design
APRIL 9, 2019 KELLA KNACK

https://resources.altium.com/pcb-design-blog/cost-vs-price-the-economics-of-pcb-design

Clearance and Creepage Rules for PCB Assembly
Optimum Design Associates Blog
http://blog.optimumdesign.com/clearance-and-creepage-rules-for-pcb-assembly

Should Cost Examples For PCB Assembly
OPtimum rates are lower than China rates.
http://blog.optimumdesign.com/should-cost-examples-pcb-assembly

Effective. Efficient. Engineered Solutions
We Exceed Customer Expectations in Quality, Delivery and Service building long term relationships based on Customer Satisfaction Index.
End-End Program Management
Faster Time to Market
Reduced BoM Costs
Cost Effective Engineering
Putting Complex Product together
http://embedded360.com/

Test Engineering | Electronic Design Test Engineering
Test Engineering is one of the most important tasks in production. In this stage, all electronic boards are tested to verify that the product is free of any error. Testing usually has two stages: 1. The In-Circuit-Test (ICT) checks the components and the inter-connections of the parts on a PCB. With the ICT we can detect many problems, such as poor soldering, cold solder or solder bridge, improper component value, broken parts and similar connectivity problems.

Second stage of testing - the Functional Test. 2. The Functional Test is a complex test that is designed specifically for one particular product and will check the features and functionality of that product. By performing the functional test  the chance of an error is reduced to a minimum! We consider testability in our design right from the first day. Because of the experience and skills of our engineering staff, we are able to reduce the time spent in the test engineering section, especially with high quantity production. This is critical because each minute of delay in test engineering means a delay in getting the product out of the factory and to the client! As well, we can design test facilities on board, like test pads, connectors and test interfaces. Discuss your requirements to incorporate all of them into the final board layout.
https://arshon.com/test-engineering


Value Engineering of PCB Cloning

Value Engineering objective

A value engineering (VE) review of PCB Cloning candidates may reveal cost drivers over and beyond the sole source restrictions. Some probable high cost drivers are: excessive material requirements such as the capacitor, resistor, inductor and integrated circuits, PCB layout drawing defects, over design, functional redundancy, tolerance restrictions, excessive performance requirements, etc.
http://www.circuitwork.tech/value-engineering-of-pcb-cloning/

Allegro PCB DesignTrue DFM Technology
Real-time DFM checks ensure manufacturability

https://www.cadence.com/en_US/home/tools/pcb-design-and-analysis/pcb-layout/allegro-pcb-designer/allegro-pcb-designtrue-dfm-technology.html

Design for Manufacturability of Rigid Multi-Layer Boards

By: Tom Hausherr 

https://www.pcbcic.com/wp-content/uploads/2017/10/2-DFM_Guidelines_1.pdf

Knowledge based tool for conducting design

https://books.google.co.in/books?id=GjRBooewXJ0C&pg=PA568#v=onepage&q&f=true

https://www.tataelxsi.com/services/product-engineering-rd/hardware-design.html

2018



2017
mSAP: The New PCB Manufacturing Imperative for 5G Smartphones
October 23, 2017
https://www.orbotech.com/news-events/articles/msap-article


2016

Orbotech Releases Precise 800 Automated Optical Shaping 3D Solution for PCB Manufacturers
 May 22, 2016
The new technology should attract the attention of PCB manufacturers as it’s capable of removing excess copper as well as filling in the areas where it is missing. These features are significant as it means the ‘shaping solution’ is eliminating scrap and offering substantial savings on the bottom line with a rapid recoup regarding the initial investment.
https://3dprint.com/135037/orbotech-precise-800-aos/


The Biggest PCB Manufacturing Trends We’ve Seen This Year
AUGUST 18, 2016
https://resources.altium.com/pcb-design-blog/the-biggest-pcb-manufacturing-trends-we-ve-seen-this-year

What You Need To Know About PCB Design & Manufacturing
Jul 25, 2016
Interesting article with some references
https://medium.com/@darameja/what-you-need-to-know-about-pcb-design-manufacturing-1cb2885b77ba

PCBs Fabrication Methods
GUIDE: PCBs Fabrication Methods
https://technick.net/guides/electronics/pcb/


2015

Eight steps for efficient PCB manufacturing and assembly – Part One
By Michael Ford,   Posted: May 18, 2015
http://www.techdesignforums.com/practice/technique/pcb-manufacturing-eight-steps-part-one/




2014

2013

2012

Selecting PCB Materials for High-Frequency
Applications
By John Coonrod, Rogers Corporation, Advanced Circuit Materials Division
March/April 2012
Microwave Engineering europe

2011

2010

YouTube Video - PCB Design to Manufacture

https://www.youtube.com/watch?v=VXE_dh38HjU




1995


Horng-Hai Loh, Ming-Sing Lu, "Printed circuit board inspection using image analysis", Industrial Automation and Control: Emerging Technologies 1995. International IEEE/IAS Conference on, pp. 673-677, 1995.

Abstract:
This paper presents an inspection system for the defects on surface mounted device (SMD) printed circuit boards (PCBs). There are five types of defects, namely, missing component, misalignment, wrong orientation of IC chip, wrong parts and poor solder joints. Different algorithms are developed to detect these faults. Vision system has been introduced into almost every level of PCB manufacturing. They include PCB pattern inspection machines, SMD mounter with visual positioning, mounted SMD visual inspection machines, soldering inspection machines, assembled PCB visual inspection machines etc. Most of these vision systems achieve significant benefits.
https://ieeexplore.ieee.org/document/527640/

Manufacturing cost estimation for PCB assembly: An activity-based approach

N.S.Ong

International Journal of Production Economics

Volume 38, Issues 2–3, March 1995, Pages 159-172

https://www.sciencedirect.com/science/article/abs/pii/092552739400089S

1990

Vision systems for PCB manufacturing in Japan
S. Hata

Abstract: Current vision systems in Japanese printed circuit board (PCB) manufacturing lines are described. Vision systems have been introduced into almost every level of PCB manufacturing in Japan. They include mask pattern inspection machines, PCB pattern inspection machines, surface-mount device (SMD) mounters with visual positioning, mounted SMD visual inspection machines, soldering inspection machines, and assembled PCB visual inspection machines. Most of these vision systems were integrated successfully and achieved significant benefits.
Published in: [Proceedings] IECON '90: 16th Annual Conference of IEEE Industrial Electronics Society
Date of Conference: 27-30 Nov. 1990
https://ieeexplore.ieee.org/document/149241/


Updated on  4.12.2021,   27.12.2020,  5 December 2019, 22 August 2018

Search for PCB Cost Estimation

Selection of Metal Removal Processes - Initial Steps - Process Planning and Process Industrial Engineering

Lesson 67 of Industrial Engineering ONLINE Course.

Lesson 68. Fixturing and Clamping the Work Piece - Process Planning and Process Industrial Engineering

6. Forming by Metal Removal

https://books.google.co.in/books?id=tcHxCAAAQBAJ  - Preview

Basic Types of Material Removal Processes

The planner has the classify the shape as per part drawing to:

a. Round symmetrical
b. Prismatic

Above the basic shape there will be special features like holes, threads, slots, and flats.

Processes used for Round symmetrical parts: Turning, Grinding, Honing, Lapping, Polishing
Processes used for Prismatic parts: Milling, Grinding, Honing, Lapping, Polishing (Shaping, Planing)
Holes: Drilling, Boring, Reaming, Milling, Grinding, Broaching, 
Threads: Tapping, Thread Milling

Selection machining technology from the possible technology set is primarily dependent on surface finish.

Turning provides surface finish in the range of 0.8 microns to 25 microns Ra.
Grinding provides surface finish in the range of 0.1 microns to 1.6 microns Ra.

In the book by Gideon Halevi, Table 4 gives the surface roughness range of basic machining processes.

The actual value of the surface finish, from given range depends on factors like cutting speed, feed rate, too condition, and machine rigidity etc.

A basic process is selected first. In case of round symmetrical parts, turning is the basic process. If the basic process does not meet the surface roughness specification, an additional machining process is to be added, in addition to the first basic process. Then check the geometric tolerances (for parallelism, perpendicularity, concentricity and angularity). If the last machining process meets the required geometric tolerances the job can be completed. If it does not meet the specification, one more machining process has to be added.

When more than one machining process is used, part drawings have to be prepared for each one.  The working drawing or operation drawings are needed because the material to be left for the subsequent process has to be clearly indicated. Also the cutting parameters will be different for each operation.

Some guidelines in multiple operations;
1. In the first basic process you can specify the maximum capability value of the process as surface roughness.
2. In case of external dimension, increase the basic dimension  to 10 times of the equivalent tolerance possible with the  surface roughness specified above. (This modified dimension provides material for removal by the process.

http://www.cnctrainingcentre.com/cnc-turn/cnc-turning-surface-finish/

https://www.kennametal.com/in/en/resources/engineering-calculators/turning-calculators/surface-finish.html

https://www.meadinfo.org/2009/06/surface-finish-roughness-ra.html

Surface roughness/finish obtained in various machining operations from a machine design book
https://books.google.co.in/books?id=hKlfEB8tkcAC&pg=PA121#v=onepage&q&f=false



Machine Design
Jindal U. C.
Pearson Education India, 2010 - Electronic books - 892 pages

Machine Design is a text on the design of machine elements for the engineering undergraduates of mechanical/production/industrial disciplines. The book provides a comprehensive survey of machine elements and their analytical design methods. Besides explaining the fundamentals of the tools and techniques necessary to facilitate design calculations, the text includes extensive data on various aspects of machine elements, manufacturing considerations and materials.

https://books.google.co.in/books?id=hKlfEB8tkcAC


Gillespie L.K., (1988); Troubleshooting Manufacturing Processes,, SME, Dearborn, Michigan

Wierda, L.S., (1991); Linking Design, Process Planning and Cost Information by Feature Based Modeling, Journal of Engineering Design, Vol.2, No.1, pp.3-19.

Countersinking Handbook

LaRoux Gillespie

Industrial Press Inc., 2008 - Technology & Engineering - 353 pages

This unique handbook provides total coverage of issues related to countersinking and chamfering holes, including history of their use, design reasons, and basic cutter design. It features "how-to-use" details of the most used tools and techniques and complete information on the subject of countersinking holes of any size, including those over 10 inches in diameter. Its detailed approach to illustrating over 100 different tools designs is unparalleled in technical literature and is sure to be found useful by manufacturing engineers, shop foremen, and experienced users.

Provides discussions of all cutter material variations and options, feeds, speeds and coolants, tool holders, and applications--including plastics, metals, wood, composites, ceramics, glass, and dental materials.

Discusses side effects of countersinking, including stress risers.

Includes optimum applications for specific tool use, gaging countersinks, economics, pressworking countersinks, non-traditional countersinking methods, and references to standards and other published works.

Contains case histories, practical tips, and information to make process selection easier.

https://books.google.co.in/books?id=esWtCQuLWtIC

Updated on 27.12.2020
First published on 19.7.2020

Performance Evaluation of Computer Systems

 

https://nptel.ac.in/courses/106/106/106106048/

1. Raj Jain,"The Art of Computer Systems Performance Analysis: Techniques for Experimental Design, Measurement, Simulation, and Modeling", Wiley- Interscience, 1991. 

2. K.S. Trivedi,"Probability and Statistics with Reliability, Queueing and Computer Science Applications", John Wiley and Sons, 2001.

Modules / Lectures

Performance Evaluation of Computer Systems

Introduction to performance evaluation of computer systems

How to avoid common mistakes

Selection of techniques and metrics

Case study: Selection of techniques and metrics

Random Variables and probability distributions

Probability distributions-I

Probability distributions-II

Probability distributions-III

Stochastic process

Markov Chain

Slotted Aloha protocol model and discrete-time birth death process

Continuous time Markov chain and queuing theory-I

Queuing theory – I (Continued)

Queuing theory-II

Queuing theory-III

Queuing theory-IV

Queuing theory-V

Queuing theory-VI

Queuing networks-I

Queuing networks-II

Slotted Aloha Markov model

Simulations-I

Simulations-II

Simulations-III

Operational laws-I

Operational laws-II

Open and closed queuing networks

Approximate MVA

Convolution algorithm-I

Convolution algorithm-II

Load-dependent service centers

Hierarchical decomposition

Balanced Job Bounds

Confidence interval for propotions and introduction to experimental design

2k factorial design

2k r factorial design and 2k-p fractional factorial design

Programming aspects of discrete-event simulations-I

Programming aspects of discrete-event simulations-II

Discrete-event simulations-III

PetriNets-I

PetriNets-II

PetriNets-III

Assembly Automation and Product Design - Boothroyd - Book Information and Related Information

 

Industrial Engineering - Role of Engineering, Mechanization and Automation

In process improvement study or projects, to do a task in the most productive manner, the most efficient manual method (best manual method), best mechanized method and best automation method are to be compared and the most productive method has to be employed. This comparison has to be done at element or suboperation level.

Source: Book: Motion and Time Study: Design and Measurement of Work, Ralph M. Barnes, 7th Edition, Chapter 18. Motion Study, Mechanization, and Automation.

Jidoka - Automation and Mechanization - Process Engineering and Industrial Engineering in Toyota Production System

Jidoka, a pillar of Toyota Production Systems advocates automation with human touch in all operations of a process to increase productivity of operators as well as that of total systems.

https://nraoiekc.blogspot.com/2021/04/jidoka-automation-and-mechanization.html

Assembly Automation and Product Design - Table of Contents

INTRODUCTION

Historical Development of the Assembly Process

Choice of Assembly Method

Social Effects of Automation

References

AUTOMATIC ASSEMBLY TRANSFER SYSTEMS

Continuous Transfer

Intermittent Transfer

Indexing Mechanisms

Operator-Paced Free-Transfer Machine

References

AUTOMATIC FEEDING AND ORIENTING - VIBRATORY FEEDERS

Mechanics of Vibratory Conveying

Effect of Frequency

Effect of Track Acceleration

Effect of Vibration Angle

Effect of Track Angle

Effect of Coefficient of Friction

Estimating the Mean Conveying Velocity

Load Sensitivity

Solutions to Load Sensitivity

Spiral Elevators

Balanced Feeders

Orientation of Parts

Typical Orienting System

Effect of Active Orienting Devices on Feed Rate

Analysis of Orienting Systems

Performance of an Orienting Device

Natural Resting Aspects of Parts for Automatic Handling

Analysis of a Typical Orienting System

Out-of-Bowl Tooling

References

AUTOMATIC FEEDING AND ORIENTING - MECHANICAL FEEDERS

Reciprocating-Tube Hopper Feeder

Centerboard Hopper Feeder

Reciprocating-Fork Hopper Feeder

External Gate Hopper Feeder

Rotary-Disk Feeder

Centrifugal Hopper Feeder

Stationary-Hook Hopper Feeder

Bladed-Wheel Hopper Feeder

Tumbling-Barrel Hopper Feeder

Rotary-Centerboard Hopper Feeder

Magnetic-Disk Feeder

Elevating Hopper Feeder

Magnetic Elevating Hopper Feeder

Magazines

References

FEED TRACKS, ESCAPEMENTS, PARTS-PLACEMENT MECHANISMS, AND ROBOTS

Gravity Feed Tracks

Powered Feed Tracks

Escapements

Parts-Placing Mechanisms

Assembly Robots

References

PERFORMANCE AND ECONOMICS OF ASSEMBLY SYSTEMS

Indexing Machines

Free-Transfer Machines

Basis for Economic Comparisons of Automation Equipment

Comparison of Indexing and Free-Transfer Machines

Economics of Robot Assembly

References

DESIGN FOR MANUAL ASSEMBLY

Introduction

Where Design for Assembly Fits in the Design Process

General Design Guidelines for Manual Assembly

Development of a Systematic DFA Analysis Method

DFA Index

Classification System for Manual Handling

Classification System for Manual Insertion and Fastening

Effect of Part Symmetry on Handling Time

Effect of Part Thickness and Size on Handling Time

Effect of Weight on Handling Time

Parts Requiring Two Hands for Manipulation

Effects of Combinations of Factors

Threaded Fasteners

Effects of Holding Down

Problems with Manual Assembly Time Standards

Application of the DFA Method

Further General Design Guidelines

References

PRODUCT DESIGN FOR HIGH-SPEED AUTOMATIC ASSEMBLY AND ROBOT ASSEMBLY

Introduction

Design of Parts for High-Speed Feeding and Orienting

Example

Additional Feeding Difficulties

High-Speed Automatic Insertion

Example

Analysis of an Assembly

General Rules for Product Design for Automation

Design of Parts for Feeding and Orienting

Summary of Design Rules for High-Speed Automatic Assembly

Product Design for Robot Assembly

References

PRINTED-CIRCUIT-BOARD ASSEMBLY

Introduction

Terminology

Assembly Process for PCBs

SMD Technology

Estimation of PCB Assembly Costs

Worksheet and Database for PCB Assembly Cost Analysis

PCB Assembly - Equations and Data for Total Operation Cost

Glossary of Terms

References

FEASIBILITY STUDY FOR ASSEMBLY AUTOMATION

Machine Design Factors to Reduce Machine Downtime

Due to Defective Parts

Feasibility Study

References

Problems

Appendix A: Simple Method for the Determination of the Coefficient of Dynamic Friction

The Method

Analysis

Precision of the Method

Discussion

Reference

Appendix B: Out-of-Phase Vibratory Conveyors

Out-of-Phase Conveying

Practical Applications

Reference

Appendix C: Laboratory Experiments

Performance of a Vibratory-Bowl Feeder

Performance of a Horizontal-Delivery Gravity Feed Track

Conclusions

Appendix D: Feeding and Orienting Techniques for Small Parts

Coding System

Feeding and Orienting Techniques

Orienting Devices for Vibratory-Bowl Feeders

Nonvibratory Feeders

Nomenclature

Assembly Automation - Introduction, Books and Articles

Automation of Operations in Flow Process Chart

Automated Manufacturing - Production Operations in Manufacturing Processes

Automated Inspection - Bibliography

Automated Material Handling - Transport - Bibliography 

Automated Storage and Warehousing - Storage Operation Improvement in Engineering Processes

Automation for Preventing Temporary Delays - Lean WIP Processes - Systems

Jidoka - Automation and Mechanization - Process Engineering and Industrial Engineering in Toyota Production System

Jidoka, a pillar of Toyota Production Systems advocates automation with human touch in all operations of a process to increase productivity of operators as well as that of total systems.

https://nraoiekc.blogspot.com/2021/04/jidoka-automation-and-mechanization.html

 5 Principles of Flexible Assembly Line Design

By following these principles of flexible assembly line design, manufacturers can pursue lean manufacturing in their current operation while also building capabilities to maintain or add lean improvements in the future.

Mark Sobkow, Jul 9th, 2018

https://www.automationworld.com/home/blog/13318850/5-principles-of-flexible-assembly-line-design

Issues in Designing and Building Automated Assembly Systems

September 10, 2018

John Sprovieri

https://www.assemblymag.com/articles/94475-designing-and-building-automated-assembly-systems

https://www.intechopen.com/books/factory-automation

https://www.intechopen.com/books/new-trends-in-industrial-automation

 2nd Edition,  2005

Assembly Automation and Product Design

By Geoffrey Boothroyd

https://www.routledge.com/Assembly-Automation-and-Product-Design/Boothroyd/p/book/9781574446432

Assembly Automation and Product Design

Geoffrey Boothroyd

CRC Press, 30-Aug-1991 - Technology & Engineering - 432 pages

https://books.google.co.in/books/about/Assembly_Automation_and_Product_Design.html?id=XFtgaNFzMHQC

Assembly Automation, Second Edition

A Management Handbook

Frank J. Riley

Pages 320 Pages, Hardcover

Published Date: June, 2005

https://books.industrialpress.com/assembly-automation-second-edition.html

1st Edition

Assembly Processes

Finishing, Packaging, and Automation

Edited By Richard Crowson

Copyright Year 2006

https://www.routledge.com/Assembly-Processes-Finishing-Packaging-and-Automation/Crowson/p/book/9780849355653

Assembly system configuration through Industry 4.0 principles: the expected change in the actual paradigms

YuvalCohen* MaurizioFaccio** Francesco Gabriele Galizia** CristinaMora*** FrancescoPilati***

IFAC-PapersOnLine

Volume 50, Issue 1, July 2017, Pages 14958-14963

https://www.sciencedirect.com/science/article/pii/S2405896317334754

Design for automation in manufacturing systems and processes

2016 MIT MBA Thesis

Ezolino, Juan Stefano

https://dspace.mit.edu/handle/1721.1/104311

Automation in Mechanical Systems 

Modules / Lectures

Introduction

Automated systems

Hydraulic and pneumatic controls

Electropenumatics

Programmable logic controllers

https://nptel.ac.in/courses/112/102/112102011/

Lean Automation

February 1, 2009

By Patrick Waurzyniak

Contributing Editor,

SME Media

Combining lean manufacturing tools with the right automation systems can boost productivity

https://www.sme.org/technologies/articles/2009/lean-automation/

Hyundai WIA Assembly automation line

Hyundai WIA provides automation lines to assemble key components of finished car, engine and transmission.

https://machine.hyundai-wia.com/eu/fa/assembly.asp

Rockwell Automation

Design flexible manufacturing and assembly machines with the right balance of machine performance, safety, and cost.

Flexibility and Speed

Increase Flexibility, Decrease Machine Time and Cost

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F.W. Taylor - Developing and Employing First Class People in an Organization

 

The aim in each establishment should be:

(a) That each workman should be given as far as possible the highest grade of work for which his ability and physique fit him.

(b) That each workman should be given a task that calls upon to turn out the maximum amount of work which a first-rate man of his class can do and thrive.

(c) That each workman, when he works at the best pace of a first-class man, should be paid from 30 per cent to 100 per cent according to the nature of the work which he does, beyond the average of his class.

And this means high wages and a low labor cost. 

These conditions not only serve the best interests of the employer, but they tend to raise each workman to the highest level which he is fitted to attain by making him use his best faculties, forcing him to become and remain ambitious and energetic, and giving him sufficient pay to live better than in the past.

Under these conditions the writer has seen many first-class men developed who otherwise would have remained second or third class all of their lives. (First class, second class and third class are terminology of Taylor's period.)

Is not the presence or absence of these conditions the best indication that any system of management is either well or badly applied? And in considering the relative merits of different types of management, is not that system the best which will establish these conditions with the greatest certainty, precision, and speed?

In comparing the management of manufacturing and engineering companies by this standard, it is surprising to see how far they fall short. In very few of those which are best organized, any person has  attained even approximately the maximum output of first-class men achieved by many in organizations that have adopted scientific management.

Source
F.W. Taylor, Shop Management - With Appropriate Sections
http://nraoiekc.blogspot.com/2016/03/fw-taylor-shop-management-with.html

Productivity Science of Human Effort - Development of Science in Mechanic Arts

INDUSTRIAL ENGINEERING is redesign (engineering) of Products, Facilities and Processes for Productivity increase.
Productivity Management Imperative for USA - McKinsey. Returning US productivity to its long-term trend of 2.2 percent annual growth would add $10 trillion in cumulative GDP over the next ten years (2023 - 2030).

INTRODUCTION TO MODERN INDUSTRIAL ENGINEERING. E-Book FREE Download. 

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Lesson 4

 Industrial Engineering ONLINE Course - Main Page

Development of Science in Mechanic Arts  =  Productivity science of human effort

From: F.W. Taylor, Scientific Management, All Chapters
F.W. Taylor Scientific Management - With Appropriate Sections

                                                                 Source: Wikipedia 

The Science of Human Motions

The science which exists in most of the mechanic arts is, however, far simpler than the science of cutting metals. In almost all cases, in fact, the laws or rules which are developed are so simple that the average man would hardly dignify them with the name of a science. In most trades, the science is developed through a recording of movements made by mechanics, and the time taken to do those movement using time study and a simple analysis of the recorded data. It is termed time study of the movements required by the workmen to do some small part of his work, and this study is usually made by a man equipped merely with a stop-watch and recording sheet.  Hundreds of these "time-study men" are now engaged in developing elementary scientific knowledge where before existed only rule of thumb. The motion study of Mr. Gilbreth in bricklaying is a much more elaborate investigation and many activities of mechanics do not require that elaborate effort to develop science.  

The general steps to be taken in developing simples law of many  elemental activities of mechanics are  as follows:

First. Find, say, 10 or 15 different men (preferably in as many separate establishments and different parts of the country) who are especially skillful in doing the particular work to be analyzed.

Second. Study the exact series of elementary operations or motions which each of these men uses in doing the work which is being investigated, as well as the implements each man uses.

Third. Study with a stop-watch the time required to make each of these elementary movements and then select the quickest way of doing each element of the work.

Fourth. Eliminate all false movements, slow movements, and useless movements.

Fifth. After doing away with all unnecessary movements, collect into one series the quickest and best movements as well as the best implements.

This one new method, involving that series of motions which can be made quickest and best, is then substituted in place of the ten or fifteen inferior series which were formerly in use. This best method becomes standard, and remains standard, to be taught first to the teachers (or functional foremen) and by them to every workman in the establishment until it is superseded by a quicker and better series of movements. In this simple way one element after another of the science is developed. As we can see, it is simple because we are not going the causal factors. We are only trying to identify the way of working that is giving the minimum time presently.

In the same way each type of implement used in a trade is studied. Under the philosophy of the management of "initiative and incentive" each work-man is called upon to use his own best judgment, so as to do the work in the quickest time, and from this results in all cases a large variety in the shapes and types of implements which are used for any specific purpose. Scientific management requires, first, a careful investigation of each of the many modifications of the same implement, developed under rule of thumb; and second, after a time study has been made of the speed attainable with each of these implements, that the good points of several of them shall be united in a single standard implement, which will enable the workman to work faster and with greater ease than he could before. This one implement, then, is adopted as standard in place of the many different kinds before in use, and it remains standard for all workmen to use until superseded by an implement which has been shown, through motion and time study, to be still better.

With this explanation it will be seen that the development of a simple science of productivity to replace rule of thumb is in most cases by no means a formidable undertaking, and that it can be accomplished by ordinary, every-day men without any elaborate scientific training; but that, on the other hand, the successful use of even the simplest improvement of this kind calls for records, system, and cooperation where in the past existed only individual effort.

Notes by Narayana Rao

1. "With this explanation it will be seen that the development of a science to replace rule of thumb is in most cases by no means a formidable undertaking, and that it can be accomplished by ordinary, every-day men without any elaborate scientific training."

Taylor expressed the opinion that identifying the operator who is doing the job quickest and further improving the method by identifying waste motions and motions not required does not require persons with indepth training in science and engineering. It can be done by persons with lesser education. 

2. "Even the motion study of Mr. Gilbreth in bricklaying (described on pages 77 to 84) involves a much more elaborate investigation than that which occurs in most cases."

Taylor considers motion study advocated by Frank Gilbreth to be a more elaborate investigation than his recommendation.

3. "This one implement, then, is adopted as standard in place of the many different kinds before in use, and it remains standard for all workmen to use until superseded by an implement which has been shown, through motion and time study, to be still better."

Taylor coined the term "motion and time study" in 1911 itself.

4. "The science which exists in most of the mechanic arts is, however, far simpler than the science of cutting metals."

For science of machine, you require engineers with interest in development of science - productivity science of machines as well as science of machine work.

Science of Motives of Men - F.W. Taylor

Accurate Study of the Motives Which Influence Men. 

There is another type of scientific investigation which has been referred to several times in this paper, and which should receive special attention, namely, the accurate study of the motives which influence men. At first it may appear that this is a matter for individual observation and judgment, and is not a proper subject for exact scientific experiments. It is true that the laws which result from experiments of this class, owing to the fact that the very complex organism--the human being--is being experimented with, are subject to a larger number of exceptions than is the case with laws relating to material things. And yet laws of this kind, which apply to a large majority of men, unquestionably exist, and when clearly defined are of great value as a guide in dealing with men. In developing these laws, accurate, carefully planned and executed experiments, extending through a term of years, have been made, similar in a general way to the experiments upon various other elements which have been referred to in this paper. Perhaps the most important law belonging to this class, in its relation to scientific management, is the effect which the task idea has upon the efficiency of the workman. This, in fact, has become such an important element of the mechanism of scientific management, that by a great number of people scientific management has come to be known as "task management."

There is absolutely nothing new in the task idea. Each one of us will remember that in his own case this idea was applied with good results in his school-boy days. No efficient teacher would think of giving a class of students an indefinite lesson to learn. Each day a definite, clear-cut task is set by the teacher before each scholar, stating that he must learn just so much of the subject; and it is only by this means that proper, systematic progress can be made by the students. The average boy would go very slowly if, instead of being given a task, he were told to do as much as he could. All of us are grown-up children, and it is equally true that the average workman will work with the greatest satisfaction, both to himself and to his employer, when he is given each day a definite task which he is to perform in a given time, and which constitutes a proper day's work for a good workman. This

furnishes the workman with a clear-cut standard, by which he can throughout the day measure his own progress, and the accomplishment of which affords him the greatest satisfaction.

The writer has described in other papers a series of experiments made upon workmen, which have resulted in demonstrating the fact that it is impossible, through any long period of time, to get work-men to work much harder than the average men around them, unless they are assured a large and a permanent increase in their pay. This series of experiments, however, also proved that plenty of workmen can be found who are willing to work at their best speed, provided they are given this liberal increase in wages. The workman must, however, be fully assured that this increase beyond the average is to be permanent. Our experiments have shown that the exact percentage of increase required to make a workman work at his highest speed depends upon the kind of work which the man is doing.

It is absolutely necessary, then, when workmen are daily given a task which calls for a high rate of speed on their part, that they should also be insured the necessary high rate of pay whenever they are

successful. This involves not only fixing for each man his daily task, but also paying him a large bonus, or premium, each time that he succeeds in doing his task in the given time. It is difficult to

appreciate in full measure the help which the proper use of these two elements is to the workman in elevating him to the highest standard of efficiency and speed in his trade, and then keeping him there, unless one has seen first the old plan and afterward the new tried upon the same man. And in fact until one has seen similar accurate experiments made upon various grades of workmen engaged in doing widely different types of work. The remarkable and almost uniformly good results from the correct application of the task and the bonus must be seen to be appreciated.

These two elements, the task and the bonus (which, as has been pointed out in previous papers, can be applied in several ways), constitute two of the most important elements of the mechanism of scientific management. They are especially important from the fact that they are, as it were, a climax, demanding before they can be used almost all of the other elements of the mechanism; such as a planning department, accurate time study, standardization of methods and implements, a routing system, the training of functional foremen or teachers, and in many cases instruction cards slide-rules, etc. (Referred to  in  more detail on page 129?.)

The necessity for systematically teaching workmen how to work to the best advantage has been several times referred to. It seems desirable, therefore, to explain in rather more detail how this teaching is done. In the case of a machine-shop which is managed under the modern system, detailed written instructions as to the best way of doing each piece of work are prepared in advance, by men in the planning department. These instructions represent the combined work of several men in the planning room, each of whom has his own specialty, or function. One of them, for instance, is a specialist on the proper speeds and cutting tools to be used. He uses the slide-rules which have been above described as an aid, to guide him in obtaining proper speeds, etc. Another man analyzes the best and quickest motions to be made by the workman in setting the work up in the machine and removing it, etc. Still a third, through the time-study records which have been accumulated, makes out a timetable giving the proper speed for doing each element of the work. The directions of all of these men, however, are written on a single instruction card, or sheet.

These men of necessity spend most of their time in the planning department, because they must be close to the records and data which they continually use in their work, and because this work requires the use of a desk and freedom from interruption. Human nature is such, however, that many of the workmen, if left to themselves, would pay but little attention to their written instructions. It is necessary, therefore, to provide teachers (called functional foremen) to see that the workmen both understand and carry out these written instructions.

Under functional management, the old-fashioned single foreman is superseded by eight different men, each one of whom has his own special duties, and these men, acting as the agents for the planning department (see paragraph 234 to 245 of the paper entitled "Shop Management"), are the expert teachers, who are at all times in the shop, helping, and directing the workmen. Being each one chosen for his knowledge and personal skill in his specialty, they are able not only to tell the

workman what he should do, but in case of necessity they do the work themselves in the presence of the workman, so as to show him not only the best but also the quickest methods.

One of these teachers (called the inspector) sees to it that he understands the drawings and instructions for doing the work. He teaches him how to do work of the right quality; how to make it fine and exact where it should be fine, and rough and quick where accuracy is not required,--the one being just as important for success as the other. The second teacher (the gang boss) shows him how to set up the job in his machine, and teaches him to make all of his personal motions in the quickest and best way. The third (the speed boss) sees that the machine is run at the best speed and that the proper tool is used in the particular way which will enable the machine to finish its product in the shortest possible time. In addition to the assistance given by these teachers, the workman receives orders and help from four other men; from the "repair boss" as to the adjustment, cleanliness, and general care of his machine, belting, etc.; from the "time clerk," as to everything relating to his pay and to proper written reports and returns; from the "route clerk," as to the order in which he does his work and as to the movement of the work from one part of the shop to another; and, in case a workman gets into any trouble with any of his various bosses, the "disciplinarian" interviews him.

It must be understood, of course, that all workmen engaged on the same kind of work do not require the same amount of individual teaching and attention from the functional foremen. The men who are new at a given operation naturally require far more teaching and watching than those who have been a long time at the same kind of jobs.

Now, when through all of this teaching and this minute instruction the work is apparently made so smooth and easy for the workman, the first impression is that this all tends to make him a mere automaton, a wooden man. As the workmen frequently say when they first come under this system, "Why, I am not allowed to think or move without some one interfering or doing it for me!" The same criticism and objection, however, can be raised against all other modern subdivision of labor. It does not follow, for example, that the modern surgeon is any more narrow or wooden a man than the early settler of this country. The frontiersman, however, had to be not only a surgeon, but also an

architect, house-builder, lumberman, farmer, soldier, and doctor, and he had to settle his law cases with a gun. You would hardly say that the life of the modern surgeon is any more narrowing, or that he is more of a wooden man than the frontiersman. The many problems to be met and solved by the surgeon are just as intricate and difficult and as developing and broadening in their way as were those of the frontiersman.

And it should be remembered that the training of the surgeon has been almost identical in type with the teaching and training which is given to the workman under scientific management. The surgeon, all through his early years, is under the closest supervision of more experienced men, who show him in the minutest way how each element of his work is best done. They provide him with the finest implements, each one of which has been the subject of special study and development, and then insist upon his using each of these implements in the very best way. All of this teaching, however, in no way narrows him. On the contrary he is quickly given the very best knowledge of his predecessors; and, provided (as he is, right from the start) with standard implements and methods which represent the best knowledge of the world up to date, he is able to use his own originality and ingenuity to make real additions to the world's knowledge, instead of reinventing things which are old. In a similar way the workman who is cooperating with his many teachers under scientific management has an opportunity to develop which is at least as good as and generally better than that which he had when the whole problem was "up to him" and he did his work entirely unaided.

If it were true that the workman would develop into a larger and finer man without all of this teaching, and without the help of the laws which have been formulated for doing his particular job, then it would follow that the young man who now comes to college to have the help of a teacher in mathematics, physics, chemistry, Latin, Greek, etc., would do better to study these things unaided and by himself. The only difference in the two cases is that students come to their teachers, while from the nature of the work done by the mechanic under scientific management, the teachers must go to him. What really happens is that, with the aid of the science which is invariably developed, and through the instructions from his teachers, each workman of a given intellectual capacity is enabled to do a much higher, more interesting, and finally more developing and more profitable kind of work than he was before able to do. The laborer who before was unable to do anything beyond, perhaps, shoveling and wheeling dirt from place to place, or carrying the work from one part of the shop to another, is in many cases taught to do the more elementary machinist's work, accompanied by the agreeable surroundings and the interesting variety and higher wages which go with the machinist's trade. The cheap machinist or helper, who before was able to run perhaps merely a drill press, is taught to do the more intricate and higher priced lathe and planer work, while the highly skilled and more intelligent machinists become functional foremen and teachers. And so on, right up the line.

Encourage Workmen to Suggest Improvements in Methods and Implements

It may seem that with scientific management there is not the same incentive for the workman to use his ingenuity in devising new and better methods of doing the work, as well as in improving his implements, that there is with the old type of management. It is true that with scientific management the workman is not allowed to use whatever implements and methods he sees fit in the daily practice of his work. Every encouragement, however, should be given him to suggest improvements, both in methods and in implements. And whenever a workman proposes an improvement, it should be the policy of the management to make a careful analysis of the new method, and if necessary conduct a series of experiments to determine accurately the relative merit of the new suggestion and of the old standard. And whenever the new method is found to be markedly superior to the old, it should be adopted as the standard for the whole establishment. The workman should be given the full credit for the improvement, and should be paid a cash premium as a reward for his ingenuity. In this way the true initiative of the workmen is better attained under scientific management than under the old

individual plan.

F.W. Taylor, Scientific Management

All Chapters
F.W. Taylor Scientific Management - With Appropriate Sections

Next Chapter
Scientific Management in Its Essence - F.W. Taylor

Updated 9 July 2016,  4 August 2013

F.W. Taylor - Bicycle Balls Inspection - Process Human Effort Industrial Engineering

INDUSTRIAL ENGINEERING is redesign (engineering) of Products, Facilities and Processes for Productivity increase.
Productivity Management Imperative for USA - McKinsey. Returning US productivity to its long-term trend of 2.2 percent annual growth would add $10 trillion in cumulative GDP over the next ten years (2023 - 2030).

INTRODUCTION TO MODERN INDUSTRIAL ENGINEERING. E-Book FREE Download. 

https://academia.edu/103626052/INTRODUCTION_TO_MODERN_INDUSTRIAL_ENGINEERING_Version_3_0

Lesson 3. Process Human Effort Industrial Engineering

Abridged version of

 Illustrations of Success of Scientific Management - Bricklaying Improvement by Gilbreth

From Scientific Management All Chapters
F.W. Taylor Scientific Management - With Appropriate Sections

Scientific selection of the workman 

In most cases (particularly when the work to be done is intricate in its nature) the "development of the science" is the most important of the four great elements of the new management. There are instances, however, in which the "scientific selection of the workman" counts for more than anything else.

A case of this type is well illustrated in the work of inspecting bicycle balls.

When the bicycle craze was at its height some years ago several million small balls made of hardened steel were used annually in bicycle bearings. And among the twenty or more operations used in making steel balls, perhaps the most important was that of inspecting them after final polishing so as to remove all fire-cracked or otherwise imperfect balls before boxing.

The writer was given the task of systematizing the largest bicycle ball factory in this country. This company had been running for from eight to ten years on ordinary day work before he undertook its reorganization, so that the one hundred and twenty or more girls who were inspecting the balls were "old hands" and skilled at their jobs.

Independent Way of Working to Scientific Cooperation Based Work

It is impossible even in the most elementary work to change rapidly from the old independence of individual day work to scientific cooperation.

In most cases, however, there exist certain imperfections in working conditions which can at once be improved with benefit to all concerned.

In this instance it was found that the inspectors (girls) were working ten and one-half hours per day (with a Saturday half holiday.)

Their work consisted briefly in placing a row of small polished steel balls on the back of the left hand, in the crease between two of the fingers pressed together, and while they were rolled over and over, they were minutely examined in a strong light, and with the aid of a magnet held in the right hand, the defective balls were picked out and thrown into especial boxes. Four kinds of defects were looked for-dented, soft, scratched, and fire-cracked--and they were mostly so minute as to be invisible to an eye not especially trained to this work. It required the closest attention and concentration, so that the nervous tension of the inspectors was considerable, in spite of the fact that they were comfortably seated and were not physically tired.

A most casual study made it evident that a very considerable part of the ten and one-half hours during which the girls were supposed to work was really spent in idleness because the working period was too long. It is a matter of ordinary common sense to plan working hours so that the workers can really "work while they work" and "play while they play," and not mix the two.

Before the arrival of Mr. Sanford E. Thompson, who undertook a scientific study of the whole process, we decided, therefore, to shorten the working hours.

The old foreman who had been over the inspecting room for years was instructed to interview one after another of the better inspectors and the more influential girls and persuade them that they could do just as much work in ten hours each day as they had been doing in ten and one-half hours. Each girl was told that the proposition was to shorten the day's work to ten hours and pay them the same day's pay they were receiving for the ten and one-half hours.

In about two weeks the foreman reported that all of the girls he had talked to agreed that they could do their present work just as well in ten hours as in ten and one-half and that they approved of the change.

The writer had not been especially noted for his tact so he decided that it would be wise for him to display a little more of this quality by having the girls vote on the new proposition. This decision was hardly justified, however, for when the vote was taken the girls were unanimous that 10 1/2 hours was good enough for them and they wanted no innovation of any kind.

This settled the matter for the time being. A few months later tact was thrown to the winds and the working hours were arbitrarily shortened in successive steps to 10 hours, 9 1/2, 9, and 8 1/2 (the pay per day remaining the same); and with each shortening of the working day the output increased instead of diminishing.

The change from the old to the scientific method in this department was made under the direction of Mr. Sanford E. Thompson, perhaps the most experienced man in motion and time study in this country, under the general superintendence of Mr. H. L. Gantt.

In the Physiological departments of our universities experiments are regularly conducted to determine what is known as the "personal coefficient" of the man tested. This is done by suddenly bringing some object, the letter A or B for instance, within the range of vision of the subject, who, the instant he recognizes the letter has to do some definite thing, such as to press a particular electric button. The time which elapses from the instant the letter comes in view until the subject presses the button is accurately recorded by a delicate scientific instrument.

This test shows conclusively that there is a great difference in the "personal coefficient" of different men. Some individuals are born with unusually quick powers of perception accompanied by quick responsive action. With some the message is almost instantly transmitted from the eye to the brain, and the brain equally quickly responds by sending the proper message to the hand.

Men of this type are said to have a low "personal coefficient," while those of slow perception and slow action have a high "personal coefficient."

Mr. Thompson soon recognized that the quality most needed for bicycle ball inspectors was a low personal coefficient. Of course the ordinary qualities of endurance and industry were also called for. The girls with  a low "personal coefficient" were selected for productivity improvement training. 

While the gradual selection of girls was going on other changes were also being made.

Guarding Against Deterioration of Quality Due to Increase in Output

One of the dangers to be guarded against, when the pay of the man or woman is made in any way to depend on the quantity of the work done, is that in the effort to increase the quantity the quality is apt to deteriorate.

It is necessary in almost all cases, therefore, to take definite steps to insure against any falling off in quality before moving in any way towards an increase in quantity.

It is important for industrial engineers to note the above point. Industrial engineering right from the initial Taylor days, gave special attention to maintain the quality in productivity improvement modifications of the process.

In the work of these particular girls quality was the very essence. They were engaged in picking out all defective balls.

The first step, therefore, was to make it impossible for them to slight their work without being, found out. This was accomplished through what is known as over-inspection. Each one of four of the most trust-worthy girls was given each day a lot of balls to inspect which had been examined the day before by one of the regular inspectors; the number identifying the lot to be over-inspected having been changed by the foreman so that none of the over-inspectors knew whose work they were examining. In addition to this one of the lots inspected by the four over-inspectors was examined on the following day by the chief inspector, selected on account of her especial accuracy and integrity.

An effective expedient was adopted for checking the honesty and accuracy of the over-inspection. Every two or three days a lot of balls was especially prepared by the foreman, who counted out a definite number of perfect balls, and added a recorded number of defective balls of each kind. Neither the inspectors nor the over-inspectors had any means of distinguishing this prepared lot from the regular commercial lots. Thus the quality of the process was continuously monitored.

More Measures to Improve Productivity

After insuring in this way against deterioration in quality, effective means were at once adopted to increase the output. Improved day work was substituted for the old slipshod method. An accurate daily record was kept both as to the quantity and quality of the work done in order to guard against any personal prejudice on the part of the foreman and to insure absolute impartiality and justice for each inspector. In a comparatively short time this record enabled the foreman to stir the ambition of all the inspectors by increasing the wages of those who turned out a large quantity and good quality, while at the same time lowering the pay of those who did indifferent work and discharging others who proved to be incorrigibly slow or careless. A careful examination was then made of the way in which each girl spent her time and an accurate time study was undertaken, through the use of a stop-watch and record blanks, to determine how fast each kind of inspection should be done, and to establish the exact conditions under which each girl could do her quickest and best work, while at the same time guarding against giving her a task so severe that there was danger from over fatigue or exhaustion. This investigation showed that the girls spent a considerable part of their time either in partial idleness, talking and half working, or in actually doing nothing.

Even when the hours of labor had been shortened from 10 1/2 to 8 1/2 hours a close observation of the girls showed that after about an hour and one-half of consecutive work they began to get nervous (fatigued). They evidently needed a rest. It is wise to stop short of the point at which overstrain begins, so we arranged for them to have a ten minutes period for recreation at the end of each hour and one quarter. During these recess periods (two of ten minutes each in the morning and two in the afternoon) they were obliged to stop work and were encouraged to leave their seats and get a complete change of occupation by walking around and talking, etc.

Shortening their hours of labor, however, and providing so far as we new the most favorable working conditions made it possible for them to really work steadily. 

And it is only after this stage in the reorganization is reached, when the girls have been properly selected and on the one hand such precautions have been taken as to guard against the possibility of over-driving them, while,  the most favorable working conditions have been established, that the final step should be taken which insures them what they most want, namely, high wages, and the employers what they most want, namely, the maximum output and best quality of work, -which means a low labor cost.

This step is to give each girl each day a carefully measured task which demands a full day's work from a competent operative, and also to give her a large premium or bonus whenever she accomplishes this task.

This was done in this case through establishing what is known as differential rate piece work.*

Under this system the pay of each girl was increased in proportion to the quantity of her output and also still more in proportion to the accuracy of her work.

Before they finally worked to the best advantage it was found to be necessary to measure the output of each girl as often as once every hour, and to send a teacher to each individual who was found to be

falling behind to find what was wrong, to straighten her out, and to encourage and help her to catch up.

There is a general principle back of this which should be appreciated by all of those who are especially interested in the management of men.

Importance of Quick Rewards

A reward, if it is to be effective in stimulating men to do their best work, must come soon after the work has been done. But few men are able to look forward for more than a week or perhaps at most a month, and work hard for a reward which they are to receive at the end of this time.

The average workman must be able to measure what he has accomplished and clearly see his reward at the end of each day if he is to do his best. And more elementary characters, such as the young girls inspecting bicycle balls, or children, for instance, should have proper encouragement either in the shape of personal attention from those over them or an actual reward in sight as often as once an hour.

This is one of the principal reasons why cooperation or "profit-sharing" either through selling stock to the employees or through dividends on wages received at the end of the year, etc., have been at the best only mildly effective in stimulating men to work hard. The nice time which they are sure to have to-day if they take things easily and go slowly proves more attractive than steady hard work with a possible reward to be shared with others six months later. A second reason for the inefficiency of profit-sharing schemes had been that no form of cooperation has yet been devised in which each individual is allowed free scope for his personal ambition. Personal ambition always has been and will remain a more powerful incentive to exertion than a desire for the general welfare. The few misplaced drones, who do the loafing and share equally in the profits, with the rest, under cooperation are sure to drag the better men down toward their level.

Other and formidable difficulties in the path of cooperative schemes are, the equitable division of the profits, and the fact that, while workmen are always ready to share the profits, they are neither able nor willing to share the losses. Further than this, in many cases, it is neither right nor just that they should share either the profits or the losses, since these may be due in great part to causes entirely beyond their influence or control, and to which they do not contribute.

To come back to the girls inspecting bicycle balls, however, the final outcome of all the changes was that thirty-five girls did the work formerly done by one hundred and twenty. And that the accuracy of the work at the higher speed was two-thirds greater than at the former slow speed.

The good that came to the girls was,

First. That they averaged from 80 to 100 per cent higher wages than they formerly received.

Second. Their hours of labor were shortened from 10 1/2 to 8 1/2 per day, with a Saturday half holiday. And they were given four recreation periods properly distributed through the day, which made overworking impossible for a healthy girl.

Third. Each girl was made to feel that she was the object of especial care and interest on the part of the management, and that if anything went wrong with her she could always have a helper and teacher in the management to lean upon.

Fourth. All young women should be given two consecutive days of rest (with pay) each month, to be taken whenever they may choose. It is my impression that these girls were given this privilege, although I am not quite certain on this point.

The benefits which came to the company from these changes were:

First. A substantial improvement in the quality of the product.

Second. A material reduction in the cost of inspection, in spite of the extra expense involved in clerk work, teachers, time study, over-inspectors, and in paying higher wages.

Third. That the most friendly relations existed between the management and the employees, which rendered labor troubles of any kind or a strike impossible.

These good results were brought about by many changes which substituted favorable for unfavorable working conditions. It should be appreciated, however, that the one element which did more than all of the others was, the careful selection of girls with quick perception to replace those whose perceptions were slow--(the substitution of girls with a low personal coefficient for those whose personal coefficient was high)--the scientific selection of the workers.

First published 24 Dec 2020