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- Herausgeber: John Wiley & Sons
- Kategorie: Fachliteratur
- Sprache: Englisch
Professor Woodall's essay shows that this book represents a remarkable contribution, even by today's standards, because of its contemporary thinking about the relationship between the specific topic of SQC and the broader company context of Quality Management. It also demonstrates the remarkable awareness of at least some young US engineers in the post-war period about the vital role of Statistical Quality Control in establishing and maintaining a competitive position. The book reveals that there was unsuspected knowledge extant immediately post-war, about the importance of Statistical Quality Control when appropriately applied in an industrial setting. It also helps to correct wide-spread historical misconceptions about who specifically was responsible for helping Japanese industry get back on its feet post-war, a task assigned to General Douglas Macarthur by President Truman and how Macarthur was indebted to Sarasohn.
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Table of Contents
Cover
Contents – Summary
Translators' Preface
Foreword
I Introduction
Preface
Step 1. Establishing the Quality Standard
Step 2. Establishing a Section to Evaluate Quality
Step 3. Establishing Inspection Standards
Step 4. Selection of Inspection Methods
Step 5. Investigation of the Current State of Quality
Technical Terms Used in Quality Control
II Probability and Statistical Inference
Measures of Central Tendency
Measure of Variability
III Sampling Inspection
Specifying an Acceptable Proportion of Defective Items
IV Application of Sampling Inspection
V Quality Control of the Production Process
AppendixStatistical Tables for Sampling Inspection
Thoughts on
The Road to Quality Control – The Industrial Application of Statistical Quality Control
by Homer M. Sarasohn
Introduction
Quality Management
Use of Acceptance Sampling
Control Chart Methods
Theory vs. Practice
Some Other Books of the Era
Conclusions
References
Homer Sarasohn and American Involvement in the Evolution of Quality Management in Japan, 1945–1950*
1 Introduction
2 Events Prior to 1945
3 1945–1947
4 1948–1950
5 Conclusions
6 Key Sources of Information
Acknowledgements
References
Résumé
Appendix: Notes on the Text
End User License Agreement
Guide
Cover
Table of Contents
Begin Reading
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The Road to Quality Control
The Industrial Application of Statistical Quality Control by
Homer M. Sarasohn
Translated by N.I. Fisher & Y. Tanaka from the original Japanese text published by Kagaku Shinko Sha with a historical perspective by W.H. Woodall and a historical context by N.I. Fisher
Copyright
This edition first published 2019
© 2019 John Wiley & Sons Ltd
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by law. Advice on how to obtain permission to reuse material from this title is available at http://www.wiley.com/go/permissions.
The right of N.I. Fisher, Y. Tanaka and W.H. Woodall to be identified as the authors of this translated work has been asserted in accordance with law.
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While the publisher and authors have used their best efforts in preparing this work, they make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of merchantability or fitness for a particular purpose. No warranty may be created or extended by sales representatives, written sales materials or promotional statements for this work. The fact that an organization, website, or product is referred to in this work as a citation and/or potential source of further information does not mean that the publisher and authors endorse the information or services the organization, website, or product may provide or recommendations it may make. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for your situation. You should consult with a specialist where appropriate. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this work was written and when it is read. Neither the publisher nor authors shall be liable for any loss of profit or any other commercial damages, including but not limited to special, incidental, consequential, or other damages.
Library of Congress Cataloging‐in‐Publication Data applied for
ISBN: 9781119514930
Cover Design: Wiley
Cover Image: Homer M. Sarasohn Archives: IBM Corporate Headquarters, New Orchard Rd; Armonk, New York 10504; (914) 499-1900
Contents – Summary
Homer M. Sarasohn
The Road to Quality Control: The Industrial Application of Statistical Quality Control
W.H. Woodall
“Thoughts on The Road to Quality Control: The Industrial Application of Statistical Quality Control by Homer M. Sarasohn”
N.I. Fisher
“Homer Sarasohn and American Involvement in the Evolution of Quality Management in Japan, 1945–1950”. Reprinted from International Statistical Review77, 276–299, with permission.
Translators' Preface
This book has unusual origins.
One of us (NIF) had the good fortune to form a close friendship with Homer Sarasohn in the last few years of his life. A few years after he passed away, in 2001, his daughter Lisa prepared his papers and other library materials for the Library of Congress. Some of his books were sent to his friends. Included in the resources sent to NIF was a small book written in Japanese but with the title also printed in English: The Industrial Application of Statistical Quality Control. The date of publication was given as 1951, making it a very early publication of any sort (let alone a book) on Statistical Quality Control, following Walter Shewhart's original publication. As such, it appeared to be a document of considerable historical interest, not least because of Homer's other work in Japan from 1946 to 1950.
Some time elapsed before permission was sought from Homer's family to arrange for a translation, which they kindly provided. Further delays have meant that it has taken nearly 15 years to bring the task of translation to completion. The translators also felt it important to provide some historical perspective for the book. This has been done by including two additional documents: one by an eminent academic researcher, Professor William Woodall, who kindly agreed to write an essay, positioning it in the published literature of the time, and the other a more general (previously published) article about Homer's work in Japan.
The background to the writing of this book is of some interest. In the early postwar years, Japanese engineers became aware of the widespread use of Statistical Process Control (SPC) in industry in the USA, and some perceived it as the driver for American manufacturing superiority.1 However, Homer resisted the pressure to teach SPC until such time as he had had the opportunity to educate people in the more general principles of industrial management so that they would appreciate the context in which SPC should be deployed. He and Charles Protzman conducted two courses (the so‐called CCS courses) for managers in Japanese industry late in 1949 to provide this education. At this point, he was able to turn his attention to teaching Statistical Quality Control. Taking into account the comment about delays in publication in the Foreword to this book, we can infer that it was written in 1950. It had been his intention to run courses in quality control himself. However, in 1950 General Douglas MacArthur was reassigned to another task (in Korea) and took Homer with him. Consequently, Homer contacted Walter Shewhart, who was too busy to assist but referred him to W. Edwards Deming, who then visited Japan in 1950 for this purpose.
The translators wish to acknowledge some initial work done on the translation by Professor Shu Yamada and some of his students.
We have taken the liberty of correcting a few very small errors in the text. The diagrams have been re‐drawn to reproduce the originals as closely as possible.
Finally, we note an irony that we feel would have amused Homer. As it happens, the last page we translated was the Foreword. We had assumed that Homer, who had taught himself Japanese, had written the book in Japanese. In fact, the Foreword reveals that this was not the case: it was translated into Japanese by an unknown team from Homer's original English script, so that we have, in effect, reverse engineered the book to approximate his original version.
N.I. Fisher
Y. Tanaka
Note
1
Cf. Interview of Homer Sarasohn by Myron Tribus in 1988,
http://honoringhomer.net/audio/interviews
(accessed 19 July 2018).
The Road to Quality Control
The Industrial Application of Statistical Quality Control by
Homer M. Sarasohn
Original Japanese version published by Kagaku Shinko Sha
Foreword
I owe Mr. Homer M. Sarasohn, the author of this book, very much for having taught me quality control. He had been working for the CCS of the GHQ. He is the person who proposed and executed an education program known as the “CCS course” for managers in Japanese industry. This book is his parting gift prepared on the basis of his belief that quality control is particularly important for Japanese industry. The main aim of his education program was to introduce quality control properly, in plain language, in a situation when there were few books available on quality control. Unfortunately, its publication was delayed for various reasons. Though it seems to me a little behind the times, I believe this kind of book is useful for readers because it is remains relevant. I regret there might be some parts that are not easy to read. It is because the translators have tried very hard to remain faithful to the original.
Mr. Homer M. Sarasohn now holds an important position in a company of management consultants named Booz, Allen & Hamilton, and is consulting for various large companies. Therefore, it may be said that this is a valuable book written by a first‐class consultant in the USA who knows Japanese industry very well.
I believe this book will provide basic information to beginners about quality control and will stimulate people who have had experiences in practicing quality control by providing them with an opportunity for self‐examination.
Finally, on behalf of the author, I thank those in the Japan Management Association for their efforts in making the translation.
Eizaburo Nishibori
IIntroduction
Preface
Product quality is an important matter in industry. It becomes more and more important given the recent trend that customers evaluate goods critically and make complaints about any issues that arise. Managers of companies, though they did not recognize it before, will now need to appreciate the following situation. In order for companies to be successful in modern society it is of fundamental importance for them to maintain the quality of products at the highest level possible, subject to operating profitably and producing products of uniform quality with reliable methods.
To realize this it is necessary to explain concretely to the managers of companies what management needs to do. The most important management principle for maintaining a high‐quality product is to establish company‐wide determination to serve their customers. After this is established and a firm decision is made to endeavor to maintain a reputation for high‐quality products, management should inform all the employees of this strict requirement for product quality. Managers should take the initiative in related activities. They should show with their behavior that quality is their company motto, and they also should try to ensure that the workplace environment is conducive to maintaining the highest possible product quality.
The policies for the control and management of a company should be practical and informed by progressive ideas, and they should be adhered to. Analyze the market to obtain the information on customer needs, then design and produce the products based on the result of analysis so that production is profitable. Calculate and control the costs required for planning, production, and control, and avoid waste. Whether or not it is possible to maintain high quality really depends on the design and the administrative efficiency of the company. From the above standpoint, treatment and training of the employees is very important.
It will be difficult to maintain the required level of product quality without management and employees being in perfect agreement about the meaning of quality. Employees, including those working in factories and those working in offices, should be trained so that they are willing to cooperate with management. They should be trained to contribute to producing products of high quality and to understand that their efforts will result in profit not only to the company but also to themselves.
Since such a way of thinking does not occur naturally, management should take the initiative in training activities. If good plans are incorporated into the training programs for mental activities as well as for physical labor, the effects would spread into every area of the company. The basic thinking needed to improve the quality of output is common in the divisions related to physical labor and mental activity.
So far, we have discussed the problem of quality from the standpoint of management. Now we discuss it from the standpoint of operation. A reliable consistent production process and products with uniform quality can be achieved only when the production process is planned and controlled using scientific methods for the purpose of producing products of high quality.
Design, production method, and standards for materials and process specification should be appropriate, accurate and efficient, and they should be obeyed strictly. Workers should be trained and supervised so that they can understand and carry out their jobs well. Machines, equipment, instruments, tools, and skills of workers should be suited to carrying out the required tasks within the assigned time using appropriate methods.
Even if all the above conditions are satisfied, however, it is not generally easy to maintain product quality. This is because there is a shortcoming in the control system in general management. Recently, a lot of research has been done to address this shortcoming, and as a result some tools have been developed. They are statistical methods developed for the purpose of maintaining the quality of the production process. Using these methods, we can determine product quality with pre‐assigned accuracy, and in addition we can improve the efficiency of production and also reduce costs. Scientifically speaking, the main aim of these methods is to control the factors that affect the quality of the final products going out to the market.
Establishment of a system of statistical quality control provides various advantages to the company as follows.
Variation of quality of the continuous production process is minimized.
Data based on samples taken from the production process provide reliable information to judge the state of the quality of the process.
Inspection cost (indirectly production cost) is minimized.
It is possible to obtain reliable basic information to test whether the current design and control limits for quality are appropriate or not.
It is possible to obtain practical basic information to assess the current production capability.
The results of sampling inspection usually provide proof of the actual quality of the products.
There can be no doubt that quality is the most essential foundation for a company to be successful. This has been demonstrated by many substantial companies. Quality is recognized as the most important matter. Therefore, it is necessary to position quality as the sound logical foundation for management and to adopt quality control as one of the valuable control methods among the industrial factors that are vital to the prosperity of the company.
There are two fundamental tasks necessary for successful practice of quality control. They are (1) to set up a system of control, and (2) to execute the actions resulting from the system of control.
The latter requires the support of management to ensure that the newly established system of control has a chance to work successfully; while the former provides the technical means, within which statistical quality control plays the principal role. We shall discuss these matters in detail below. There are some preliminary steps required to set up the initial control system. You should perform these logical steps one by one. However, as it is not essential to complete one step before proceeding to the next, it is sometimes convenient to perform some steps in parallel.
Step 1. Establishing the Quality Standard
Product quality captures the special characteristics useful for discriminating one's products from those of rival companies, special characteristics for discriminating among the same kind of products, or special characteristics for grading the products of the same production process. There are two purposes for quality. One is to demonstrate that two or more products are in the same category, as occurs when comparing the products manufactured by rival companies. The other is as a measure of fitness for purpose.
In either case quality is not measured on an absolute scale but merely on a relative scale. One can say that something is good from a certain point of view only when it is compared with some standard on a one‐dimensional scale. In such cases quality becomes a variable and the result of a comparison can be expressed as quality being higher or lower (better or worse) than the standard.
When defining the quality of a product, possible characteristics related to the goodness of quality include size, materials, shape, chemical components, function, fitness for purpose, appearance, and practicability. These characteristics depend on (a) quality of design or (b) quality compared with the standard. The former relates to technical specification for manufacturing, and the latter relates to the method for comparing with the standard and the extent of difference from the standard.
Quality of design includes the problem of the trade‐off between cost and outcome. It is a commercial issue to be considered carefully by both engineers and administrators. Consider an ideal case where engineers design a product with the best quality. If nobody buys the product in the market because of high cost, the idealistic engineers are to blame. If the engineers pursue high product quality simply for the sake of quality itself without any consideration for the practical use of the product, they are not fulfilling their duties. The engineers are responsible for the commercial aspect of the product as well.
If the accuracy of size, chemical purity, or any other quality attribute improves, the value of the product increases, but so does the cost. Eventually, comparing the additional value of the product that is due to an improvement of quality and the increase in cost required for the improvement, the point at which the latter exceeds the former will be the limit for quality improvement. Therefore, it is necessary for the engineers involved in production engineering and those involved in the production process to set the quality standard so that the standard is consistent with the reason for producing the product while the cost remains commercially viable.
The problem of quality versus cost discussed above also occurs in connection with quality compared with the technical standard. For example, suppose there is a production process in which 0.1% defective items are constantly produced. That is, on average there is one unit whose quality is below the required level among 1000 units produced in a day. It is necessary to inspect 1000 units per day in order to detect one defective unit. Ordinarily the inspection cost for 1000 units is much higher than the cost of the loss or inconvenience of a customer who buys the defective unit. In such cases it seems it is more economical not to carry out 100% inspection. It reduces the cost if we perform sampling inspection instead of 100% inspection, to gain assurance that the percent defective is less than 0.1%. Customers will be satisfied if an agreement is made in advance such that, when a customer happens to buy a defective unit, it will be replaced by a non‐defective one or the possible loss will be compensated. The reason is that the cost required for 100% inspection causes an increase in the price of the product, which is not good for customers.
As the cost of quality is a vital factor in establishing the quality standard for the design or the technical standards, management should cooperate with the engineers to try to strike an appropriate balance between the cost of maintaining quality and the market price of the products. Among many factors that affect this issue, the main ones are as follows.
Desire of the manufacturer to maintain their reputation with their customers.
Quality of product design.
Skills of workers and quality of machines or tools needed to meet the prescribed quality requirements.
Research into target market, market needs for functionality, and requests from the market for practicability and price.
Rapid management capability to get access to raw materials.
Other economic factors related to achieving the required quality with reasonable production cost.
Step 2. Establishing a Section to Evaluate Quality
Having chosen the appropriate quality standard, it is necessary to establish a section to assess whether or not the produced products conform to the quality policy of the company. The assessment is made by inspectors in the company. Inspectors have duties to test the products against the quality standard set by engineers in the company. The relation between inspectors and the company is just like the relation between public prosecutors and a democratically elected government. In the case of government it consists of three independent divisions, viz. divisions of administration, legislature, and prosecution, for mutual inspection and maintaining balance. The administration practices the law which is made by the legislature, and the prosecutors check on whether the law is violated.
In a company, the administration division is represented by the chief officer and the general manager. For manufacturing, the duty of the legislature is practiced by the department of design. The duty of inspection is similar to that of prosecution: the inspectors judge whether the products satisfy the quality requirements by comparing them with the specification and standard decided by the department of design.
Of course, quality must be built into a product. It is not possible to change defective items to non‐defective ones by inspection. The quality of products is not determined by inspection. An inspector's responsibility is simply to judge whether or not quality is of the required level.
Generally, responsibility is divided as described above, that is, the inspection department operates independently of the division of manufacturing. This is because in most companies it is desirable and necessary to do so.
Thus the three divisions, that is, the planning division for deciding on designs and standards, the manufacturing division for producing products based on the designs, and the inspection division for evaluating the quality level, are of the same rank and have their own independent functions.
If product quality is below the quality standard, it will be due to one or both of the following reasons: (1) design and specification made by the planning division are not good; or (2) the manufacturing division cannot produce products according to the design and specification, either because of a lack of capability or because of failures in the manufacturing process. It is important to keep the inspection division independent of the planning and manufacturing divisions in order to maintain the reputation of the quality of the products. When product quality is lower than the required level, the inspectors should point this out objectively, and clarify where the responsibility lies, with the cooperation of other appropriate sections. In fact, the inspectors should, to a certain extent, be independent of both of the design and manufacturing divisions in relation to stabilizing the company's product quality. In extreme cases, such as when defective items are being produced continually, the inspection division should have the authority to restrict the activity of the manufacturing division until the cause is found and removed. If there are any mistakes in the design of the product (or a component of the product) or in the system of manufacturing, the inspection division should be able to ask the design division to modify the design in order to remove the causes.
The main aims of inspection are not only to detect defects and remove them in the production process but also, more importantly, to prevent the production of defective items. Inspectors should have skills of a high level, and therefore the selection and training of inspectors is very important for the company. The reputation of the quality of the products – and therefore the reputation of the company – depend heavily on the skills, judgment, and honesty of the inspectors.
However, the rejection rate might become high owing to careless inspection or inaccuracy of measurement, even though both the design and production methods are not poor. It is not acceptable for inspectors who judge the quality of work done by other people to make mistakes in their own jobs. Inspectors should not make any mistakes because of a lack of attention to details, an irresponsible attitude in their daily jobs, or inappropriate or maladjusted machines or equipment.
Inspectors need to understand the importance of their role. They should be provided with the equipment necessary to carry out inspection, they should be aware of the necessity to interact objectively and cooperatively with people in other sections, and they should be trained well for their jobs. Of course, the manager also needs to have a very good understanding of the duties of the inspectors and to supervise them sensibly, so that if one of them happens to make a mistake in performing his job, the manager does not take him to task inappropriately.
Step 3. Establishing Inspection Standards
For production control it is necessary to start by establishing a series of inspection standards. The standards include identifying which objects are to be inspected; methods, instruments, and equipment to be used; conditions of inspection; the standard procedure for each inspection; the classification scheme for characteristics to be inspected; and the relative importance of inspected items.
Inspection standards consist of standards for (a) raw materials, (b) processing, (c) final products, and (d) their functions. The quality of purchased raw materials or parts or outsourced processed goods is checked for conformance to the inspection standards for raw materials. Inspection standards for processing are used to check characteristics such as shape, size, look, and finish of the intermediate products. Inspection standards for final products are used to check whether the final product matches the quality of design. When many parts are assembled into a large system the standards are used to check the functioning of the entire system.
These standards are written by the leaders of the design and engineering division or the production division, in accordance with company policy. The appropriate people to write standards describing the technical requirements will be chosen from those responsible for inspection. Inspection standards written in this way will be distributed to all inspectors, and they will be used just like the Bible.
Step 4. Selection of Inspection Methods
There are various kinds of inspection applied in industry. They include inspection of tools, inspection of the first product, patrol inspection, inspection of the process, concentrated inspection, and final inspection. Which of these varieties of inspection are applied depends on the purpose. Inspection of tools is used in the cases of frequently repeated operations to produce the same parts with the same equipment: for example an automatic stamping press machine. In such cases, the tools and forms are inspected for deterioration and damage rather than inspecting the components being produced.
Inspection of the initial product is also used in the cases of repetitious operations. The operation is checked completely for conformance to the requirements. If the first product conforms, it is assumed that subsequent operations should be all right. However, this approach will not be adequate in cases where most operations are manual and the operators are neither trained well nor supervised closely.
Patrol inspection is a method described by its name. Patrolling inspectors take small samples from the production process and check the quality of intermediate products.
Process inspection is what is most commonly applied. It takes place when proceeding from one process to the next process.
