Introduction to Statistical Quality Control, 5th edition.doc

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1、COURSE MATERIAL FOR VTU: By: Prof.N.S.Narahari,Director Placement and Training, R.V.College of Engineering,RV Vidyaniketan Post, 8th Mile,Mysore Road, Bangalore 560 059.CONTENT SHEET:SessionsDescriptionPage Nos.Session 1Basics of Quality : Definition of Quality, Quality Function, Dimensions of Quali

2、ty, Quality Engineering Terminology, brief history of quality methodology, Statistical methods of quality improvement3-21Session 2Quality costs - four categories costs and hidden costs23-24Session 3Principles of Quality: Brief discussion on sporadic and chronic quality problems. Introduction to qual

3、ity function Deployment26-27Session 4Quality Assurance : Definition and concept of quality assurance, Departmental assurance Activities29-30Session 5Quality Audit : Quality audit concept, audit approach etc. structuring the audit program, planning and performing audit activities, audit reporting, in

4、gredients of a quality program32-53Session 6Statistical Process Control Basics : Introduction to statistical process control, chance and assignable causes variation55-61Session 7Basic Principles of control charts, choice of control limits, sample size and sampling frequency, rational sub groups63-68

5、Session 8Patterns of Control Charts : Analysis of patterns of control charts, case studies on application of SPC70-76Session 9Seven QC Tools78-91Session: Basics of QualityCourse Material of VTU EDUSAT Program: Session 1 :1.0 : Definitions and Meaning of QualityDefinition Quality means fitness for us

6、e. Quality is inversely proportion to variability - This is a modern definition of quality This is a traditional definition Quality of design Quality of conformanceThe Transmission ExampleDefinition Quality Improvement is the reduction of variability in processes and product. The transmission exampl

7、e illustrates the utility of this definition An equivalent definition is that quality improvement is the elimination of waste. This is useful in service or transactional businesses.1.1 : The Eight Dimensions of Quality 1. Performance 2. Reliability 3. Durability 4. Serviceability 5. Aesthetics 6. Fe

8、atures 7. Perceived Quality 8. Conformance of Standards Suppliers and supply chain management must be involved Must focus on all three components: Quality Planning, Quality Assurance, and Quality Control & Improvement1.2 : TerminologyEvery product possesses a number of elements that jointly describe

9、 what the user or consumer thinks of as quality. These parameters are often called quality characteristics. Sometimes these are called critical-to-quality (CTQ) characteristics. Quality characteristics may be of several types:1. Physical: length, weight, voltage, viscosity. 2. Sensory: taste, appear

10、ance, color. 3. Time Orientation: reliability, durability, serviceability, Since variability can only be described in statistical items, statistical methods play a central role in quality improvement efforts. In the application of statistical methods to quality engineering, it is fairly typical to c

11、lassify data on quality characteristics as either attributes or variables data. Variables data are usually continuous measurements, such as length, voltage, or viscosity. Attributes data, on the other hand, are usually discrete data, often taking the form of counts. We will describe statistical base

12、d quality engineering tools for dealing with both types of data. Specifications Lower specification limit Upper specification limit Target or nominal values Defective or nonconforming product Defect or nonconformity Not all products containing a defect are necessarily defective1.3 : History of Quali

13、ty Improvement : 1.4 : Statistical Methods for Quality Control and ImprovementProduction process inputs and outputsStatistical Methods Statistical process control (SPC) Control charts, plus other problem-solving tools Useful in monitoring processes, reducing variability through elimination of assign

14、able causes On-line technique Designed experiments (DOX) Discovering the key factors that influence process performance Process optimization Off-line technique Acceptance SamplingWalter A. Shewart (1891-1967) Trained in engineering & physics Long career at Bell Labs Developed the first control chart

15、 about 1924A factorial experiment with three factorsVariations of acceptance sampling1.5 : Management aspects of Quality Improvement Effective management of quality requires the execution of three activities:1. Quality Planning2. Quality Assurance3. Quality Control and Improvement1.6 : Quality plann

16、ing is a strategic activity, and it is just as vital to an organizations long-term business success as the product development plan, the financial plan, the marketing plan, and plans for the utilization of human resources. Without a strategic quality plan, an enormous amount of time, money, and effo

17、rt will be wasted by the organization dealing with faulty designs, manufacturing defects, field failures, and customer complaints. Quality planning involves identifying customers, both external and those that operate internal to the business, and identifying their needs (this is sometimes called lis

18、tening to the voice of the customer). Then product or services that meet or exceed customer expectations must be developed. The Organizations must then determine how these products and services will be realized. Planning for quality improvement on a specific, systematic basis is also a vital part of

19、 this process. 1.7 : Quality assurance is the set of activities that ensures the quality levels of products and services are properly maintained and that supplier and customer quality issues are properly resolved. Documentation of the quality system is an important component. Quality system document

20、ation involved four components: policy, procedures, work instructions and specifications, and records. Policy generally deals with what is to be done and why, while procedures focus on the methods and personnel that will implement policy. Work instructions and specifications are usually product-, de

21、partment-, tool-, or machine-oriented. Records are a way of documenting the policies, procedures, and work instruction that have been followed. Records are also used to track specific units or batches of products, so that it can be determine exactly how they were produced. Records are often vital in

22、 providing data for dealing with customer complaints, corrective actions, and, it necessary, product recalls. Development, maintenance, and control of documentation are important quality assurance functions. One example of document control is ensuring that specifications and work instructions develo

23、ped for operating personnel reflects the latest design and engineering changes. 1.8 : Quality control and improvement involve the set of activities used to ensure that the products and services meet requirements and are improved on a continuous basis. Since variability is often a major source of poo

24、r quality, statistical techniques, including SPC and designed experiments, are the major tools of quality control and improvement. Quality improvement is often done on a product-by-project basis and involved teams led by personnel with specialized knowledge of statistical methods and experience in a

25、pplying them. Projects should be selected so that they have significant business impact and are linked with the overall business goals for quality identified during the planning process. The techniques in this book are integral to successful quality control and improvement. 1.9 : Quality Philosophie

26、s and Management StrategiesW. Edwards Deming Taught engineering, physics in the 1920s, finished PhD in 1928 Met Walter Shewhart at Western Electric Long career in government statistics, USDA, Bureau of the Census During WWII, he worked with US defense contractors, deploying statistical methods Sent

27、to Japan after WWII to work on the census Deming Deming was asked by JUSE to lecture on statistical quality control to management Japanese adopted many aspects of Demings management philosophy Deming stressed “continual never-ending improvement” Deming lectured widely in North America during the 198

28、0s; he died 24 December 1993Demings 14 Points1. Create constancy of purpose toward improvement 2. Adopt a new philosophy, recognize that we are in a time of change, a new economic age3. Cease reliance on mass inspection to improve quality4. End the practice of awarding business on the basis of price

29、 alone5. Improve constantly and forever the system of production and service 6. Institute training7. Improve leadership, recognize that the aim of supervision is help people and equipment to do a better job8. Drive out fear9. Break down barriers between departments10. Eliminate slogans and targets f

30、or the workforce such as zero defects11. Eliminate work standards12. Remove barriers that rob workers of the right to pride in the quality of their work13. Institute a vigorous program of education and self-improvement14. Put everyone to work to accomplish the transformationDemings Deadly Diseases1.

31、 Lack of constancy of purpose2. Emphasis on short-term profits3. Performance evaluation, merit rating, annual reviews4. Mobility of management5. Running a company on visible figures alone6. Excessive medical costs for employee health care7. Excessive costs of warranteesJoseph M. Juran Born in Romani

32、a (1904), immigrated to the US Worked at Western Electric, influenced by Walter Shewhart Emphasizes a more strategic and planning oriented approach to quality than does Deming Juran Institute is still an active organization promoting the Juran philosophy and quality improvement practicesThe Juran Tr

33、ilogy1. Planning2. Control3. Improvement These three processes are interrelated Control versus breakthrough Project-by-project improvementSome of the Other “Gurus” Kaoru Ishikawa Son of the founder of JUSE, promoted widespread use of basic tools Armand Feigenbaum Author of Total Quality Control, pro

34、moted overall organizational involvement in quality, Three-step approach emphasized quality leadership, quality technology, and organizational commitment Lesser gods, false prophets Total Quality Management (TQM) Started in the early 1980s, Deming/Juran philosophy as the focal point Emphasis on wide

35、spread training, quality awareness Training often turned over to HR function Not enough emphasis on quality control and improvement tools, poor follow-through, no project-by-project implementation strategy TQM was largely unsuccessful TQM is “just another program” Value engineering Zero defects “Qua

36、lity is free”1.10 : Quality Systems and StandardsThe International Standards Organization (founded in 1946 in Geneva, Switzerland), known as ISO, has developed a series of standards for quality systems. The first standards were issued in 1987. The current version of the standard is known as the ISO

37、9000 series. It is a generic standard, broadly applicable to any type of organization, and it is often used to demonstrate a suppliers ability to control its processes. The three standards of ISO 9000 are: ISO 9000:2000 Quality Management System Fundamental and Vocabulary ISO 9000:2000 Quality Manag

38、ement System Requirements ISO 9000:2000 Quality Management System Guidelines for Performance improvement The ISO 9001:2000 standard has eight clauses: (1) Scope, (2) Normative References, (3) Definitions, (4) Quality Management Systems, (5) Management Responsibility, (6) Resource Management, (7) Pro

39、duct (or service) Realization, and (8) Measurement, Analysis, and Improvement. To become certified under the ISO standard, a company must select a register and prepare for a certification audit by this registrar. There is no single independent authority that license, regulates, monitors, or qualifie

40、s registrars. As we will discuss later, this is a serious problem with the ISO system. Preparing for the certification audit involved many activities including (usually) an initial or phase I audit that checks the present quality management system against the standard. This is usually followed by es

41、tablishing teams to ensure that all components of the key clause are developed and implemented, training of personnel, developing applicable documentation, and developing and installing all new components of the quality system that may be required. Then the certification audit takes placed. If the c

42、ompany is certified, then periodic surveillance audits by the registrar continue, usually on an annual (or perhaps six months) schedule. The ISO certification process focuses heavily on quality assurance, without sufficient weight given to quality planning and quality control and improvementThere is

43、 also evidence that ISO certification or certification under one of the other industry-specific standards does little to prevent poor quality products from being designed, manufactured, and delivered to t he customer. For example, in 1999-2000, there were numerous incidents of rollover accidents inv

44、olving Ford Explorer vehicles equipped with Bridgestone / Firestone tires and there were nearly 300 deaths in the United States alone attributed to these accidents, which les to a recall by Bridgestone / Firestone of approximately 6.5 million tires. Apparently, many of the tires involved in these in

45、cidents were manufactured at the Bridgestone / Firestone plant in Dectur, Illionis. In an article on this story in Time magazine (Sept. 18, 2000), there was a photograph (p.38) of the sign at the entrance of the Decatur plant which stated that the plant was “QS 9000 Certifies” and ISO 14001 Certifie

46、d” (ISO 14001 is an environmental standard). Although the assignable causes underlying these incidents have not been fully discovered, there are clear indicators that despite quality systems certification, Bridgestone / Firestone experienced significant quality problems The Malcolm Baldrige National

47、 Quality AwardThe Malcolm Baldrige National Quality Award (MBNQA) was created by the US Congress in 1987. It is given annually to recognize US corporations for performance excellence. Awards are given to organizations in five categories: manufacturing, service, small business, health care, and education. Three awards many be given each year in each category. Many organizations compete for the awards, and many companies use the performance excellence criteria for self-assessment. The award is administered by NIST (the National Bureau of Standards and Technology). The