Statistical Quality Control, 7th Edition

PART 6

Acceptance Sampling

Inspection of raw materials, semifinished products, or finished products is one aspect of quality assurance. When inspection is for the purpose of acceptance or rejection of a product, based on adherence to a standard, the type of inspection procedure employed is usually called acceptance sampling. This section presents two chapters that deal with the design and use of sampling plans, schemes, and systems. The primary focus is on lot-by-lot acceptance sampling.

Chapter 15 presents lot-by-lot acceptance-sampling plans for attributes. Included in the chapter is a discussion of MIL STD 105E and its civilian counterpart, ANSI/ASQC Z1.4. Variables sampling plans are presented in Chapter 16, including MIL STD 414 and its civilian counterpart, ANSI/ASQC Z1.9, along with a survey of several additional topics in acceptance sampling, including chain-sampling plans, sampling plans for continuous production, and skip-lot sampling plans.

The underlying philosophy here is that acceptance sampling is not a substitute for adequate process monitoring and control and use of other statistical methods to drive variability reduction. The successful use of these techniques at the early stages of manufacturing, including the supplier or supplier base, can greatly reduce and in some cases eliminate the need for extensive sampling inspection.