This Part specifies generic skip-lot sampling procedures for acceptance inspection by attributes. The purpose of these procedures is to provide a way of reducing the inspection effort on products of high quality submitted by a supplier who has a satisfactory quality assurance system and effective quality controls. The reduction in inspection effort is achieved by determining at random, with a specified probability, whether a lot presented for inspection will be accepted without inspection. These procedures extend the principle of the random selection of sample items already applied in GB/T 2828.1 to the random selection of lots.
The skip-lot sampling procedures specified in this part are applicable to, but not limited to, inspection of
a) End items, such as complete products or sub-assemblies,
b) Components and raw materials, and
c) Materials in process.
The following normative document contains provisions which, through reference in this text, constitute provisions of this Part. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, parties to agreements based on this standard are encouraged to investigate the possibility of applying the most recent edition of the normative document indicated below. For undated references, the latest edition of the normative document referred to applies.
GB/T 2828.1-2003 Sampling procedures for inspection by attributes - Part 1: Sampling Schemes Indexed by Acceptance Quality Limit (AQL) for Lot-by-lot Inspection
ISO 3534-1 Statistics - Vocabulary and symbols - Part 1: Probability and general statistical terms
ISO 3534-2 Statistics - Vocabulary and symbols - Part 2: Applied statistics
Contents
1 Scope 1
2 Normative references 1
3 Terms, definitions and symbols 1
3.1 Terms and definitions 1
3.2 Symbols and abbreviated terms 3
4 General requirements 3
5 Supplier and product qualification 4
5.1 Supplier qualification 4
5.2 Product qualification 5
5.3 Qualification score 6
5.4 Example for product qualification 8
6 Skip-lot sampling procedures 9
6.1 General 9
6.2 Initial inspection frequency and its determination 11
6.3 Inspection frequency and shifting 11
6.4 Sampling plans, lot selection and inspection procedures (States 2 and 3) 15
6.5 Skip-lot interruption 16
6.6 Requalification 17
6.7 Product disqualification 17
6.8 Supplier disqualification and suspension 18
7 Supplier responsibilities 19
8 Inspection agency and responsible authority responsibilities 20
8.1 General 20
8.2 Responsibilities on supplier qualification 20
8.3 Other responsibilities 20
9 Compatibility with GB/T 2828.1 21
9.1 Limitations 21
9.2 Relation to reduced inspection 22
10 Additional information 22
10.1 Design basis 22
10.2 Statistical characteristics of the skip-lot procedures 22
Appendix A (normative) Optional requirements to be agreed prior to product qualification 25
Appendix B(normative) Procedures for random selection at specified inspection frequency 26
Appendix C (informative) Factors used in deciding between skip-lot inspection and reduced inspection 28
Bibliography 30
