PART 43—STANDARDS FOR SAMPLING PLANS Authority: Secs. 203, 205, 60 Stat. 1087, as amended, 1090, as amended; 7 U.S.C. 1622, 1624. Source: 29 FR 5870, May 5, 1964, unless otherwise noted. Redesignated at 42 FR 32514, June 27, 1977, and further redesignated at 46 FR 63203, Dec. 31, 1981. Definitions § 43.101 Meaning of words. Words used in this subpart in the singular form shall be considered to impart the plural, or vice versa, as the case may demand. § 43.102 Definitions. Statistical and inspection or sampling terms and their respective definitions that are used in the sampling plans and operating characteristic curves of which are pertinent to the understanding of inspection by attributes follow: Acceptable quality level AQL Acceptance number Ac Acceptance sampling. Attributes. Consumer's risk. Consumer protection. Defect. Defective. Inspection. (a) Acceptance inspection. (b) Estimation inspection. Inspection by attributes. Limiting quality LQ Lot. Lot size. Operating characteristic curve OC curve Probability of acceptance Pa Process capability. Producer's risk. Random sampling. Rejection number Re Sample. Sample size. Sample unit. Sampling. Sampling plan. (a) Single sampling plan. (b) Double sampling plan. 1 t Sampling Plans § 43.103 Purpose and scope. (a) This subpart contains selected single and double sampling plans for inspection by attributes. They are to serve as a source of plans for developing sound specifications, standards, or sampling and inspection procedures. (b) The sampling plans of this subpart and corresponding operating characteristic curves are indexed by acceptable quality level, AQL. The AQL's expressed in percent defectives or defects per hundred units are: 0.065 0.40 2.5 8.5 0.10 0.65 4.0 10.0 0.15 1.0 5.0 12.5 0.25 1.5 6.5 15.0 § 43.104 Master table of single and double sampling plans. (a) In the master table, a sampling plan is selected by first determining the sample size or sizes and AQL to be used. Then find the applicable acceptance (Ac) and rejection (Re) numbers at the intersection of the sample size(s) row and AQL column. These numbers together with the sample size or sizes constitute a sampling plan. (b) Single sampling plans having a sample size of 66 or greater and an acceptance number of 1 are not included in the Master Table. These plans are listed in the tables which supplement the Master Table and accompany the OC curves as indexes to the comparable double sampling plans. The use of these single sampling plans do not facilitate the practice of using two or more AQL's simultaneously with the same sample size. § 43.105 Operating characteristics (OC) curves. The OC curves shows the ability of the various sampling plans, presented for each AQL, to distinguish between lots of different quality. § 43.106 Choosing AQL's and sampling plans. (a) The selection of AQL's and sampling plans for given lot sizes depends on too many factors to permit the issuance of a “pre-selected” standard set of plans for specified lot sizes. Each user of the standards of this subpart should select AQL's and sampling plans that are tailored to best meet his needs. (b) Some of the factors that must be considered prior to selecting the AQL's are: (1) Class of defects such as major and minor: Major defects would generally require lower AQL's than those for minor defects; (2) Process capabilities under good commercial practice with respect to the defects in question: For example, if under normal production processes, the defect level cannot be kept below 2.0 percent defective, the selection of an AQL of 0.15 percent defective, although desirable for the defects in question, may not be practical; (3) Consumer preferences: These may require higher AQL's or permit lower AQL's than process capabilities would indicate; and (4) Time and cost required to sample and inspect a lot under various AQL's: The smaller the AQL the more time and cost of inspection. (c) Some of the factors that may be considered prior to selecting the sampling plans for given lot sizes are: (1) The applicable AQL(s): The AQL dictates, among other things, the smallest sample size that can be used and the size of the “jumps” from one sample size to the next larger one; (2) The relative ability of the plans to discriminate between “good” and “bad” lots: Although several plans in these standards have the same AQL, they differ in their ability to reject lots worse than the AQL's. The OC curve in the standards of this subpart provide the basis for determining the discriminating ability of each plan; (3) The amount, time, and cost of sampling required; (4) The size and value of the lots relative to the producer and consumer protection a sampling plan affords: One may be willing to take larger risks of passing “bad” lots that are small or of lesser value than they would for larger more valuable lots; (5) The knowledge about the lot(s) to be submitted for inspection: Lots consisting of product produced under essentially the same conditions may require smaller sample sizes than those consisting of product produced by different shifts and different raw stock for example; and (6) The record of the quality level of previously submitted lots: The sample size can be smaller for lots submitted from a supplier with a consistent record of quality levels significantly better than the specified AQL(s) than sample sizes for the supplier whose records show considerable variability in quality, “borderline” supplies or product worse than the AQL. Master Table of Single and Double Sampling Plans 1 Sample size code letter Sample size Acceptable quality levels 0.065 0.10 0.15 0.25 0.40 0.65 1.0 1.5 2.5 4.0 5.0 6.5 8.5 10.0 12.5 15.0 Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re Ac Re AA n 1 0 1 A n 1 0 1 B n 1 0 1 0 3 1 2 n t 2 3 C n 1 0 1 1 2 D n 1 0 1 1 2 E n 1 1 2 2 3 EE n 1 2 3 F n 1 0 1 1 2 2 3 3 4 G n 1 1 2 2 3 3 4 H n 1 0 1 2 3 3 4 4 5 J n 1 0 1 0 2 0 2 2 3 1 4 3 4 3 5 4 5 5 6 6 7 n t 1 2 2 3 3 4 5 6 K n 1 0 1 0 2 1 2 2 3 1 4 3 4 4 5 3 7 5 6 6 7 7 8 n t 1 2 6 7 9 10 L n 1 0 1 0 2 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 10 11 11 12 n t 1 2 M n 1 0 1 0 2 0 3 2 3 3 4 4 5 6 7 7 8 9 10 11 12 13 14 15 16 18 19 n t 1 2 n t 2 3 N n 1 0 1 0 2 0 3 2 3 3 4 4 5 6 7 9 10 10 11 13 14 16 17 18 19 22 23 26 27 n t 1 2 n t 2 3 P n 1 0 1 0 2 0 3 2 3 3 4 4 5 6 7 9 10 13 14 15 16 19 20 24 25 27 28 33 34 39 40 n t 1 2 n t 2 3 Q n 1 0 1 0 2 0 2 3 3 4 4 5 6 7 8 9 13 14 19 20 22 23 28 29 35 36 41 42 50 51 59 60 n t 1 2 n t 2 3 R n 1 0 2 0 3 2 3 3 4 4 5 6 7 9 10 12 13 18 19 28 29 33 34 42 43 53 54 62 63 76 77 90 91 n t 1 2 n t 2 3 S n 1 0 3 2 3 3 4 4 5 6 7 9 10 13 14 18 19 27 28 42 43 50 510 64 65 82 83 95 96 117 118 140 141 n t 2 3 T n 1 2 3 3 4 4 5 6 7 9 10 13 14 19 20 26 27 41 42 63 64 76 77 U n 1 3 4 4 5 6 7 9 10 13 14 19 20 28 29 39 40 62 63 96 97 1 1 t Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.065 Percent Defective (or AQL=0.065 Defects per Hundred Units) [Sampling plans—AQL=0.065] Comparable sampling plans Identification letter of OC curve Q R S, T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 315 0 1 624 1 2 1250 2 3 2,000 3 Double 500 0 2 800 0 3 644 1 2 1304 2 3 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.10 Percent Defective (or AQL=0.10 Defects per Hundred Units) [Sampling plans—AQL=0.10] Comparable sampling plans Identification letter of OC curve P Q R, S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 200 0 1 408 1 2 800 2 3 1,250 3 4 2,000 4 Double 315 0 2 500 0 3 435 1 2 836 2 3 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.15 Percent Defective (or AQL=0.15 Defects per Hundred Units) [Sampling plans—AQL=0.15] Comparable sampling plans Identification letter of OC curve N P Q R, S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 126 0 1 264 1 2 500 2 3 800 3 4 1,250 4 5 2,000 6 7 Double 200 0 2 315 0 3 284 1 2 519 2 3 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.25 Defects per Hundred Units [Sampling plans—AQL=0.25] Comparable sampling plans Identification letter of OC curve M N P, Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 84 0 1 168 1 2 315 2 3 500 3 4 800 4 5 1250 6 7 2000 9 10 Double 126 0 2 200 0 3 180 1 2 326 2 3 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.40 Percent Defective (or AQL=0.40 Defects per Hundred Units) [Sampling plans—AQL=0.40] Comparable sampling plans Identification letter of OC curve L M N, P Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 48 0 1 108 1 2 200 2 3 315 3 4 500 4 5 800 6 7 1250 9 10 2000 13 10 Double 84 0 2 126 0 3 120 1 2 210 2 3 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=0.65 Percent Defective (or AQL=0.65 Defects per Hundred Units) [Sampling plans—AQL=0.65] Comparable sampling plans Identification letter of OC curve K L M, N P Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 29 0 1 66 1 2 126 2 3 200 3 4 315 4 5 500 6 7 800 9 10 1250 13 14 2000 19 20 Double 48 0 2 84 0 3 72 1 2 132 2 3 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=1.0 Percent Defective (or AQL=1.0 Defects per Hundred Units) [Sampling plans—AQL=1.0] Comparable sampling plans Identification letter of OC curve J K, L M N P n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 21 0 1 48 1 2 84 2 3 126 3 4 200 4 5 Double 29 0 2 65 1 2 Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 315 6 7 500 9 10 800 13 14 1250 19 20 2000 28 29 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=1.5 Percent Defective (or AQL=1.5 Defects per Hundred Units) [Sampling plans—AQL=1.5] Comparable sampling plans Identification letter of OC curve H J, K L M N P n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 13 0 1 29 1 2 48 2 3 84 3 4 126 4 5 200 6 7 Double 21 0 2 31 1 2 Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 315 8 9 500 12 13 800 18 19 1,250 26 27 2,000 39 40 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=2.5 Percent Defective (or AQL=2.5 Defects per Hundred Units) [Sampling plans—AQL=2.5] Comparable sampling plans Identification letter of OC curve F J, K L M N P n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 9 0 1 29 2 3 48 3 4 84 4 5 126 6 7 200 9 10 Double 21 0 2 31 2 3 Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 315 13 14 500 18 19 800 27 28 1,250 41 42 2,000 62 63 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=4.0 Percent Defective (or AQL=4.0 Defects per Hundred Units) [Sampling plans—AQL=4.0] Comparable sampling plans Identification letter of OC curve D G J K L M N n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 5 0 1 11 1 2 21 2 3 48 4 5 84 6 7 126 9 10 Double 29 1 4 65 6 7 P Q R S T U n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 200 13 14 315 19 20 500 28 29 800 42 43 1250 63 64 2000 96 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=5.0 Percent Defective (or AQL=5.0 Defects per Hundred Units) [Sampling plans—AQL=5.0] Comparable sampling plans Identification letter of OC curve C F J, K L M N n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 4 0 1 1 1 2 29 3 4 48 5 6 84 7 8 126 10 11 Double 21 1 4 31 3 4 P Q R S T n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 200 15 16 315 22 23 500 33 34 800 50 51 1250 76 77 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=6.5 Percent Defective (or AQL=6.5 Defects per Hundred Units) [Sampling plans—AQL=6.5] Comparable sampling plans Identification letter of OC curve B E H J K L n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 3 0 1 6 1 2 13 2 3 21 3 4 29 4 5 48 6 7 M N P Q R S n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 84 9 10 126 13 14 200 19 20 315 28 29 500 42 43 800 64 65 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=8.5 Percent Defective (or AQL=8.5 Defects per Hundred Units) [Sampling plans—AQL=8.5] Comparable sampling plans Identification letter of OC curve D G J K, L M n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 5 1 2 11 2 3 24 4 5 48 7 8 84 11 1 Double 21 3 5 29 3 7 31 5 6 65 9 10 N P Q R S n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 126 16 17 200 24 25 315 35 36 500 53 54 800 82 83 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=10.0 Percent Defective (or AQL=10.0 Defects per Hundred Units) [Sampling plans—AQL=10.0] Comparable sampling plans Identification letter of OC curve A C F H J K L n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 2 0 1 4 1 2 9 2 3 13 3 4 21 4 5 29 5 6 48 8 9 M N P Q R S n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 84 13 14 126 18 19 200 27 28 315 41 42 500 62 63 800 95 96 n c Sampling Plans and Operating Characteristics (OC) Curves for AQL=12.5 Percent Defective (or AQL=12.5 Defects per Hundred Units) [Sampling plans—AQL=12.5] Identification letter of OC curve Comparable sampling plans B, EE G J K L M n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 7 2 3 11 3 4 21 5 6 29 6 7 48 10 11 84 15 16 Double 3 0 3 8 2 3 N P Q R S n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 126 22 23 200 33 34 315 50 51 500 76 77 800 117 118 n c Sampling Plans and Operating Characteristic (OC) Curves for AQL=15.0 Percent Defective (or AQL=15.0 Defects per Hundred Units) [Sampling plans—AQL=15.0] Comparable sampling plans Identification letter of OC curve AA B E F H J K n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 1 0 1 3 1 2 6 2 3 9 3 4 13 4 5 21 6 7 29 7 8 L M N P Q R S n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re n c Ac Re Single 48 11 12 84 18 19 126 26 27 200 39 40 315 59 60 500 90 91 800 140 141 n c