7 CFR 43.106 - Choosing AQL's and sampling plans.

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§ 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
1 Double plans are indicated by 2 sample sizes, n1 (first) and nt (total).Ac=Acceptance numberRe=Rejection number.
AA n1=1 01
A n1=2 01
B n1=3 01 03 12
nt=8 23
C n1=4 01 12
D n1=5 01 12
E n1=6 12 23
EE n1=7 23
F n1=9 01 12 23 34
G n1=11 12 23 34
H n1=13 01 23 34 45
J n1=21 01 02 02 23 14 34 35 45 56 67
nt=31 12 23 34 56
K n1=29 01 02 12 23 14 34 45 37 56 67 78
nt=65 12 67 9 10
L n1=48 01 02 12 23 34 45 56 67 78 89 10 11 11 12
nt=72 12
M n1=84 01 02 03 23 34 45 67 78 9 10 11 12 13 14 15 16 18 19
nt=120 12
nt=132 23
N n1=126 01 02 03 23 34 45 67 9 10 10 11 13 14 16 17 18 19 22 23 26 27
nt=180 12
nt=210 23
P n1=200 01 02 03 23 34 45 67 9 10 13 14 15 16 19 20 24 25 27 28 33 34 39 40
nt=284 12
nt=326 23
Q n1=315 01 02 0 23 34 45 67 89 13 14 19 20 22 23 28 29 35 36 41 42 50 51 59 60
nt=435 12
nt=519 23
R n1=500 02 03 23 34 45 67 9 10 12 13 18 19 28 29 33 34 42 43 53 54 62 63 76 77 90 91
nt=644 12
nt=836 23
S n1=800 03 23 34 45 67 9 10 13 14 18 19 27 28 42 43 50 510 64 65 82 83 95 96 117 118 140 141
nt=1304 23
T n1=1250 23 34 45 67 9 10 13 14 19 20 26 27 41 42 63 64 76 77
U n1=2000 34 45 67 9 10 13 14 19 20 28 29 39 40 62 63 96 97
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
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
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
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
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
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
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
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
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
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
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
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
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 315 6 7 500 9 10 800 13 14 1250 19 20 2000 28 29
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 315 8 9 500 12 13 800 18 19 1,250 26 27 2,000 39 40
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 315 13 14 500 18 19 800 27 28 1,250 41 42 2,000 62 63
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 200 13 14 315 19 20 500 28 29 800 42 43 1250 63 64 2000 96
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 200 15 16 315 22 23 500 33 34 800 50 51 1250 76 77
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 84 9 10 126 13 14 200 19 20 315 28 29 500 42 43 800 64 65
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 126 16 17 200 24 25 315 35 36 500 53 54 800 82 83
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 84 13 14 126 18 19 200 27 28 315 41 42 500 62 63 800 95 96
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 126 22 23 200 33 34 315 50 51 500 76 77 800 117 118
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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc 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
nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re nc Ac Re
nc=Cumulative sample size.Ac=Acceptance number.Re=Rejection number.
Single 48 11 12 84 18 19 126 26 27 200 39 40 315 59 60 500 90 91 800 140 141

Title 7 published on 2014-01-01

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