MIL-STD-1050 2 9 Apr i l 1963

--

SUPERSEDING MIL-STD-IOSC 18 July 1961

MILITARY STANDARD

SAMPLING PROCEDURES AND TABLES FOR INSPECTION BY ATTRIBUTES

MIGSTD-1OJD 29 APRIL 1963

D E P A R ~ T OF DEFENSE Washington 25, D. C,

SAMPLING PROCEDURES ANR TABLES FOR INSPETION BY ATTRIBUTES

1. T h i s s tandard has been approved by t h e Department of Defense and i s mandatory f o r use by t h e Departments o f t h e the Navy, t h e Air Force and the Defense Supply Agency. This rev i s ion supersedes MIL-STD-LO!jC, dated 18 J Q 1961.

2. 'I'lzis pub l i ca t ion provides sampling procedures and re fe rence t a b l e s f o r use . i n y h n n i n g and ~ o n d u c t i n g inspect ion by a t t r i b u t e s . T h i s publ ica t ion was developed bnj a wosking group representir ig t h e m i l i t a r y se rv ices of Canada, t h e United Kirgdorn and t h e United S t a t e s of' America with t h e a s s i s t a n c e and cooperation of h e s i c a n and Lbropean organizations f o r q u a l i t y control . The in ternat ional . designation of t h i s document i s AE-STE-105. When rev i s ion o r cance l l a t ion of thi? standard i s proposed, t h e departmental custodians w i k l inform t h e i r r e spec t ive Departmental Staridar&zation Office so t h a t appropr ia te actioab may be taken respect ing t h e i n t e r n a t i o n a l agreement concerned,

3. The U.S. Amy Munitions Cownand i s designated a s preparing a c t i v i t y f o r this standard. Recommended cor rec t ions , addi t ions , o r d e l e t i o n s should be addressed t o t h e Commanciir~g Of f l ce r , 11, S. Psmy CRR E~igineer ing Off ice , Attn: 9YII.1CGED-S, Arng Chemical Center, H a r y l a n d ,

1. 2. 3. 4. 5, 6 . 7. 8. 9.

PO. 11.

Table I Table 11-A Table 11-43 Table IZ-C Table 111-A Table 111-B Table 111-C Table !V-A Table IV-R

Table IV-C Table V-A

Table V-B

Table VI-A

Table VI-B

Table VII-.A

Table VII-B

Table VlIl Table IX

Table X-A Table #-B Table X-C

CONTENTS Page

SCOl'E 1 CLASSIFICATION OF DEFECTS AMD DEFECTIVES 2 PERCENT DEFECT1 IrE AND DSFECTS PER HUNDRED UNITS 2 ACCEPTABLE QUALITY TdEVEI, (AQL) 3 SUBMISSION OF PRODUCT 3 ACCEPTANCE AND REJECTION 4 DRAWING OF SAMPLES 4 NORMAL, TIGHTENED, AND REDUCED INSPECTION 5 SAMPLING PLANS 6 DETERMINATION O F ACCEPTABILITY 7 SUPPLEMENTARY INFORMATION 7

1 ABLE S

Sample Size Code Letters .................................................. ......... ... 9 Single Sampling Plans for Normal Inspection (Master Table) . . . 10 Single Sampling Plans for Tightened Inspection (Master Table) . 11 Single Sampling Plans for Reduced Inspection (Master Table) . . . . 12 l h u h i e Sampling Plans for Normal Inspection (Master Table) . . . 13 Double Sampling Plans for 'l'ightmed 1:lspection (Master Table) . . 14 Double Sampling Plans for Reduced Inspection (Master Table) .. 15 Multiple Sampling Plans for Normal Inspection (Master Table) .. 16 Multiple Sampling Plans for Tightened Inspection

(Master Table) .. ... ... . . . . . . . .... ..... ... ... ... .... . . . . . . . . . . : .... 18 Multiple Sampling Plans for Reduced inspection (Master Table) 20 Average Outgoing Quality Limit Factors for Normal Inspection

(Single Sampling) .. . . .. . . . . . ... . . .. . . .. . 22 Average Outgoing Quality Limit Factor for Tightened

Inspection (Single Sampling) .... .. . . . . . . . . . . . . . . . . . . . ... 23 Limiting Quality (in percent defective) for which the Pa -- 103

(for Normal Inspection, Single Sampling) . . . . . . . . . . .... . . . . . . . . .. 24 Limiting Quality (in defects per hundred units) for which the

Pa == 10'fi) (far Normal inspection, Single Sampling) . . . .. 25 Limiting Quality ( in percent defective) for which the P, -- 5 O 4 ,

(for Normal Inspection, Single Sampling) . . . . . . . . . . . . . .... . . . . . . . 26 Limiting Quality (in d ~ f r x t s per hundred units) for which

Pa = 5'x8 (for Normal Ixrspection, Single Sampling) . . . . . . . . . 27 Limit Numbers for Reduced Inspeciion . . .... . . .............. . . . . . . . . 28 Average Sample Size Curves for Double and Multiple Sampling . 29

Sampling Plans and Operating Characteristic Curves (and Data) for:

Sample Size Code Letter A . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . 30 Sample Size Code Letter I3 . . .. ......... . . . . . . . . . . . . . . . . . . . . . ........... 32 Sample Size Code Letter C .. . . ....... . . . . .. . . . . . .......... ...... .......... 34

iii

Table X-D Table X-E Table X-F Table X-G Table X-H Table X-J Table X-K Table X-L Table X-M Table X-N Table X-P Table X-Q Table X-R Table X-S

Sample Size Code Letter D .......................................................... 36 Sample Size Ccde Letter E ............................................................ 38 Sample Size Code Letter F . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Sample Size Code Letter G . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42 Sample Size Code Letter H .......................................................... 44 Sample Size Code Letter J ............................................................. 46 Sample Size Code Letter K .............................................................. 48 Sample Size Code Letter L .............................................................. 50 Sample Size Code Letter M .............................................................. 52 Sample Size Code Letter N ............................................................. 54 Sample Size Code Letter P .............................................................. 56 Sample Size Code Letter Q ................................ ' ............................ 58 Sample Size Code Letter R .............................................................. 60 Sample Size Code Letter S .............................................................. 62

INDEX OI? TERMS WITH SPECIAL MEANINGS .................................................. 63

SAMPLING PROCEDURES AND TA

FOR INSPECTION BY ATTWl

1. SCOPE

1.1 PURPOSE. This publication estab- lishes sampling plans and procedures for inspection by attributes. When specified by the responsible authority, this publication shall be referenced in the specification, con- tract, inspection instructions, or other docu- ments and the provisions set forth herein shall goverfi. The "responsible authority" shall be designated in one of the above Gocuments.

1.2 APPLICATION. Sampling plans des- ignated in this publication are applicable, but not limited, to inspection of the following:

a. End items.

b. Components and raw materials.

c. Operations.

d. Materials in process.

e. Supplies in storage.

f. Maintenance operations.

g. Data or records.

h. Administrative procedures.

The plans may also be used for the inspection of isolated lots or batches, but, nn this latter case, the user IS cautioned to cor~suHt the operating characterist~c curves to Grad a plan which will yield the desired psC~t~tltara. (see 11.6).

1.3 INSPECViO ess of measuring, ~xaminling~ testing, or otherwise cornparlng the unit of product ( s e e 1.5) with the requiremenk

I .4 INSPECT10N 5 , In- spection by attslbutes 8s mspwtion whi~r62.b~ either the unit of product IS clawffed simply as defective or rtonadefectrvc*, tar the number of defects in the unit of product is counted, with respect to a glven requnrern~itt or set of requirements

product is the thing inspected nn order to determine i t s classification as defective or nondefective or to ccmrlk the n\.trnbi.r of de- fects. It may be a single article, a pair, a set, a length, an area, an operation, a aro%eam~e~ a component of an end p rduc t , gtr the en product itself. The unit of product. may or

These plans are intended Primarily to be may not be the same as the unit of purchase. used for a continuing series of lots or batches. supply, production, or sklipmmt.

2.1 METHOD OF CLASSIFY lNG DEFECTS. A classification of defects is the enumeration of poss~ble defects of the unit of product classified accord~ng to their seriousness. A defect is any nonconformance of the unit of product wlth spec~fed riyuirements. Defects wlll normal\y be grouped into one or more of' the following classps; however, defects may be grouped mto other classes, or into subclasses w~th in these classes.

2.1.1 CRITICAL DEFECT. A critical de- fect is a defect thl; judgment and experience indicate is-likely to result in hazardous or unsafe conditions f o r individuals using, maintaining, or depending upon the product; or a defect that judgment and experience indicate is likely to prevent performance of the tactical function of a major end item such as a ship, aircraft, tank, missile or space vehicle. NOTE: For a special provision re- lating to critical defects, see 6.3.

2.1.2 MAJOR DEFECT. A major defect is a d e f e ~ t , other than critical, that is likely to result In failure, or to reduce rnater~ally the usability of the unit of product for its iiiieildi.d purpose

3. PERCENT DEFECTIVE AND

3.1 EXPRESSION OF NONCONFORM- ANCE. The extent of nonconformance of product shall be expressed either in terms of percent defective or in terms of defects p r hundred unlts.

3.2 PERCENT DEFECTIVE. The percent defective of any given quantity of units of product is one hunderd times the number of defective units of product contained therein divided by the total number of units of prod- uct, i.e.:

DEFECTS AND DEFECTIVES

2.1.3 MINOR DEFECT. A minor defect is a defect that is not ,likely to reduce ma- terially the usability of the unit of product for its intended purpose, o r is a departure from established standards having little bear- ing on the effective use or operation of the unit,

2.2 METHOD OF CLASSIIFYI TIVES, A defective is a unit of product which contains one or more defects. Defectives will usually be classified as follows:

2.2.1 CRlTllCAL DEFECTIVE. A critical defective contains one or more critical de-, fects and may also contain major and or minor defects. NOTE: For a special provi- sion relating to critical defectives, see 6.3.

2.2.2 MAJOR DEFECTIVE. A major de- fective contains one or more major defects, and may also contain minor defects but con- tains no critical defect.

2.2.3 MINOR DEFECTIVE. A minor de- fectlve contains one or rrlore minor defects b u t coniair~s 1 1 0 critical or ~x~ii jor defect.

DEFECTS PEW HQNDRED UNITS

Nunlbcr of defectives Percent defective = Number of u n ~ t s iiispwted .' 100

3.3 DEFECTS PER HUNDRED UNITS. The

number of defects per hundred units of m y

given quantity of units of product is one hundred times the number of defects con- tained therein (one or more defects being

possible In any unit of product) divided by the total number of units of product, i.e..

Defects per -.

Number of defects ' '

hundred units -. Number of units inspected r: 100

LE QUALITY LEVEL (AQL)

4.1 USE. The AQL, together with the Sample Size Code h t t e r , I S u w d for Index- ang the satnplrng plans provrded herein

E%INIT%%)N. The AQI, as the max- lmum perceiat defec.ttv~ (o r the rnaxlmerrn number of defect., pt.1 lnundr ed unlts) thdt, for purposes of sampling mspectlon, can be con=idered satacfactory as a process average (see 11 2 )

EANING OF AQL. When a Lo!istin.ir.r dc..;ignates some speclfic \ a I w of A Q L for A ccrtarn defect or group sf d ~ f e c t s , he nndlc,3te\ to thr. srzpplwr that h ~ s ( the consumer's) dcceptatncr s a m p l ~ n g plan wdl acr rp t the great malority of the lots ar batches that the supptaer submlts, pro- vided the process average level of percent defectave (o r ddcc t i per hundred units) i n

these lot., or b,iti.t~cs b t rlo greater than the designated value of AQL Thus, the AQI, 1s a designated value of percent defective (or defects per hrirzchcd u n ~ t ~ ) that the consumer 1ndlcatt.5 will be acwpted most of the time by the acceptarlcc sarnplirag plowdure to be used The sampltiig plans provided herein art? so arranged that the probab~ftty of ac- ceptance at the designated AQL value de- pend% upcn the sample m e , b a n g generally "r~gher for large sarriples than for small ones, for a given AQL The AQL alone does not

5,1 LOT OW BA The term lot or

batch shall mean "inspection lot" or "inspec-

tion batch," i.e., a collectiot~ of units of prod-

uct from which a sample is to be drawn and

inspected to determine ctrnforrnance with the

acceptability criteria, and may differ from c?

collection of units designated as a lot o r batch

describe the protection to the consumer for individual lots or batches but rni.;re directly relates to w h a t might be eupectcd from a ~ ~ i - i e s of lots or batches, provicied the ztcps irid~c~itccl in thls publication are taken It is necoss:iry to refer to the operating chai,acter- istic curve of the plan, to t1etci.rni~e v.'h3t protection the consumer will have.

4.5 SPECIFYING A Q i s . The AQI, to be used will be designat8:d the contract or by the resiwii.;ible authority, Diflerent AQLs may be d~~s ignn t t .d for g r c i i p of defects cc~n- siticreii eollcctivi.ly, or for iildividuat defects. A n h(J[, for a group o f (1cfc~t.i m a y be des- igr~;tted In addition t.o AQLs for individual defects, o r subgroups, within that 2roilp. AQI, values of 10.0 or less may be expressed either in percent defective c r in defects per hundred uni ts ; those over 10.0 shall be ex- pressed in defects per hundred uni ts only.

4.6 P R E F E R R E D AQLs. The values of AQLs given ln theie t ~ b l c s are k t l o u n as preferred AQLs I f , for a n y product, an AQL be designated other than '3 p r e f ~ r r c d AQL, these tables are not applicable

OF PRODUCT

for other purposes ( e g production, ship- ment, e tc .) .

5.2 FORMATION OF LOTS OR BATCHES. The product shall be assembled illto ~clcnti- fiable lots, sublots, batches, or In such other manner a s may be prescr~bed (see 5.4). Each lot or batch shall, as far as is practicable,

5 , SUBMISSION OF PRO UCf (Confinwe

cons~st of un~ts of product of a s~ngle type, batche~, Iot or batch size, and the manner grade, class, s~ze, and composttlon, manu- In which each lot or batch 1s to be presented factured under essent~ally the same condl- and lderltlfied by the suppl~er shall be des- tions, and at essent~ally the same t ~ m e ~ g n n t ~ d or approved by the responsible au-

thority. As necessary, the supplier shall OR BATCH 'IZE' The lot Or prowde adequate and suitable storage space

batch size is the number of units of product for each lot or batch, equipment needed for

in a lot or batch proper identification and presentation, and

5.4 P R E S E N T A T 0 N OF LOTS Of? personnel for all handling of product re- BATCHES. The formation of the lots or quired for drawing of samples.

6. ACCEPTANCE AND REJECTION

6.1 A C C E P T A B l L l T Y OF LOTS OR BATCHES. Acceptability of a lot or batch will be determined by the use of a sampling plan or plans associated with the designated AQL or AQLs.

6.2 DEFECTIVE UNITS. The right 1s re- served to reject any unit of product found defective during insphion whether that unit of product forms part of a sample or not, and whether the lot or batch as a whole is accepted or rejected. Rejected units may be repaired or corrected and resubmitted for lnspectlon with the approval of, and in the manner specified by, the responsible au- thority.

6.3 SPECIAL RESERVATION FOR CRITI- CAL DEFECTS. The supplier may be required at the discretion of the responsible authority to inspect every unit of the lot or batch for

critical defects. The right is reserved to in- spect every unit submitted by the supplier for critical defects, and to reject the lot or batch rmmediately, when a critical defect is found. The right is reserved also to sample, for crit- ical defects, every lot or batch submitted by the supplier and to reject any lot or batch if a sample drawn therefram is found to con- tain one or more critical defects.

found wcacceptable shall be r e i m v & i o n only after all

units are re-examhed or retested and ail de- fective units are removed or defects cor-

. The responsible authority shall deter- mine whether normal or tightened inspection shall be used, and whether reinspection shall include all types or classes of defects or for the particular types or classes of defects which caused initial rejection.

7. DRAWING OF SAMPLES

7.1 SAMPLE. A sample consists of one 7.2 REPRESENTATIVE SAMPLING. When or more units of product drawn from a lot or appropriate, the number of unib in the Sam- batch, the units of the sample being selected pie shall be sel in propoktion to the sizR a t random without regard to their quality. The number of units of product in the sample hes, or parts of the lot or

is the sample size. batch, identified by some rational criterion.

G OF SAMPL, 5 (Continued)

When representative saniyling is used, the ples may be drawn during assembly of thc units from each part of the lot or batch shall lot or batch. be selected at random

7.4 DOUBLE OR MULTIPLE SAMPLING. 7.3 TIME OF SAMPLING. Samples may When double or multlple sampling is to be

be drawn after ail the units comprising the used, each sample shall be selected o w r the lot or batch have been nssernbl , or sarta.. erntire lot or Batch.

EDUCED INSPECTION

8.1 INlVIATiON OF I rnal lnspection will be tired at the start of inspeictlon unless cAzerwtsc directed by the responsible authority

mal, trghtealed or reduce shall continue unci-inraged fox each class of defects or defectrves on sucressiw 'tots or b a t c h except whwe the swit ihi dures given below require dh

a. The preceding 10 lots or batches (or more, as indicated by the n o k to Table VIII) have been on normal inspection and none has been rejected on original inspection; and

b. The total number af defectives (or de- fects) in the samples from the preceding 10 lots or batches (or such other number as was

for condition "a" above) is equal to or less than the applicable number given in 'V'able VIII. If double or multiple sampling is in use, all samples inspected should be in- cluded, not ''fimt" samples only; and

switching procedurc-i given1 below rsquire a c. ~ roduc t ion is a t a steady rate; and

change. The switchmg procedures shall be applied to ~ a c h class of deiccts or .dea'e?-tives, d . Reduced ~nspection is considered de- independently. sirable by the responsible authority.

8.31-4 REDUCED TO NORMAL. When re- duced inspection is in effect, normal inspee-

8.3.1 NORMAL 7 0 SiG"fENiD, Nhen t::~i Aa!! be :i;stiti;td if m y of the following occur on orlgmal inspection. normal inspectmn 1s In eflecf trghtened i n -

spectnon shall be instituted w2wn 2 d 5 a A lot or batch is rejected; or consecutive lots or hatches have been re- h. A lot or batch is considered acceptable jected on original inspection ( i . c . , ignoring tinder the procedures of 10.1.4; or resubmitted lots or batches for this proce- c . Production becomes irregular or de- dure). layed; or

8.3.2 TIGHTENED TO NOR d Other cond~tmns warrant that normal tightened ~nspcctrun is effect, iiorrn,d In- inspection be jnstituted. spection shall b~ lns t~ tu ted whesi 5 consecu- ONTlMLlATlON OF INSPECTION. tive lots or batches have h e n c a r ~ s d c r d 1, t that 10 consecutive lots or acceptable on orr~nnal an batches remam on tightened inspection (or

tion shall be instituted provldrng that all of dljcontinued wnding action to improve the the foHowing conditions are ~ a t ~ f i e ( i i qua!ity of submitted material.

9.1 OANaPtlNG PUN. A sampling plan indicates the number of units of product from each lot or batch which are to be in- spected (sample size or series of sample

e criteria for determining the , acceptabifity of the lot or batch (acceptance

and rejection numbers).

9.2 lNSPECliON LEVEL. level determines the relationship between the lot or batch size and the sample size. The inspectian level to be used for requirement will be prescrib spohsible authority. Three inspection levek: I, JJ, and 111, are given in Table I for general &. Unless otherwise specified9 Inspection

us&. However, I n s p c t i ~ n pecified when less discrimi-

nation is needed, or k v e l 11% may be speci- fied for greater discri~ination. Four addi- tional special levels: S-1, S-2, are given in the same table and may be us where relatively small sample sizes are neces-

rge sampling risks can or must kae

In the d~ igna t ion of inspmtion levels S-1 to S-4, care must be exereis

inconsistent with thew inspec-

E M . Sample sizes are designated by code letters. Table I shall be used to find the applicable code letter for the particular lot or batch size and the prescribed inspection level.

OBTAittllNG SAMPLlhsG P the code letter shall be

the tables direct the user Bei a different letter. e sample size to be used is given by the

new code letter nut by the ori this procedure leads t for different classes n

corresponding to the may be used for all classes of defects

when designated or approve

sible authority. As an alterna sampling plan with an acee of 0, the plan with an aeseptsance number af P with its corsesp for a $esignated

responsible authority.

double or mdtiple.

16. DETEIRMINATIIBM OF ACCEPTABILITY

K E N T DEFECTIVE INSPECTION. number of defectives found in the first and e acceptability of a lot or batch second samples shall be accumulated. If the

ptrcent defective inspection, the ap- cumulative number of defectives is equal to piicablc sampling plan shall be used in or less than the second acceptance number, pcc0rd.n~ with 10 1.1, 10 1.2, 10,1.3, 10.1.4, the lot or batch shall be considered accept- and 10.1.5. able. If the cumulative number of defectives

is equal to or greater than the second rejec-

PLING PUN. The tion number, the lot or batch shall be rejected.

number of sample units inspected shall be equal to the sample size given 'by the plan 10.1.3 MULTIPLE SAMPLE PUN. Under

If the number of defectives found in the multiple barn~ling, the procedure shall be

sample is equal to or less than the acceptarae similar to that specified in 10.1.2, except that

number, the lot or batch shall be considered the number of successive samples required acceptable. If the number of defectives is to reach a decision may be more than two.

equal t~ or greater than the rejection num- ber, the lot or batch shall be rejected.

10.1.1 DCSUBLIE SAMPLlDdG $!AN. The number of sample units inspected shall be equal to the first sample size given by the plan. If the number of defectives found in the first sample is equal to or less than the &st acceptance number, the lot or batch dJ1 be camisidlered acceptable If the num- ber ef Bafectives found in the first sample is equal to or greater than the First rejection wudme, L!! !d or batch shall be reject&. If the number of defectives found in the first #mplc: ir between the first acceptance and rejection numbers, a smwd sample of the aize given by the plan shall be inspected. The

10,1.4 S P E C I A L PROCEDURE FOR RE- DUCED INSPECTION. Under reduced in- spection, the sampling procedure may termi- nate without either acceptance or rejection criteria having been met. In these circum- stances, the lot or batch will be considered acceptable, but normal inspection will be reinstated starting with the next lot or batch ( see 8.3.4 ( b ) ) .

2 DEFECTS PER HUNDRED UNITS IN- SPECTION. To determine the acceptability sf a 1st or batch under Deiecis per Hundred Units inspection, the procedure specified for Percent Defective inspection above shall be used, except that the word "defects" shall be substituted for "defectives."

1 I . SUPPLEMENTARY t NFQRMAf ION

11.1 Q P t R A T l W O CHARACTERISTIC CURVES. The opmhg characteristic curves for normal inspectian, shown in Table X (~ryr 30-62), indicate the percentage of h a a batches which may Bc cxpactcd to be

under the vorioue sampling plans kr r process quality. Tht cuwes shown

LIB

and multiple sampling are matched as closely as practicable. The 0. C. curves shown for AQLs greater than 10.0 are based on the Poisson distribution and are applkablt for defects per hundred units .inspection; those for AQLs of 10 0 or less and sample sizcr of 80 or less are based on the binomial distri- bution and are applicable for percent defec-

tivs jnspwtion; those for AQLS of 10.0 or less nand sample sizes larger then 80 are based on the Porsson distribution and are applica- ble eitiber for defects per heandled units in-

ction, or for percent defective inspection Poisson distribution being an adequate oxmation to the binomial distribution

under these conditions). 'T'abulated values, corresponding to selected values of probabil- ities of acceptance (Pa, in percent) are given for each of the rves shown, and, in addi- tion, for tighten mspction, and for defects

r6d units for sample sizes of 62.0 o

AGE. The process erccnt defective or

per hundred units of product sub-

r original inspec- the first inspec-

tion 0% a psrtic-en%ar quaantiby of product as islaed horn the i~rspcvtion of p rduct

e m resubmitted after prior rejwGnaa,

eluding all accepted lots all rejected lots or batches

ts or batches have been

AOQL is the maximum ossible incoming quali-

r a given accepbmee s a m p h g plan. vfnXues are given in Table V-A for

11.5 AVERAGE SAMPLE SIZS CURVES. Average sample size curves for double and multiple sampling are in Table IX. These show the average sample sizes which may be expected to occur under the various sampling plans for a given pimess quality. The curves assume r:o curtailment of inspection and are approximate to the extent that they are based upon the Poisson distribution, and that the sample sizes for double and multiple sampling are assumed to be 0.631n and 0.25n respectively, where n is the equivalent single sample size.

1 1.6 LIMITING QUALITY PROTECTION. The sampling plans and associated proce- dures given in this publication were designed for use where the units of product are pro- duced in a continuing series of lots or batches over a period of time. However, if the lot or batch is of an isolated nature, it is desira- ble to limit the selection of sampling plans to those, associated with a designated AQL value, that provide not l e s than a specified limiting quality protection. Sampling plans for this purpose can be selected by choosing a Limiting Quality (LQ) and a consumer's risk to be associated with it. Tables VI and VII give vaIues of LQ for the commonly used consumer's risks of 10 percent and 5 percent respectively. If a different value of con- sumer's risk is required, the O.C. curves and their tabulated values may be used. The concept of LQ may also be useful in specify- ing the AQL and 1nsp&tion Levels for a series of lots or batches, thus fixing minimum sample size where there is some reason for avoiding (with more than a given consumer's risk) more than a limiting proportion of de- fectives (or defect) in any single lot or batch.

LEMENTARY INFORMATION (Continued)

8

4 u e 4 m m m m u u u u o o o

. - - ......... .... * a -

", , , ; * ;I+ ... .............. m e " ? , m * . , ,

.4 ... c4

NORMAL

SINGLE REDUCED

MULTIPLE

NORMAL 22

Acceptable Ouality Ltve l

TABLE VII-A-Limiting Q w l i t p v (in percent defective) for which Pa = 5 Percent (for NCW& Inspection, Single rampling)

(See 11.6)

TABLE Vl11- Limit Numberr for Redwad IuspSrtk

( S n 8.3.3)

AVERAGE SAMPLE SIZE

TABU X-&;? - SAhWLlNG PUNS FOR SAMPLE SIZE CODE LmER: B

7 7

TABLE X-D-Tabies for romple size code letter: D

CMRT D - WlRATJNG CHARACTERISTIC CURVES FOR SINGLE SAMPLING PLANS t b - br&b d dtlpl . diq .I u c b d y Y p&.blrl

TABLE X-Dl - TABULATED VALUE!; FOR OPERATING CHARACTERISTIC CURMS F(R SINCLE SAMPLING PUNS

TABLE .X-H-Tables for mrnple sue sods letter: H

TABU X-KI - TABULATED VALUES FOR WERATING CHARACTERISTIC CURVES FOR SINGLE SAMPLING PUNS

TABLE .X-K-Tabks for sample size code letter: K

TABLE X-K-I - TABUUTED VALUES FOR WERATING CHARACTERISTIC CURVES FOR SINGLE SAMPLING PLANS

I

Index of terms with special meaninys

T e r m Paragraph

Acceptable Quality Level (AQL) . . . . ~. ~ 4 2 and 111 9 4 and 10.1 1

. . '33

Defects per hundred units

Limiting Quahty (LQ)

Minor defective

Preferred AQLs ~ . . . . ~ . . .. . 4 6

8 2 a n d 8 .3 .3

Switching procedures . . . . . . .

Tightened inspection . . ~ 8.2 anri 3 2.1 Unit of product ~ . . 1.5

Copies of t h i s standard m a y be obtained by d i r e c t i n g reques t s tot

Commanding Off ice r U.S. Naval Supply Depot A'ITN: Code LIKE 5801 Tabor Avenue Phi ladelphia 29, Pennsylvania

Copies of t h i s M i l i t a i y Standard m a y be obtained f o r o the r than o f f i c i a l use by individuals , firms, and con t rac to rs from t h e Superintendent of Documents, U.S. Government P r i n t i n g Office, Washington 25, D. C.

Both t h e t i t l e and identifying symbol number should be s t i p u l a t e d when requesting copies of Mi l i t a ry Standards.

Custodians :

Army - Munitions Command Navy - Bureau of Wea-pns Air Force - Air Force Logis t i c s Command Defense Supply Agency

P r e p a r h g Activity:

Army - Munitions Command

7iU.S. GOVERNMENT PRlNTING OFFICE: 1980-603-12 114090

A M E O F ORGANl lAT iON AND &DORE55 CONTRACTNUMWER

MATERIAL PROCURED UNDER A - a OIRECT G O V E R N M E N T C O N T R A C T r: S U U i o l i ~ i i ~ ~

H A S ANY Pi \ f iT O F T H E DOCUMENT CREATED PROBLEMS OR REQUIRED INTERPRETATION I N PRO== U S E ?

- CQMMLNTS ON A N Y DOClJMF.N7 R E U U ~ R E M E N T CONSIDERED TOO RIGCD

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