ASTM D3777-97

Standard Practice for Writing Specifications for Textiles

SCOPE
1.1 This practice covers general methods for specifying textile product characteristics that may be measured or counted.
1.2 There are many different types of acceptance samplings plans. This practice describes five types. (See 1.5.)
1.3 This practice describes general methods for writing the sampling plans of the types named in 1.5 whose characteristics may be measured or counted. The requirements are described in terms of what the basic unit is and what limit constitutes a nonconforming item. Tables are provided from which appropriate sampling plans can be designed. Numerical examples illustrate the design of sampling plans and the construction of their consequent operating characteristic curves.
1.3 This standard does not purport to address all of the safety problems, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.  
1.4 This practice includes the following sections:  Section Scope 1 Referenced Documents 2 Terminology 3 Significance and Use 4 Organizational Form for Specifications 5 Introductory Sections 6 Requirements Section 7 Sampling 8 Test Methods 9 Sampling Plans 10 Operating Characteristic Curve 11 Keywords 12
1.5 The annexes include:  Topic Title Annex Number Types of Sampling Plans: Single-Sample Fraction-Nonconforming Attribute Data A1 Single-Sample Nonconformances-per-Unit A2 Single-Sample by Variables to Control Fraction-Noncon- A3 forming with Standard Deviation Known Single-Sample by Variables to Control Fraction-Noncon- A4 forming with Standard Deviation Unknown Chain Sampling A5

General Information

• Status: Historical
• Publication Date: 09-Sep-1997
• Technical Committee: D13 - Textiles

Relations

• Replaced By: ASTM D3777-97(2002) - Standard Practice for Writing Specifications for Textiles (Withdrawn 2008)
• Effective Date: 10-Sep-1997

Standards Content (Sample)

NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3777 – 97
Standard Practice for
Writing Specifications for Textiles
This standard is issued under the fixed designation D 3777; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice covers general methods for specifying 2.1 ASTM Standards:
textile product characteristics that may be measured or D 123 Terminology Relating to Textiles
counted. D 2906 Practice for Statements on Precision and Bias for
1.2 There are many different types of acceptance samplings Textiles
plans. This practice describes five types. (See 1.5.) D 4271 Practice for Writing Statements on Sampling in Test
1.3 This practice describes general methods for writing the Methods for Textiles
sampling plans of the types named in 1.5 whose characteristics 2.2 Adjunct
may be measured or counted. The requirements are described TEX-PAC
in terms of what the basic unit is and what limit constitutes a
NOTE 1—Tex-Pac is a group of PC programs on floppy disks, available
nonconforming item. Tables are provided from which appro-
through ASTM Headquarters, 100 Barr Harbor Drive, West Consho-
priate sampling plans can be designed. Numerical examples
hocken, PA 19428, USA. The points on the operating characteristic (OC)
illustrate the design of sampling plans and the construction of curves described in the Annexes of this Standard can be calculated using
programs in this adjunct.
their consequent operating characteristic curves.
1.4 This standard does not purport to address all of the
2.3 Other Standards:
safety concerns, if any, associated with its use. It is the
ANSI/ASQC Z1.4 Sampling Procedures and Tables for
responsibility of the user of this standard to establish appro-
Inspection by Attributes
priate safety and health practices and determine the applica-
MIL-STD-105D Sampling Procedures and Tables for In-
bility of regulatory limitations prior to use.
spection by Attributes
1.5 This practice includes the following sections:
MIL-STD-414 Sampling Procedures and Tables for Inspec-
Section
tion by Variables by Percent Defective
Scope 1
Tables of the Binomial Probability Frequency Distribution
Referenced Documents 2
(No. 6 Of the Applied Mathematics Series), National
Terminology 3
Significance and Use 4
Institute of Standards and Technology (NIST)
Organizational Form for Specifications 5
Introductory Sections 6
3. Terminology
Requirements Section 7
Sampling 8
3.1 Definitions:
Test Methods 9
3.1.1 acceptable quality level, (AQL or p ), n—in accep-
Sampling Plans 10
tance sampling, the maximum fraction of nonconforming items
Operating Characteristic Curve 11
Keywords 12
at which the process average can be considered satisfactory;
the process average at which the risk of rejection is called the
1.6 The annexes include:
producer’s risk.
Topic Title Annex Number
3.1.2 acceptance number, (c), n—in acceptance sampling,
Types of Sampling Plans:
Single-Sample Fraction-Nonconforming Attribute Annex A1
the maximum for the number of nonconforming items in a
Data
sample that allows the conclusion that the lot conforms to the
Single-Sample Nonconformances-per-Unit Annex A2
Single-Sample by Variables to Control Fraction-Non- Annex A3 specification.
conforming with Standard Deviation Known
Single-Sample by Variables to Control Fraction-Non- Annex A4
conforming with Standard Deviation Unknown
Annual Book of ASTM Standards, Vol 07.01.
Chain Sampling Annex A5 3
Annual Book of ASTM Standards, Vol 07.02.
PC programs on floppy disks are available through ASTM. For 3 ⁄2 inch disk
request PCN:12-429040-18, for a 5 ⁄4 inch disk request PCN:12-429041-18.
American Society for Quality Control, 230 West Wells Street, Milwaukee, WI
53203.
This practice is under the jurisdiction of ASTM Committee D-13 on Textiles
Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700
and is the direct responsibility of Subcommittee D13.93 on Statistics.
Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.
Current edition approved Sept. 10, 1997. Published August 1998. Originally
Available from National Institute of Standards and Technology, NIST, Gaith-
published as D 3777 – 79. Last previous edition D 3777 – 91.
ersburg, MD 20899.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3777
3.1.3 acceptance sampling, n—sampling done to provide sampling plan where the size of the lot being sampled is taken
specimens for acceptance testing. into consideration.
3.1.21 type B operating characteristic curve, n—an operat-
3.1.4 acceptance testing, n—testing done to decide if a
material meets acceptance criteria. ing characteristic curve which describes the operation of a
sampling plan where items are drawn at random from a
3.1.5 chain sampling, n—in acceptance sampling, a sam-
theoretically infinite process.
pling plan for which the decision to accept or reject a lot is
3.1.22 For definitions of textile and statistical terms used in
based in part on the results of inspection of the lot and in part
this practice refer to Terminology D 123.
on the results of inspection of the immediately preceding lots.
3.1.6 consumer’s risk, (b), n—in acceptance sampling, the
4. Significance and Use
probability of accepting a lot when the process average is at the
4.1 All purchase agreements should be based on a specifi-
limiting quality level.
cation of the material to be purchased which is agreeable to
3.1.7 laboratory sample, n—a portion of material taken to
both parties. The parties should have a common understanding
represent the lot sample, or the original material, and used in
of the quality of material described by the specification. This
the laboratory as a source of test specimens.
practice describes how to write such a specification.
3.1.8 limiting quality level, (LQL or p ), n—in acceptance
4.2 All purchase agreements should contain a sampling plan
sampling, the fraction of nonconforming items at which the
to use to determine the disposition of lots of material. A
process average can be considered barely tolerable; the process
specification is not complete without a sampling plan. This
average at which the risk of acceptance is called the consum-
practice describes how to write sampling plans which, when
er’s risk. (Syn. lot tolerance fraction nonconforming.)
used as part of a purchase agreement, will give the parties a
3.1.9 lot, n—in acceptance sampling, that part of a consign-
common understanding of the quality of material described, the
ment or shipment consisting of material from one production
risks connected with the sampling and testing procedures, and
lot.
the procedures to follow when a lot is rejected.
3.1.10 lot tolerance fraction nonconforming, n—see limit-
4.3 It should be clearly understood that no sampling plan,
ing quality level.
including 100 % inspection, can make certain that all accepted
3.1.11 nonconforming, adj—a description of a unit or a
lots will have a certain quality. No matter what the quality level
group of units that does not meet the unit or group tolerance.
a vendor supplies, if the purchaser continues to receive
3.1.12 nonconformity, n—an occurrence of failing to satisfy
shipments from the same vendor, a portion of the shipments
the requirements of the applicable specification; a condition
will be accepted by the sampling plan. All a sampling plan can
that results in a nonconforming item.
do is increase the probability of acceptance of good lots, and
3.1.13 operating characteristic curve, OC-curve, n—in ac-
decrease the probability of acceptance of bad lots.
ceptance sampling, the curve which has as its abscissa an
4.4 When inspection is inexpensive and not destructive, or
hypothesized lot average, and which has as its ordinate the
when it is extremely important that all nonconforming items be
probability of accepting the lot, when the plan is used. (See
detected, conformance to the specification may be determined
also type A operating characteristic curve and type B operating
by complete inspection of every item in the lot.
characteristic curve.)
4.5 When neither of the situations described in 4.4 pertain,
3.1.14 producer’s risk, (a), n—the probability of rejecting a
a sampling plan which involves less than 100 % inspection
lot when the process average is at the acceptable quality level,
may be used. A plan should be chosen which will divide the
the AQL.
cost of imperfect judgments caused by inspecting only a
3.1.15 rejection number, n—in acceptance sampling, the
portion of the lot between producer and buyer. This practice
minimum number of nonconforming items in a sample that
describes some simple methods for preparing sampling plans.
requires the conclusion that the lot does not conform to the
More complex sampling plans may be justified when the costs
specification. 8,9
of inspection are high. Such plans may be found in Duncan,
3.1.16 sample, n—(1) a portion of a lot of material which is
MIL-STD-105D, and in MIL-STD-414. In any case, sampling
taken for testing or for record purposes; (2) a group of
plans can be compared using their operating characteristic
specimens used, or observations made, which provide infor-
curves and their costs.
mation that can be used for making statistical inferences about
4.6 The operating characteristic curves in this practice are of
the population(s) from which they were drawn.
the type B. That is, that the lots being inspected are assumed to
3.1.17 sampling unit, n—an identifiable discrete unit or
be infinitely large. This assumption is convenient, and no
subunit of material that could be taken as part of a sample.
significant error is introduced, if the lot size is 1000 or more
3.1.18 single sampling, n—in acceptance sampling, a sam-
items, or if the sample size is no more than 10 % of the lot size.
pling plan for which the decision to accept or reject a lot is
In other cases the consumer’s risk will be somewhat over-
based on a single sample.
stated.
3.1.19 specification, n—a precise statement of a set of
requirements to be satisfied by a material, product, system, or
Duncan, Acheson J., Quality Control and Industrial Statistics, Richard D.
service, that indicates the procedures for determining whether
Irwin, Inc., Homewood, IL, 1974.
each of the requirements is satisfied.
Hahn, Gerald J., Schilling, Edward G., “An Introduction to the MIL-STD-105D
3.1.20 type A operating characteristic curve, n—an operat-
Acceptance Sampling Scheme,” Standardization News, American Society for
ing characteristic curve which describes the operation of a Testing and Materials, September 1975, pp. 20–26.
NOTICE: This standard has either been superceded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
D 3777
A
TABLE 1 Requirements of Acceptance Criteria
listed in the section on referenced documents. If it is necessary
Requirement Test Method Lot Acceptance Criteria to make minor changes in the test method, add a section on
No separation of components D XXXX accept if nonconforming units
precision and bias as follows: “The precision and bias of this
< 2 in sample of 36 units
test method are not changed significantly by the minor changes
¯
Tenacity, min 5 1200 mN/tex D YYY accept if X > 1779.9 mN/tex,
s8 5 324 for sample of 22 items specified above.” (See Practice D 2906.)
A
¯
X 5 observed average. 9.2.2 If the less desirable option of writing a test method
within the specification is used, the test method cannot be
TABLE 2 Basis for Acceptance Sampling Plan referenced in another specification. In addition, the test method
must include sections on scope, significance and use, proce-
Fraction of Lot Out of
Risk Factors
Specification
dure, and precision and bias as required by Part A of Form and
Property Acceptable Limiting 10
Pro- Con- Style for ASTM Standards. For practical purposes, this option
Quality Quality
ducer’s sumer’s
is no easier than writing a separate test method and contains
Level Level
Component separation 0.01 0.11 0.05 0.10
serious drawbacks.
Tenacity 0.015 0.07 0.04 0.075
9.3 If neither a measurement nor a count can be made on a
unit of the sample, state in writing what is to be done and how
conformance is to be decided. If appropriate, specify that
5. Organizational Form for Specifications
physical samples of satisfactory and unsatisfactory materials
5.1 The important parts of a specification are: designation
are to be exchanged by the producer and the buyer.
number, title, scope, reference documents, terminology, re-
9.4 In case of a dispute arising from differences in reported
quirements, sampling plan, test methods, and operating char-
test results follow the procedure described in the applicable test
acteristic curve. See Part B of Form and Style for ASTM
method.
Standards for further information regarding parts and their
order of presentation.
10. Sampling Plans
10.1 Single-Sample Fraction-Nonconforming Attribute
6. Introductory Sections of Specifications
Data—Attribute inspections are summarized in terms of frac-
6.1 Write the sections on title, scope, referenced documents,
tion of units not conforming. Simple two-point plans are based
and terminology in accordance with Form and Style for ASTM
on two selected points on the operating characteristic curve.
Standards.
Single-sample plans base the decision to accept or reject the lot
being sampled on one sample only. The plans in this standard
7. Requirements Section of Specification
are based on the binomial frequency distribution. They do not
7.1 State the requirements for a laboratory sampling unit.
take into account inspections made on prior lots from the same
Requirements may be expressed as attributes or as variables.
vendor. The calculation of such plans is described in Annex A1.
Tolerances may be one-sided or two-sided. It is recommended
10.2 Single-Sample Nonconformances-Per-Item—A single-
that the sections specifying the requirements are preceded by a
sample nonconformance-per-unit plan consists of one sample
center heading reading Requirements.
of size n and an acceptance number c. If the sample has a total
7.2 Table 1 illustrates the requirements and acceptance
number of instances of nonconformances less than or equal to
criteria for an attribute and a variables plan. This table is based
c, ac
...