1、Designation:D 1898 68(Reapproved 1989)Standard Practice forSampling of Plastics1This standard is issued under the fixed designation D 1898;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parenthe
2、ses indicates the year of last reapproval.Asuperscript epsilon(e)indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.Scope1.1 This practice is primarily a statement of principles toguide purchasers of
3、plastic materials purchased under specifi-cations to prepare sampling plans that will describe samplingprocedures and that will enable them to determine withinpractical limits whether or not the products meet the specifi-cations.1.2 The same principles may be used to guide the prepara-tion of specif
4、ications in quantitative terms.1.3 Some of the same principles may be used to determinethe actual quality of a product,including its average andvariation above and below that average,with respect to aparticular property.1.4 Since the design of probability sampling depends uponthe ultimate use of the
5、 samples and the resulting data,consid-eration must be given to the intended inspection of the samples.Hence,the design of plans for examination and testing ofsamples for both their attributes and their variables is included.1.5 This practice is intended for general guidance whenlittle information i
6、s available on the variability of the materialand of the method of inspection.In some cases,quality controlchart methods may be substituted for the procedures herein.Inany event,a statistician should be consulted if difficulty isencountered in applying the recommendations herein to thedesign of a sp
7、ecific sampling problem.1.6 There is no intent to guide the disposition of materialthat is found to be off-specification by sampling and inspection;disposition is a contractual matter.1.7 The following outline is presented to facilitate use ofthis practice:SectionGeneral Philosophy4Sampling of Attri
8、butes5Sampling for Variables6Means and Standard Deviations7Comparison of Sampling Plans8Sampling Procedures:General9 to 11Random10Stratified11Specific12 to 15Apendixes:GlossaryX1Inspection by AttributesX2Inspection by VariablesX3Example of Use of Previous Data for Judging theQualities of Lots and fo
9、r Setting SpecificationLimitsX41.8 The values stated in SI units are to be regarded as thestandard.1.9 This standard may involve hazardous materials,opera-tions,and equipment.This standard does not purport toaddress all of the safety problems associated with its use.It isthe responsibility of the us
10、er of this standard to establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:E 122 Practice for Choice of Sample Size to Estimate theAverage Quality of a Lot or Process22.2Military Standards:3MI
11、L-STD-105 Sampling Procedures and Tables for Inspec-tion by AttributesMIL-STD-414 Sampling Procedures and Tables for Inspec-tion by Variables for Percent Defective3.Significance and Use3.1 The purpose of the sample may be as follows:3.1.1 To estimate properties of a lot or shipment,such as thepercen
12、tage of some constituent,the fraction of the items thatfail to meet a specific requirement,the average weight orproperty of an item,or the quality or total weight of theshipment,or simple identity.3.1.2 To dispose of the lot or shipment rationally,withoutthe intermediate step of the formation of an
13、estimate.3.1.3 To define new materials in terms of their properties.3.1.4 To provide material for evaluation of a test method.4.General Philosophy4.1 Sampling is a means employed to meet the problem ofestimating the quality of a lot from the inspection of only part1This practice is under the jurisdi
14、ction of ASTM Committee D-20 on Plasticsand is the direct responsibility of Subcommittee D20.13 on Statistical Techniques.Current edition approved Jan.10,1968.Published March 1968.Originallypublished as D 1898 61 T.Last previous edition D 1898 61 T.2Annual Book of ASTM Standard,Vol 14.02.3Available
15、from Standardization Documents Order Desk,Bldg.4 Section D,700Robbins Ave.,Philadelphia,PA 19111-5094,Attn:NPODS.1AMERICAN SOCIETY FOR TESTING AND MATERIALS100 Barr Harbor Dr.,West Conshohocken,PA 19428Reprinted from the Annual Book of ASTM Standards.Copyright ASTMNOTICE:This standard has either bee
16、n superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.of the lot.When 100%inspection(“screening”)of a lot isperformed,sampling does not apply.4.2 The inspection of the sample or portion according to asampling plan results in an estimation of properties,hence,anuncertainty which can be expressed for a given sampling planin terms of an operating characteristic curve.Each such curve,that is,for a given acceptable quality level,
