1、Designation:D256294(Reapproved 2015)Standard Practice forClassifying Visual Defects in Parts Molded from ReinforcedThermosetting Plastics1This standard is issued under the fixed designation D2562;the number immediately following the designation indicates the year oforiginal adoption or,in the case o
2、f revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This practice covers acceptance criteria for visual in-spection of parts molded from reinforced ther
3、mosetting plasticsby compression and transfer molding.1.2 This practice presents word descriptions of possibledefects to serve as a guide for contracts,drawings,productspecifications,and final inspection.1.3 This practice also categorizes different inspection re-quirements for grades of product qual
4、ity.1.4 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish app
5、ro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1There is no known ISO equivalent to this standard.2.Acceptance Criteria2.1 The method and frequency of sampling and the allow-able defects may be previously agreed to by the purchaser a
6、ndthe seller.2.2 Dimensions and TolerancesMolded parts shall beinspected for conformance with the dimensions and tolerancesspecified on the product drawing.Parts with any dimensionsfalling outside the specified limits shall be rejected.2.3 InsertsAll inserts,nuts,studs,and lugs shall not bedamaged i
7、n any way,nor coated with molding materials insuch a way as to impair function or mechanical fit.Threads inmolded-in inserts shall be clean,smooth,and free of nicks,tears,or other damage.There shall be no molding material orflash on the threads.If necessary,threaded inserts may beretapped to clean t
8、hem or remove flash.Threads containinglocking features may not be retapped.2.4 Molded-In Threads or Cored HolesMolded-in threadsor cored holes shall be free of visible defects,such as nicks,cracks,shorts,etc.Molded-in threads may be retapped orrepaired unless otherwise specifically noted on the prod
9、uctdrawing.2.5 WorkmanshipWorkmanship shall be in accordancewith good commercial practices.2.6 Critical AreasAreas in which the presence of imper-fections is considered to be detrimental to the proper functionof the part shall be designated as critical areas.The areas of apart that are critical stru
10、cturally,aerodynamically,or electri-cally shall be uniform and free of defects as listed in Table 1,if so stated on the product drawing.Critical areas may bedesignated on the product drawing by one of the followingmeans,2.6.1 Encircle critical areas,or2.6.2 Cross-hatch areas to designate areas of va
11、rious levels,or2.6.3 Word description.2.7 Acceptable DefectsUnless otherwise specified,thefollowing defects shall be acceptable in all instances:2.7.1 Ripple SurfaceGenerally occurs in parts moldedfrom long,glass-fiber-filled,high-impact-type plastics.Such asurface is a phenomenon resulting from the
12、 difference inshrinkage between the resin binder and reinforcement.2.7.2 Shrink-MarkA dimple-like depression in the surfaceof a molding where it has retracted from the mold,and whichhas well-rounded edges.A shrink-mark generally occurs onone surface of a part where there is a boss,flange,rib,or othe
13、rheavy section on the opposite surface.The shrink-mark may becaused by the difference in total shrinkage when there is asudden change in section along the surface of the part.2.7.3 Resin VoidsApplicable to chopped fabric-reinforcedmolding compounds only,appearing as multiple surface inter-ruptions w
14、hich conform to the pattern of the cloth weave.Thisis usually due to an insufficient flow or shrinkage of the resin,which fails to fill all of the interstices of the fabric reinforce-ment.These defects occur only at the surface layer of resin incontact with the mold.1This practice is under the juris
15、diction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.18 on Reinforced ThermosettingPlastics.Current edition approved.Published September 2015.Originally approved in1966.Last previous edition approved in 2008 as D2562 94(2008).DOI:10.1520/D2562-94R15.Copyright
16、ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.7.4 Surface DiscolorationAn apparent nonuniformity ofa material,evidenced by the appearance of dark streaks.Surface streaks are frequently caused by incorporation into theplastic of ejector pin lubricant,mold release,or metallic matterabraded from ejector pins.2.7.5 Weld-or Knit-LinesMarks on,or weaknesses in,amolded plastic,formed by the union of two or more streams ofplastic flowing together,t