ASTM_D_3641_-_15.pdf

Designation:D364115Standard Practice forInjection Molding Test Specimens of Thermoplastic Moldingand Extrusion Materials1This standard is issued under the fixed designation D3641;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 parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This practice covers the general principles to be fol-lowed when injection molding test specimens of thermoplasticmolding and extrusion materials.This practice is to be used toobtain uniformity in methods of describing the various steps ofthe injection molding process and to set up uniform methods ofreporting these conditions.The exact conditions required toprepare suitable specimens will vary for each plastic material.Any requirements or recommendations in the material specifi-cation that differ from this standard take precedence over thosein this standard.Always consult the referenced material docu-ment for specimen preparation.If no referenced documentexists,then consult the material supplier for specimen prepa-ration guidance and note such in the test report.1.2 The methodology presented assumes the use of recipro-cating screw injection molding machines.1.3 The values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.4 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 appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.NOTE1This practice is equivalent to the following parts of ISO 294:PlasticsInjection Moulding of Test Specimens of Thermoplastic Mate-rials;294-1:Part 1General Principles and Multipurpose Test Specimens(ISO Type A Mould)and Bars(ISO Type B Mould);ISO 294-2:Part2Small Tensile Bars(ISO Type C Mould);ISO 294-3:Part 3Plates(ISO Type D Moulds).2.Referenced Documents2.1 ASTM Standards:2D256 Test Methods for Determining the Izod PendulumImpact Resistance of PlasticsD570 Test Method for Water Absorption of PlasticsD638 Test Method for Tensile Properties of PlasticsD648 Test Method for Deflection Temperature of PlasticsUnder Flexural Load in the Edgewise PositionD790 Test Methods for Flexural Properties of Unreinforcedand Reinforced Plastics and Electrical Insulating Materi-alsD883 Terminology Relating to PlasticsD955 Test Method of Measuring Shrinkage from MoldDimensions of ThermoplasticsD957 Practice for Determining Surface Temperature ofMolds for PlasticsD1525 Test Method for Vicat Softening Temperature ofPlasticsD6110 Test Method for Determining the Charpy ImpactResistance of Notched Specimens of Plastics2.2 ISO Standards:3ISO 294-1:PlasticsInjection Moulding of Test Specimensof Thermoplastic MaterialsPart 1:General Principlesand Multipurpose Test Specimens(ISO Type A Mould)and Bars(ISO Type B Mould)ISO 294-2:PlasticsInjection Moulding of Test Specimensof Thermoplastic MaterialsPart 2:Small Tensile Bars(ISO Type C Mould)ISO 294-3:PlasticsInjection Moulding of Test Specimensof Thermoplastic MaterialsPart 3:Plates(ISO Type DMoulds)ISO 20753 PlasticsTest Specimens3.Terminology3.1 DefinitionsDefinitions of terms applying to this prac-tice appear in Terminology D883.3.2 Definitions of Terms Specific to This Standard:3.2.1 average injection velocity,nthe mean value of thevelocity of the molten plastic flow front within a cavity duringthe injection time that is calculated from the shot volume andinjection time.(See Terminology D883.)1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.09 on Specimen Preparation.Current edition approved May 1,2015.Published June 2015.Originallyapproved 1991.Last previous edition approved 2014 as D3641 14.DOI:10.1520/D3641-15.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 3.2.1.1 DiscussionThe average injection velocity is calcu-lated as follows:Vav5VsTi3Ac3nwhere:Vav=average injection velocity,mm/s,Vs=shot volume,mm3,Ti=injection time,s,Ac=cross section of the cavity,mm2,(see 3.2.2)andn=number of cavities.The calculation is valid for molds containing a singlecavity or those containing identical multi-specimen cavitiesonly.This calculation does not apply for family molds.3.2.2 cross section of the cavity,nin a mold f