ASTM_D_3419_-_12.pdf

Designation:D341912Standard Practice forIn-Line Screw-Injection Molding Test Specimens FromThermosetting Compounds1This standard is issued under the fixed designation D3419;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 thermosettingmaterials.It is to be used to obtain uniformity in methods ofdescribing the various steps of the injection molding processand in the reporting of those conditions.The exact moldingconditions will vary from material to material,and if notincorporated in the material specification,shall be agreed uponbetween the purchaser and the supplier or determined byprevious experience with the particular type of material beingused and its plasticity.NOTE1The utility of this practice has been demonstrated for themolding of thermosetting molding compounds exhibiting lower-viscositynon-Newtonian flow.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.3 This standard does not purport to address all of thesafety problems,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.1.4 This practice assumes the use of reciprocating screwinjection molding machines.NOTE2This standard and ISO 10724 address the same subject matter,but differ in technical content.2.Referenced Documents2.1 ASTM Standards:2D883 Terminology Relating to PlasticsD3641 Practice for Injection Molding Test Specimens ofThermoplastic Molding and Extrusion Materials2.2 ISO Standards:3ISO 10724:1994(E)PlasticsThermosetting MouldingMaterialsInjection Moulding of Multipurpose TestSpecimensISO 3167:1993,PlasticsMultipurpose Test Specimens3.Terminology3.1 Definitions:3.1.1 GeneralDefinitions of terms applying to this prac-tice appear in Terminology D883.3.1.2 injection moldingthe process of forming a materialby forcing it,in a fluid state and under pressure,through arunner system(sprue,runner,and gate(s)into the cavity of aclosed mold.3.1.2.1 DiscussionScrew-injection molding and reaction-injection molding are types of injection molding.3.2 Definitions of Terms Specific to This Standard:3.2.1 breathing,vthe operation of opening a mold or pressfor a very short period of time at an early stage in the processof cure.3.2.1.1 DiscussionBreathing allows the escape of gas orvapor from the molding material and reduces the tendency ofthick moldings to blister.3.2.2 cavity(of a mold),nthe space within a mold to befilled to form the molded product.3.2.3 landing(of a cavity),vthe practice of relieving themold around the cavity(cavities),thus reducing the surfacearea of the flat mating surfaces of the mold halves.3.2.3.1 DiscussionTypical lands are 4.5 mm(316in.)to 6mm(14in.)in width.It is recommended that landing pads beincorporated to hold the mold open 0.0125 mm(0.0005 in.)toprevent damage to the lands.4.Significance and Use4.1 This practice is subject to the definition of injectionmolding given in 3.1.2 with the further provision that within-line screw injection the plastic compound,heated in achamber by conduction and friction,is fluxed by the action of1This practice is under the jurisdiction ofASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.09 on Specimen Preparation.Current edition approved April 1,2012.Published May 2012.Originallyapproved in 1975.Last previous edition approved in 2006 as D3419-00(2006).DOI:10.1520/D3419-12.2For 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 a reciprocating screw and then is forced into a hot mold whereit solidifies.Hereafter,in-line screw-injection molding will bereferred to simply as injection molding.4.2 The mold referenced in this section(see Fig.1)isgenerally useful,and describes what have been the mostcommon specimens required for the testing of thermosets.ISOspecimens and testing are gaining favor,however.PracticeD3641 and ISO 10724 describe the layout and practice forinjection molding the multi-purpose specimens in accordancewith ISO 3167.4.3 Typically,injection-molded test specimens are madewith shorter cycles than those used