ASTM_D_3293_-_91a_1996_scan.pdf

l Designation:D 3293-91a(Reapproved 1996)Standard Specification for PTFE Resin Molded Sheet 1 This standard is issued under the fixed designation D 3293;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()indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.Consult the iJoD Index of Specifications and Standards for the specific year of issue which has been adopted by the Department of Defense.t.Scope l.l This specification covers molded sheet in minimum thicknesses of0.794 mm(1/32 in.)manufactured from PTFE resin molding materials.1.2 The values stated in SI units are to be regarded as the standard.The values in parentheses are for information only.1.3 The following hazard caveat pertains only to the test method portion,Section 7,of this specification:This stan-dard does not purport to address all of the safety concerns,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 limi-tations prior to use.2.Referenced Documents 2.l ASTM Standards:D 149 Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Mate-rials at Commercial Power-Frequencies:Z D 618 Practice for Conditioning Plastics and Electrical Insulating Materials for Testing3 D638 Test Method for Tensile Properties of Plastics3 D 792 Test Methods for Specifi Gravity(Relati.ve Den-sity)and DensityofPlastics by Displacemeht3 D 1457 Specification for PTFE Molding and Extrusion Materials3 D 1505 Test Method for Density af Plastics by the Density-Gradient Technique3 D 1708 Test Method for Tensile Properties of Plastics by Use of Microtensile Specimens3 D 1898 Practice for Sampling of Plastics3 D 3892 Practice for Packaging/Packing of Plastics4 E 691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method5 2.2 Military Standard:MIL-STD-105D Sampling Procedures and Tables for Inspection by Attributes6 1 This specification is under the jurisdiction of.ASTM 0:mniittee D-20 on Plastics,and is the direct responsibility 6f SubcommitteeD20.l 5 on Thermoplastic Materials(Section 20.15.12).,Current edition approved July 15,1991.Published September 1991.Originally published as D 3293-74.Last previous edition D 3293-91.2 Annual Book of ASTM Standards,Vol 10.02,3 Annual Book of ASTM Standalds,Vol 08.01.4Annual Book of ASTM Standards,Vol 08.02.5 Annual Book of ASTM Standards,Vol 14.02.6 Available from Stadardization Documents,Order Desk,Bldg.4,Section D;700 Robbins Ave.,Philadelphia,PA 19111-5094,AITN:NPODS.263 3.Classification 3.1 This specification covers the following four types of PTFE sheets:3.1.l Type I-Premium;normally used for exacting elec-trical,mechanical,or chemical applications.3.1.2 Type II-General purpose for electrical,mechan-ical,and chemical applications not requiring premium material.3.l.3 Type III-Commercial;for noncritical chemical,electrical,and mechanical applications.3.l.4 Type IV-Utility;having no electrical requirements,and with mechanical properties at a lower level.3.2 Types I,II,III,and IV may be subdivided into two grades as follows:3.2.1 Grade I-made only from virgin resin.3.2.2 Grade 2-may be made using reprocessed resin.3.3 The grades may be further subdivided into three classes as follows:3.3.l Class A-resistant to thermal dimensional change not exceeding 0.5%.,.3.2 Class B.,.resistant to thermal dimensional change not exceeding 5.0%.3.3.3 Class Cthermal dimensional change m.,iy exceed 5.0%.3.4 A one-line system may.be used to specify materials covered by this.specification.fhe system uses predefined cells to refer to specific aspeets.of this specification,as illustrated below.Specification Standard Number Block Type Grade OaM,Special.Notes Example:specuication1D 4895-89,6 c For this example,the line callout would be Specification D 4895-89,I6C,and would specify a coagulated dispersion form of polytetrafluoro-ethylene that has au of the properties listed for that Type,Grade,and Class in the appropriate specified properties,tables,or both,in the specification identified.A comma is used as the separator between the Standard Number and the Type.Separators are not needed between the Type,Grade,and C:Iass.7 Provision for Special Notes is included.so that other information can be provided when required.An example would be in Specification D 3295-81a where dimensions and tolerances are specifie 7 See the ASTM Form and Style Manual.Available from ASTM Headquarters.NOTICE:This standard has either been superseded and replaced by a new version or discontinued.Contact ASTM International(www.astm.org)for the latest information.to 3293,Q tiffi TABLE 1 Nominal Thicknesses and T