ASTM_D_958_-_88_scan.pdf

ASTM Dy58 88 m 0757530 0040403 9 m SiTb Designation:D 958-88 AMERICAN SOCIETY FOR TESTING AND MATERIALS 1916 Race St.,Philadelphia,Pa.19103 Reprinted from the Annual Eook of ASTM Standards.Copyright ASTM If not listed in the current combined index,viill appear in the next edition.Standard Practice for Determining Temperatures of Standard ASTM Molds for Test Specimens of Plastics This standard is issued under the fixed designation D 958;the number immediately foliowing 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(E)indicafes an editorial change since the last revision or reapproval.1.Scope PROCEDURE USING THERMOMETER 1.1 This practice covers two optional procedures for determining the temperature condition of standard ASTM molds for test specimens of plastics by means of either a thermometer or a pyrometer.1.2 The values stated in SI units are to be regarded as the standard.The values in parentheses are given for informa-tion only.1.3 This standard may involve hazardous materials,oper-ations,and equipment.This standard does not purport to address all o f the safety problems associated with its use.It is the responsibility o f the user o f this standard to establish appropriate safety and health practices and determine the applicability o f regulatory limitations prior to use.2.Referenced Documents 2.1 ASTM Standards:D 647 Practice for Design of Molds for Test Specimens of Plastic Molding Materials2 D 957 Practice for Determining Mold Surface Tempera-ture of Commercial Molds for Plastics2 E 1 Specification for ASTM Thermometers3 3.Significance and Use 3.1 The properties of molded parts and the ease of producing satisfactory specimens are influenced by the temperature of the mold.It is desirable to know the actual mold temperature which may be different from the mold temperature control medium.3.2 The user should be aware of temperature differences across the mold/thermocouple interface and at leads and should take precautions to minimize such differences.4.Molds 4.1 Requirements for the design of standard ASTM molds for test specimens of plastics are covered by Practice D 647.5.Apparatus 5.1 Thermometer-A 76-mm(3411.)immersion,mer-cury-filled thermometer having a temperature scale of not more than 25C(45F)per 25 mm(1 in.)of length shall be used.NOTE I-The following ASTM standard thermometers(see Specifi-cation E I)are considered satisfactory:95C,96C,IOOC,and 101C.6.Procedure 6.1 The chase of the mold shall be equipped with an immersion well 76 mm(3 in.)in depth.The base of the well shall be located at a point not more than 6.3 mm(Y4 in.)from the surface of the cavity.Insert the thermometer into the well as far as possible.Allow the thermometer to remain in the well until the mercury no longer moves in the column.The thermometer reading at this point shall be considered the mold temperature.In recording the temperature reading,state that the thermometer procedure was used.PROCEDURE USING PYROMETER 7.Apparatus accurate within t1.5C(2.7F)shall be used.the Appendix to Practice D 957.8.Procedure 8.1 Place the thermocouple of the pyrometer at any point on the surface of the cavity and plunger of the mold,making certain good contact is maintained(Note 3).Maintain contact until the needle on the dial scale reaches equilibrium.Record the temperature reading on the dial scale at this point.Take temperature readings at at least four points each on the surfaces of the cavity and plunger of the mold.In recording temperature readings,state that the pyrometer procedure was used.7.1 Pyrometer-A calibrated surface pyrometer(Note 2)NOTE 2-For the procedure for calibration of surface pyrometers,see This practice is under the jurisdiction of ASTM Committee D-20 on Plastics and is the direct responsibility of Subcommittee D 20.09 on Specimen Prepara-*I.-NOTE 3-wax may be to ensure intimate contact the mold surface and the thermocouule of the uvrometer.This i s accom-lion.Current edition approved March 25,1988.Published May 1988.Originally plished by allowing a Small portion of wax,or any suitable material with a low melting point,to melt at the point where the temperature reading is to be taken.The thermocouple is then placed in the puddle of molten material.published as D 958-48 T.Last previous edition D 958-72(1987).Anniral Book of ASTM Standards,Vol 08.01.Annual Book ofASTM Standards,Vols 05.03 and 14.01.1 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.The American Society for Testing and Materials takes no position respecting the validiy of any patent rights asserted in connection with any item mentioned in this standard.Users of this standard are expressly advised that determination of the validity of any such patent rights,and the risk of infringement of such rights,