1、Designation: D957 12Standard Practice forDetermining Surface Temperature of Molds for Plastics1This standard is issued under the fixed designation D957; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A n
2、umber 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 is intended for determining the tempera-ture at a specified point or points on the surface of the cavityand base of a mol
3、d for plastics. By determining the temperatureat as many points as deemed necessary, the overall temperaturecondition of the surface can be determined.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does no
4、t 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.NOTE 1There is no known ISO equivalent t
5、o this standard.2. Summary of Practice2.1 With the use of a calibrated surface or radiation (infra-red) non-contact pyrometer, the overall temperature conditionof a mold for plastics can be determined by taking readings ata specified point or many points on the mold surface.3. Significance and Use3.
6、1 The properties of molded parts and the ease of produc-ing satisfactory specimens are influenced by the temperature ofthe mold. It is desirable to know the actual mold temperature,which can differ from the mold temperature control medium.3.2 The user needs to be aware of temperature differencesacro
7、ss the mold/thermocouple interface and at leads, and takeappropriate precautions to minimize such differences.4. Apparatus4.1 Surface PyrometerA calibrated temperature devicedesigned to measure surface temperatures that is traceable tothe international system of units (SI) through a nationalmetrolog
8、y institute (NMI)2accurate to within 61.5C shall beused.4.2 Non-Contact PyrometerA Radiation (infrared) Ther-mometer that is traceable to the international system of units(SI) through a national metrology institute (NMI)2accurate towithin 61.5C shall be used. Radiation Thermometers withselectable em
9、issivity shall be set to the estimated emissivity ofthe surface to be measured. An emissivity correction shall bemade when using Radiation Thermometers with a presetemissivity.5. Procedure5.1 The size, shape, and contours of a mold determine thelocation and number of points at which temperature read
10、ingsare observed. Take temperature readings at as many points asdeemed necessary to determine the temperature condition ofthe mold surface. At a minimum, it is suggested that tempera-tures be measured at the mold center, near the edge, and at leasttwo different but intermediate points between the ce
11、nter andedge.5.2 Place the thermocouple of the pyrometer at any speci-fied point on the surface of the cavity and base of the mold,making certain that good contact is maintained between thetwo (see Note 2). Maintain contact until the scale reachesequilibrium. Record the temperature reading on the sc
12、ale at thispoint.NOTE 2Wax, or any suitable material with a low melting temperature,can be used to ensure intimate contact between the mold surface and thethermocouple of the pyrometer. This is accomplished by allowing a smallportion of the material to melt at the point where the temperature reading
13、is to be taken. The thermocouple is then placed in the puddle of moltenmaterial.6. Keywords6.1 base; cavity; mold temperature; pyrometer1This practice is under the jurisdiction of ASTM Committee D20 on Plastics andis the direct responsibility of Subcommittee D20.09 on Specimen Preparation.Current ed
14、ition approved Nov. 15, 2012. Published December 2012. Originallyapproved in 1948. Last previous edition approved in 2006 as D957 - 06. DOI:10.1520/D0957-12.2NMI includes such organizations as the National Institute of Standards andTechnology.*A Summary of Changes section appears at the end of this
15、standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1SUMMARY OF CHANGESCommittee D20 has identified the location of selected changes to this standard since the last issue (D957 - 06that may impact the use of this standard. (Novembe
16、r 15, 2012)(1) Revision of ISO equivalency statement.(2) Inclusion of use of non-contact pyrometers.(3) Removal of permissive language.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this stand
17、ard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andi
18、f not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, wh
19、ich you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,
20、United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).D957 122
