ASTM D4703-16

Standard Practice for Compression Molding Thermoplastic Materials into Test Specimens, Plaques, or Sheets

SIGNIFICANCE AND USE
4.1 The methods by which sample materials are prepared and molded influence the mechanical properties of the specimen. Unlike injection molding, the objective of compression molding is to produce test specimens or sheets that are both homogeneous and isotropic. Specimens can be molded from powder or pellets such as are received directly from a material manufacturer, particles produced in a recycle recovery operation, or from a milled preform or sheet prepared on a two-roll mill. The powder, pellets, particles, preform, or sheet are melted and molded in a mold designed to produce a finished specimen of a given geometry, size, and thickness, or melted and molded in the form of a smooth plaque or sheet of uniform thickness from which desired specimens are cut, punched, or machined. Working a compound on a two-roll mill prior to molding will disperse and distribute the compound additives in a manner that will affect the physical properties of the compound. The relevant material specification or the material manufacturer shall be consulted to determine the need for milling a sample prior to compression molding. It is important to treat different samples of the same type of material in the same way: if milling was done prior to molding on a material which is to be used as a standard for comparison, all new materials to be tested against this practice shall be prepared and molded in a similar manner.  
4.2 The apparatus and exact conditions required to prepare adequate specimens will usually vary for each plastic material. Apparatus and procedures satisfactory for molding many different plastic materials are given in this practice in Sections 5 and 6. The apparatus and procedures which have been found satisfactory for molding certain specific materials are given in the Appendixes. In any case, the specific apparatus and procedures to be used in producing compression-molded specimens of a given material shall be obtained by reference to the relevant material specification ...
SCOPE
1.1 This practice covers the compression molding of thermoplastic granules and milled stock for the preparation of test specimens.2  
1.2 While conditions for certain materials are given, the primary source of specific conditions shall be the material specification standards for each type of material.  
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 This standard 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 limitations prior to use.
Note 1: The main body of this practice is equivalent to ISO 293-1986. Annex A1 and ISO 293-1986 differ in some details; however, specimens prepared using Annex A1, Procedure A should be equivalent to those prepared using ISO 293-1986, Cooling Method D. Specimens prepared using Annex A1, Procedure C should be equivalent to those prepared using ISO 293-1986, Cooling Method B. However, due to the greater cooling rate tolerances of the ISO standard, specimens prepared in accordance with ISO Cooling Method B may not be equivalent to Annex A1, Procedure C.

General Information

• Status: Published
• Publication Date: 31-Mar-2016
• ICS: 83.080.20 - Thermoplastic materials
• Technical Committee: D20 - Plastics
• Drafting Committee: D20.09 - Specimen Preparation

Relations

• Refers: ASTM D1248-16 - Standard Specification for Polyethylene Plastics Extrusion Materials for Wire and Cable
• Effective Date: 15-Nov-2016

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D4703 − 16
Standard Practice for
Compression Molding Thermoplastic Materials into Test
1
Specimens, Plaques, or Sheets
This standard is issued under the fixed designation D4703; 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.
1. Scope* D4976 Specification for Polyethylene Plastics Molding and
Extrusion Materials
1.1 This practice covers the compression molding of ther-
2.2 ISO Standard:
moplastic granules and milled stock for the preparation of test
2
ISO 293 Plastics—Compression Moulding Test Specimens
specimens.
4
of Thermoplastic Materials
1.2 While conditions for certain materials are given, the
primary source of specific conditions shall be the material
3. Terminology
specification standards for each type of material.
3.1 Definitions of Terms Specific to This Standard:
1.3 Units—The values stated in SI units are to be regarded
3.1.1 average cooling rate (°C/min), n—the cooling rate
as standard. No other units of measurement are included in this
calculated by dividing the difference between the molding and
standard.
demolding temperatures by the time required to cool the mold
to the demolding temperature.
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
3.1.2 cooling rate (°C/h), n—the rate of cooling obtained by
responsibility of the user of this standard to establish appro-
controlling the flow of the cooling fluid in such a way that
priate safety and health practices and determine the applica-
during each 10-min interval, the deviation from this specified
bility of regulatory limitations prior to use.
cooling rate shall not exceed the specified tolerance.
NOTE 1—The main body of this practice is equivalent to ISO 293-1986. 3.1.3 demolding temperature, n—the temperature of the
Annex A1 and ISO 293-1986 differ in some details; however, specimens
mold or the press platens at the end of the cooling time,
prepared using Annex A1, Procedure A should be equivalent to those
measured in the nearest vicinity to the molded material.
prepared using ISO 293-1986, Cooling Method D. Specimens prepared
3.1.3.1 Discussion—For positive molds, holes are normally
using Annex A1, Procedure C should be equivalent to those prepared
drilled in the mold for measuring the temperatures defined in
using ISO 293-1986, Cooling Method B. However, due to the greater
cooling rate tolerances of the ISO standard, specimens prepared in 3.1.3 and 3.1.4.
accordance with ISO Cooling Method B may not be equivalent to Annex
3.1.4 molding temperature, n—the temperature of the mold
A1, Procedure C.
or the press platens during the preheating and molding time,
measured in the nearest vicinity to the molded material.
2. Referenced Documents
3
3.1.5 molding time, n—the time during which full pressure
2.1 ASTM Standards:
is applied while maintaining the molding temperature.
D618 Practice for Conditioning Plastics for Testing
D1248 Specification for Polyethylene Plastics Extrusion
3.1.6 picture frame mold, n—aflatpieceofmetal,usuallyof
Materials for Wire and Cable
brass or steel, that has a center portion removed to provide the
D3350 Specification for Polyethylene Plastics Pipe and Fit-
specified shape and dimensions of the final molding. The
tings Materials
thickness of the metal is dependent on the desired thickness of
thefinishedmolding,takingintoconsiderationtheshrinkageof
the material to be molded. The picture frame mold is some-
1
ThispracticeisunderthejurisdictionofASTMCommitteeD20onPlasticsand
times referred to as a chase.
is the direct responsibility of Subcommittee D20.09 on Specimen Preparation.
Current edition approved April 1, 2016. Published April 2016. Originally
3.1.7 preheating time, n—the time required to heat the
approved in 1991. Last previous edition approved in 2010 as D4703 – 10a. DOI:
material in the mold up to the molding temperature while
10.1520/D4703-16.
maintaining the contact pressure.
2
This practice was created as a coalescence of and replacement for Practices
D1928, D2292, D3010, and D3463.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM ISO/IEC Selected Standards for Testing Plastics, available from ASTM. Also
Standards volume information, refer to the standard’s Document Summary page on available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th
the ASTM website. Fl
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D4703 − 10a D4703 − 16
Standard Practice for
Compression Molding Thermoplastic Materials into Test
1
Specimens, Plaques, or Sheets
This standard is issued under the fixed designation D4703; 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.
1. Scope*
1.1 This practice covers the compression molding of thermoplastic granules and milled stock for the preparation of test
2
specimens.
1.2 While conditions for certain materials are given, the primary source of specific conditions shall be the material specification
standards for each type of material.
1.3 Units—The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information
only. standard. No other units of measurement are included in this standard.
1.4 This standard 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
limitations prior to use.
NOTE 1—The main body of this practice is equivalent to ISO 293-1986. Annex A1 and ISO 293-1986 differ in some details; however, specimens
prepared using Annex A1, Procedure A should be equivalent to those prepared using ISO 293-1986, Cooling Method D. Specimens prepared using Annex
A1, Procedure C should be equivalent to those prepared using ISO 293-1986, Cooling Method B. However, due to the greater cooling rate tolerances of
the ISO standard, specimens prepared in accordance with ISO Cooling Method B may not be equivalent to Annex A1, Procedure C.
2. Referenced Documents
3
2.1 ASTM Standards:
D618 Practice for Conditioning Plastics for Testing
D1248 Specification for Polyethylene Plastics Extrusion Materials for Wire and Cable
D3350 Specification for Polyethylene Plastics Pipe and Fittings Materials
D4976 Specification for Polyethylene Plastics Molding and Extrusion Materials
2.2 ISO Standard:
4
ISO 293-1986 ISO 293 Plastics—Compression Moulding Test Specimens of Thermoplastic Materials
3. Terminology
3.1 Definitions of Terms Specific to This Standard:
3.1.1 average cooling rate (°C/min),n—the cooling rate calculated by dividing the difference between the molding and
demolding temperatures by the time required to cool the mold to the demolding temperature.
3.1.2 cooling rate (°C/h),n—the rate of cooling obtained by controlling the flow of the cooling fluid in such a way that during
each 10-min interval, the deviation from this specified cooling rate shall not exceed the specified tolerance.
3.1.3 demolding temperature, n—the temperature of the mold or the press platens at the end of the cooling time, measured in
the nearest vicinity to the molded material.
1
This practice is under the jurisdiction of ASTM Committee D20 on Plastics and is the direct responsibility of Subcommittee D20.09 on Specimen Preparation.
Current edition approved Nov. 1, 2010April 1, 2016. Published January 2011April 2016. Originally approved in 1991. Last previous edition approved in 2010 as
D4703 – 10.D4703 – 10a. DOI: 10.1520/D4703-10A.10.1520/D4703-16.
2
This practice was created as a coalescence of and replacement for Practices D1928, D2292, D3010, and D3463.
3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
4
ISO/IEC Selected Standards for Testing Plastics, available from ASTM. Also available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor,
New York, NY 10036.
3.1.3.1 Discussion—
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D4703 − 16
For positive molds, holes are normally drilled in the mold for measuring the temperatures defined in 3.1.3 and 3.1.4.
3.1.4 molding temperature, n—the temperature of the mold or the press platens during the preheating and molding time,
measured in the nearest vicinity to the molded material.
3.1.5 molding time, n—the time during which full pressure is applied while maintaining th
...