ASTM D6289-13(2019)
(Test Method)Standard Test Method for Measuring Shrinkage from Mold Dimensions of Molded Thermosetting Plastics
Standard Test Method for Measuring Shrinkage from Mold Dimensions of Molded Thermosetting Plastics
SIGNIFICANCE AND USE
4.1 Compression Molding—In compression molding, the difference between the dimensions of a mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. It is probable that shrinkage will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity or some part of it, or where the molded article is hardened to a maximum while still under pressure, particularly by cooling. In contrast, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all its recesses, or where the molded article is not fully hardened when discharged. The plasticity of the material used affects shrinkage insofar as it affects the retention and compression of the charge.
4.2 Injection Molding—In injection molding, as in compression molding, the differences between the dimensions of the mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. The differences vary with the type and size of molding machine, the thickness of molded sections, the degree and direction of flow or movement of material in the mold, the size of the nozzle, sprue, runner, and gate, the cycle on which the machine is operated, the temperature of the mold, and the length of time that follow-up pressure is maintained. As in the case of compression molding, shrinkages will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity and where the molded article is hardened to a maximum while still under pressure as a result of the use of a runner, sprue, and nozzle of proper size, along with proper dwell. As in compression molding, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all of the recesses...
SCOPE
1.1 This test method is intended to measure shrinkage from mold cavity to molded dimensions of thermosetting plastics when molded by compression, injection, or transfer under specified conditions.
1.2 This test method provides for the measurement of shrinkage of thermosetting plastics from their molds both initially (within 16 to 72 h of molding) and after aging (post–shrinkage at elevated temperatures).
1.3 This method will give comparable data based on standard specimens and can not predict absolute values in actual molded parts with varying flow paths, wall thicknesses, pressure gradiants and process conditions. Differences in mold shrinkage generally is observed between the specimen geometries described in this test method.
1.4 Knowledge of the initial shrinkage of plastics is important for the construction of molds and knowledge of post molding shrinkage is important for determining the suitability of the molding material for manufacturing thermosetting plastic components with accurate dimensions.
1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
Note 1: This test method and ISO 2577-1984 are equivalent when bars of 120 mm length, 15 mm width, and 10 mm thickness are used for compression molding; or flat, square plaques approximately 120 by 120 by 4 mm are used for injection molding.
1.7 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...
General Information
- Status
- Published
- Publication Date
- 30-Apr-2019
- Technical Committee
- D20 - Plastics
- Drafting Committee
- D20.09 - Specimen Preparation
Relations
- Effective Date
- 01-May-2019
- Effective Date
- 01-Feb-2024
- Effective Date
- 01-Nov-2023
- Effective Date
- 01-Jan-2020
- Effective Date
- 01-Aug-2019
- Effective Date
- 01-May-2019
- Effective Date
- 01-May-2019
- Effective Date
- 15-Apr-2019
- Effective Date
- 01-Feb-2019
- Effective Date
- 01-Dec-2018
- Effective Date
- 01-Nov-2018
- Effective Date
- 15-Aug-2017
- Effective Date
- 01-May-2013
- Effective Date
- 15-Nov-2012
- Effective Date
- 01-Apr-2012
Overview
ASTM D6289-13(2019): Standard Test Method for Measuring Shrinkage from Mold Dimensions of Molded Thermosetting Plastics is a key international standard developed by ASTM. The standard outlines precise test methods for determining the dimensional shrinkage that occurs when thermosetting plastics are molded by compression, injection, or transfer molding processes. By measuring both the initial shrinkage (within 16 to 72 hours after molding) and post-molding shrinkage (after aging at elevated temperatures), this standard provides invaluable information for mold designers, material manufacturers, and quality assurance personnel seeking dimensional accuracy in thermoset plastic components.
Thermosetting plastics often exhibit shrinkage due to their inherent material properties and molding processes. Understanding this shrinkage is vital for achieving accurate finished part dimensions in both research and industrial environments.
Key Topics
- Mold Shrinkage Measurement: The procedure compares the dimensions of the mold cavity with those of the molded part under controlled temperature and humidity, highlighting the important variables that impact shrinkage.
- Initial vs. Post-Molding Shrinkage: The standard distinguishes between initial shrinkage (measured after cooling and conditioning) and post-shrinkage (measured after additional heat treatment), reflecting real-world variability due to environmental factors and part aging.
- Applicable Molding Techniques:
- Compression Molding: Shrinkage depends on how well the material is forced into the mold and the extent of hardening under pressure.
- Injection Molding: Influencing factors include machine type, section thickness, flow direction, pressure, and mold temperature.
- Transfer Molding: Affected by pot size, temperature, and molding cycle.
- Influencing Variables: Material plasticity, pressure application, mold design, processing conditions, and section geometry all contribute to shrinkage characteristics.
- Specimen Preparation: Detailed requirements for bars, plaques, and disks molded under precise conditions to minimize variability and enable comparison.
Applications
- Mold Design and Tooling: Accurate measurement of shrinkage is essential for designing molds that produce parts meeting strict dimensional tolerances. Knowledge of both initial and post-molding shrinkage ensures proper compensation in mold construction.
- Quality Control: Manufacturers use this standard to assess batch-to-batch consistency in thermosetting plastic materials, improving product reliability.
- Material Evaluation: The method provides comparable data for evaluating thermosetting plastics, aiding in material selection for specific applications where dimensional stability is critical.
- Process Optimization: By clarifying the relationship between process parameters and resulting shrinkage, the standard supports optimization of molding practices for reduced defects and waste.
- Compliance and Standardization: Testing according to ASTM D6289 ensures alignment with internationally recognized standards, facilitating global trade and regulatory compliance in the plastics industry.
Related Standards
For organizations seeking a comprehensive approach to thermoset plastics shrinkage measurement and molding, the following standards are often referenced alongside ASTM D6289:
- ISO 2577: Plastics - Thermosetting Moulding Materials - Determination of Shrinkage (equivalent for specific specimen types and dimensions)
- ISO 295: Plastics - Compression Moulding Test Specimens of Thermosetting Materials
- ISO 10724: Plastics - Thermosetting Molding Materials - Injection Molding of Multipurpose Test Specimens
- ASTM D618: Practice for Conditioning Plastics for Testing
- ASTM D883: Terminology Relating to Plastics
- ASTM D3419: Practice for In-Line Screw-Injection Molding Test Specimens from Thermosetting Compounds
Keywords: thermosetting plastics, mold shrinkage, ASTM D6289, dimensional stability, compression molding, injection molding, transfer molding, quality control, plastic molding shrinkage, post-molding shrinkage, plastics industry standards.
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Frequently Asked Questions
ASTM D6289-13(2019) is a standard published by ASTM International. Its full title is "Standard Test Method for Measuring Shrinkage from Mold Dimensions of Molded Thermosetting Plastics". This standard covers: SIGNIFICANCE AND USE 4.1 Compression Molding—In compression molding, the difference between the dimensions of a mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. It is probable that shrinkage will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity or some part of it, or where the molded article is hardened to a maximum while still under pressure, particularly by cooling. In contrast, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all its recesses, or where the molded article is not fully hardened when discharged. The plasticity of the material used affects shrinkage insofar as it affects the retention and compression of the charge. 4.2 Injection Molding—In injection molding, as in compression molding, the differences between the dimensions of the mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. The differences vary with the type and size of molding machine, the thickness of molded sections, the degree and direction of flow or movement of material in the mold, the size of the nozzle, sprue, runner, and gate, the cycle on which the machine is operated, the temperature of the mold, and the length of time that follow-up pressure is maintained. As in the case of compression molding, shrinkages will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity and where the molded article is hardened to a maximum while still under pressure as a result of the use of a runner, sprue, and nozzle of proper size, along with proper dwell. As in compression molding, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all of the recesses... SCOPE 1.1 This test method is intended to measure shrinkage from mold cavity to molded dimensions of thermosetting plastics when molded by compression, injection, or transfer under specified conditions. 1.2 This test method provides for the measurement of shrinkage of thermosetting plastics from their molds both initially (within 16 to 72 h of molding) and after aging (post–shrinkage at elevated temperatures). 1.3 This method will give comparable data based on standard specimens and can not predict absolute values in actual molded parts with varying flow paths, wall thicknesses, pressure gradiants and process conditions. Differences in mold shrinkage generally is observed between the specimen geometries described in this test method. 1.4 Knowledge of the initial shrinkage of plastics is important for the construction of molds and knowledge of post molding shrinkage is important for determining the suitability of the molding material for manufacturing thermosetting plastic components with accurate dimensions. 1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Note 1: This test method and ISO 2577-1984 are equivalent when bars of 120 mm length, 15 mm width, and 10 mm thickness are used for compression molding; or flat, square plaques approximately 120 by 120 by 4 mm are used for injection molding. 1.7 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...
SIGNIFICANCE AND USE 4.1 Compression Molding—In compression molding, the difference between the dimensions of a mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. It is probable that shrinkage will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity or some part of it, or where the molded article is hardened to a maximum while still under pressure, particularly by cooling. In contrast, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all its recesses, or where the molded article is not fully hardened when discharged. The plasticity of the material used affects shrinkage insofar as it affects the retention and compression of the charge. 4.2 Injection Molding—In injection molding, as in compression molding, the differences between the dimensions of the mold and of the molded article produced therein from a given material vary according to the design and operation of the mold. The differences vary with the type and size of molding machine, the thickness of molded sections, the degree and direction of flow or movement of material in the mold, the size of the nozzle, sprue, runner, and gate, the cycle on which the machine is operated, the temperature of the mold, and the length of time that follow-up pressure is maintained. As in the case of compression molding, shrinkages will approach a minimum where design and operation are such that a maximum of material is forced solidly into the mold cavity and where the molded article is hardened to a maximum while still under pressure as a result of the use of a runner, sprue, and nozzle of proper size, along with proper dwell. As in compression molding, shrinkages are higher where the charge must flow in the mold cavity but does not receive and transmit enough pressure to be forced firmly into all of the recesses... SCOPE 1.1 This test method is intended to measure shrinkage from mold cavity to molded dimensions of thermosetting plastics when molded by compression, injection, or transfer under specified conditions. 1.2 This test method provides for the measurement of shrinkage of thermosetting plastics from their molds both initially (within 16 to 72 h of molding) and after aging (post–shrinkage at elevated temperatures). 1.3 This method will give comparable data based on standard specimens and can not predict absolute values in actual molded parts with varying flow paths, wall thicknesses, pressure gradiants and process conditions. Differences in mold shrinkage generally is observed between the specimen geometries described in this test method. 1.4 Knowledge of the initial shrinkage of plastics is important for the construction of molds and knowledge of post molding shrinkage is important for determining the suitability of the molding material for manufacturing thermosetting plastic components with accurate dimensions. 1.5 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only. 1.6 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use. Note 1: This test method and ISO 2577-1984 are equivalent when bars of 120 mm length, 15 mm width, and 10 mm thickness are used for compression molding; or flat, square plaques approximately 120 by 120 by 4 mm are used for injection molding. 1.7 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...
ASTM D6289-13(2019) is classified under the following ICS (International Classification for Standards) categories: 83.080.10 - Thermosetting materials. The ICS classification helps identify the subject area and facilitates finding related standards.
ASTM D6289-13(2019) has the following relationships with other standards: It is inter standard links to ASTM D6289-13, ASTM D883-24, ASTM D883-23, ASTM D883-20, ASTM D883-19c, ASTM D3419-12(2019), ASTM D5224-12(2019), ASTM D883-19a, ASTM D883-19, ASTM D883-18a, ASTM D883-18, ASTM D883-17, ASTM E691-13, ASTM D883-12e1, ASTM D3419-12. Understanding these relationships helps ensure you are using the most current and applicable version of the standard.
ASTM D6289-13(2019) is available in PDF format for immediate download after purchase. The document can be added to your cart and obtained through the secure checkout process. Digital delivery ensures instant access to the complete standard document.
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: D6289 − 13 (Reapproved 2019)
Standard Test Method for
Measuring Shrinkage from Mold Dimensions of Molded
Thermosetting Plastics
This standard is issued under the fixed designation D6289; 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 Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
1.1 This test method is intended to measure shrinkage from
Barriers to Trade (TBT) Committee.
mold cavity to molded dimensions of thermosetting plastics
when molded by compression, injection, or transfer under
2. Referenced Documents
specified conditions.
2.1 ASTM Standards:
1.2 This test method provides for the measurement of
D618 Practice for Conditioning Plastics for Testing
shrinkage of thermosetting plastics from their molds both
D796 Practice for Compression Molding Test Specimens of
initially (within 16 to 72 h of molding) and after aging
Phenolic Molding Compounds (Withdrawn 1992)
(post–shrinkage at elevated temperatures).
D883 Terminology Relating to Plastics
1.3 This method will give comparable data based on stan-
D1896 Practice for Transfer Molding Test Specimens of
dard specimens and can not predict absolute values in actual
Thermosetting Compounds
molded parts with varying flow paths, wall thicknesses, pres-
D3419 Practice for In-Line Screw-Injection Molding Test
sure gradiants and process conditions. Differences in mold
Specimens From Thermosetting Compounds
shrinkage generally is observed between the specimen geom-
D5224 PracticeforCompressionMoldingTestSpecimensof
etries described in this test method.
Thermosetting Molding Compounds
E691 Practice for Conducting an Interlaboratory Study to
1.4 Knowledge of the initial shrinkage of plastics is impor-
Determine the Precision of a Test Method
tant for the construction of molds and knowledge of post
2.2 ISO Standards:
molding shrinkage is important for determining the suitability
ISO 291 Plastics—Standard Atmospheres for Conditioning
of the molding material for manufacturing thermosetting plas-
and Testing
tic components with accurate dimensions.
ISO 295 Plastics—Compression Molding Test Specimens of
1.5 The values stated in SI units are to be regarded as
Thermosetting Materials
standard. The values given in parentheses are for information
ISO 10724 Plastics—Thermosetting Molding Materials—
only.
Injection Molding of Multipurpose Test Specimens
1.6 This standard does not purport to address all of the
ISO 2577-1984 Plastics—Thermosetting Moulding
safety concerns, if any, associated with its use. It is the
Materials—Determination of Shrinkage
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
3. Terminology
mine the applicability of regulatory limitations prior to use.
3.1 General—Definitions of terms applying to this test
NOTE1—ThistestmethodandISO2577-1984areequivalentwhenbars method appear in Terminology D883.
of 120 mm length, 15 mm width, and 10 mm thickness are used for
3.2 Definitions:
compression molding; or flat, square plaques approximately 120 by 120
3.2.1 For the purpose of this test method, the following
by 4 mm are used for injection molding.
definitions apply:
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
This test method is under the jurisdiction ofASTM Committee D20 on Plastics the ASTM website.
and is the direct responsibility of Subcommittee D20.09 on Specimen Preparation. The last approved version of this historical standard is referenced on
Current edition approved May 1, 2019. Published May 2019. Originally www.astm.org.
approved in 1998. Last previous edition approved in 2013 as D6289 - 13. DOI: Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D6289-13R19. 4th Floor, New York, NY 10036, http://www.ansi.org.
*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
D6289 − 13 (2019)
3.2.2 molding shrinkage—the difference in dimensions be- 4.5 Utility—Measurement of batch-to-batch consistency in
tween a molding and the mold cavity in which it was molded, initial shrinkage from mold to molded dimensions is useful for
both the mold and the molding being at 23 6 2°C when evaluating the quality of thermosetting plastics.
measured.
5. Sample Preparation
3.2.3 post-shrinkage—shrinkage of a plastic product after
5.1 Some materials require special treatment before they are
molding, during post-treatment, storage or use.
molded. Materials to be tested shall be prepared for molding in
4. Significance and Use
accordance with the relevant material standard or the manu-
4.1 Compression Molding—In compression molding, the
facturer’s recommendations. The preparation given to the
differencebetweenthedimensionsofamoldandofthemolded material prior to molding shall be recorded and reported.
article produced therein from a given material vary according
6. Apparatus
to the design and operation of the mold. It is probable that
shrinkage will approach a minimum where design and opera-
6.1 Mold, Press, etc., suitable for molding the test speci-
tion are such that a maximum of material is forced solidly into mens specified in Section 8. For transfer or compression
the mold cavity or some part of it, or where the molded article
molding, a positive or a semi-positive mold with single or
is hardened to a maximum while still under pressure, particu- multiple cavities shall be used. For injection molding, the type
larly by cooling. In contrast, shrinkages are higher where the
of mold is defined.
charge must flow in the mold cavity but does not receive and 6.1.1 If required, marks are engraved in the mold near
transmit enough pressure to be forced firmly into all its
opposite ends of the specimen to facilitate the accurate
recesses, or where the molded article is not fully hardened measurement of the length of the cavity and the specimens.
when discharged. The plasticity of the material used affects
NOTE2—Ifmultiplecavitiesareusedwithapositivemold,itispossible
shrinkage insofar as it affects the retention and compression of
that resulting variations in test specimen density can be sufficient to
the charge.
produce inconsistent shrinkage.
4.2 Injection Molding—In injection molding, as in compres-
6.2 Equipment, suitable for measuring the lengths of the test
sion molding, the differences between the dimensions of the
specimen and the corresponding cavity of the mold to within
mold and of the molded article produced therein from a given
0.02 mm.
material vary according to the design and operation of the
6.3 Oven, for post-shrinkage only, a forced draft type is
mold. The differences vary with the type and size of molding
recommended.
machine, the thickness of molded sections, the degree and
direction of flow or movement of material in the mold, the size
7. Sampling
of the nozzle, sprue, runner, and gate, the cycle on which the
7.1 Arepresentative sample shall be taken from the molding
machine is operated, the temperature of the mold, and the
material and be kept at room temperature in airtight containers,
length of time that follow-up pressure is maintained.As in the
without any conditioning, until molded into test specimens.
case of compression molding, shrinkages will approach a
minimumwheredesignandoperationaresuchthatamaximum
8. Test Specimen
of material is forced solidly into the mold cavity and where the
8.1 Compression-Molding Materials—For mold shrinkage
molded article is hardened to a maximum while still under
of compression-molding materials, the test specimens shall be
pressure as a result of the use of a runner, sprue, and nozzle of
bars 120 by 15 by 10 mm, bars 12.7 by 12.7 by 127 mm ( ⁄2 by
proper size, along with proper dwell. As in compression
1 1
⁄2 by 5 in.), or disks 3.2 mm ( ⁄8 in.) in thickness and 102 mm
molding, shrinkages are higher where the charge must flow in
(4 in.) in diameter made in a positive mold in such a way as to
the mold cavity but does not receive and transmit enough
minimize lateral movement of the plastic during the molding.
pressure to be forced firmly into all of the recesses of the mold.
8.2 Injection-Molding Materials—For mold shrinkage of
The plasticity of the material used affects shrinkage indirectly,
injection-molding materials, the test specimens shall be bars
inthatthemorereadilyplasticizedmaterialwillrequirealower
1 1
12.7by3.2by127mm( ⁄2by ⁄8by5in.)gatedattheend,bars
molding temperature.
1 1 1
12.7 by 12.7 by 127 mm ( ⁄2 by ⁄2 by 5 in.) disks 3.2 mm ( ⁄8
4.3 Transfer Molding—In transfer molding, as in compres-
in.) in thickness and 102 mm (4 in.) in diameter gated radially
sion or injection molding, the difference between the dimen-
at a single point in the edge, plaques 120 by 120 by 4 mm or
sions of the mold and of the molded article
...
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