ASTM D1896/D1896M-10
(Practice)Standard Practice for Transfer Molding Test Specimens of Thermosetting Compounds
Standard Practice for Transfer Molding Test Specimens of Thermosetting Compounds
SIGNIFICANCE AND USE
Transfer molding is particularly suited to thermosetting materials of intermediate plasticity. Fixed molding parameters cannot be specified for each type of material. Molding compounds of the same type come in many different plasticities measured in accordance with Test Methods D3123 and D3795. Consequently, for a given material type, the molding parameters required to produce satisfactory test specimens will often vary dependent on the plasticity of the specific material grade.
The mold shown in this practice provides for a set of five specimens. However, if only certain specimens are desired, the other cavities can be blocked by inserting gate blanks.
Typically, breathing of the mold is not required to release trapped volatile matter as the gas is free to flow from the vent end of the mold. This is a particular advantage for heat-resistant compounds and reduces the tendency for molded specimens to blister at high exposure temperatures.
Flow and knit lines in a molded piece are often sites of mechanical or electrical weakness and can be found in some degree of severity throughout the molded piece. The semisolid molding compound passing through the gate is subject to non-Newtonian flow and, consequently, wrinkles and folds as it travels down the mold cavity. Fibers and other reinforcements in the molding compound align with the flow pattern and, consequently, can orient perpendicular to the axis of the bar at the center and parallel at the surface of the bar. Mold temperature, thermal conductivity and plasticity of the molding compound, degree of preheat, and plunger pressure are parameters that influence the time to fill the mold cavities and the formation of knit lines.
Note 3—If the temperature of the mold is held constant and the plunger pressure varied for a designated thermosetting molding compound, two extreme characteristic conditions can be obtained. If the pressure is low, then the vent end of the cavity will not fully fill, and weld lines will fo...
SCOPE
1.1 This practice covers a general procedure for the transfer molding of mechanical and electrical test specimens of thermosetting molding materials.
Note 1—The utility of this practice has been demonstrated for the molding of thermosetting molding compounds exhibiting intermediate viscosity non-Newtonian flow.
1.2 The values stated in either SI or inch-pound units are to be regarded separately as standard. The values stated in each system are not always exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems can result in nonconformance with this practice.
1.3 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 2—There is no known ISO equivalent to this standard.
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Designation: D1896/D1896M − 10
Standard Practice for
Transfer Molding Test Specimens of Thermosetting
1
Compounds
This standard is issued under the fixed designation D1896/D1896M; 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* 3.1.1 General—Definitions of terms applying to this prac-
tice appear in Terminology D883.
1.1 This practice covers a general procedure for the transfer
molding of mechanical and electrical test specimens of ther- 3.1.2 transfer molding, n—a method of forming articles by
mosetting molding materials.
fusing a plastic material in a chamber and then forcing
essentially the whole mass into a hot mold where it solidifies.
NOTE 1—The utility of this practice has been demonstrated for the
molding of thermosetting molding compounds exhibiting intermediate
3.2 Definitions of Terms Specific to This Standard:
viscosity non-Newtonian flow.
3.2.1 breathing, v—theoperationofopeningamoldorpress
1.2 The values stated in either SI or inch-pound units are to
for a very short period of time at an early stage in the process
be regarded separately as standard. The values stated in each
of cure.
system are not always exact equivalents; therefore, each
3.2.1.1 Discussion—Breathing allows the escape of gas or
system shall be used independently of the other. Combining
vapor from the molding material and reduces the tendency of
values from the two systems can result in nonconformance
thick moldings to blister.
with this practice.
3.2.2 cavity (of a mold), n—the space within a mold to be
1.3 This standard does not purport to address all of the
filled to form the molded product.
safety concerns, if any, associated with its use. It is the
3.2.3 clamp pressure, n—the pressure applied to the mold to
responsibility of the user of this standard to establish appro-
keep it closed, in opposition to the fluid pressure of the
priate safety and health practices and determine the applica-
compressed molding material.
bility of regulatory limitations prior to use.
3.2.4 fill time, n—thetimerequiredtofilleachcavityusedin
NOTE 2—There is no known ISO equivalent to this standard.
the mold. Fill times can be critical to well molded parts (see
2. Referenced Documents
Note 3 under 4.4).
2
2.1 ASTM Standards:
3.2.5 minimum plunger pressure, n—the minimum pressure,
D883 Terminology Relating to Plastics
on the ram, required to just fill each cavity used in the mold at
D957 Practice for Determining Surface Temperature of
a specified temperature and reasonable fill time.
Molds for Plastics
3.2.6 vent, n—a hole, slot, or groove provided in a mold or
D3123 Test Method for Spiral Flow of Low-Pressure Ther-
machine to allow air and gas to escape during molding,
mosetting Molding Compounds
extrusion, or forming.
D3795 Test Method for Thermal Flow, Cure, and Behavior
Properties of PourableThermosetting Materials byTorque
4. Significance and Use
Rheometer
4.1 Transfer molding is particularly suited to thermosetting
3. Terminology
materials of intermediate plasticity. Fixed molding parameters
3.1 Definitions:
cannot be specified for each type of material. Molding com-
pounds of the same type come in many different plasticities
1 measured in accordance with Test Methods D3123 and D3795.
This practice is under the jurisdiction ofASTM Committee D20 on Plastics and
is the direct responsibility of Subcommittee D20.09 on Specimen Preparation. Consequently, for a given material type, the molding param-
Current edition approved Aug. 1, 2010. Published September 2010. Originally
eters required to produce satisfactory test specimens will often
approved in 1961. Last previous edition approved in 2009 as D1896 - 09. DOI:
vary dependent on the plasticity of the specific material grade.
10.1520/D1896_D1896M-10.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
4.2 The mold shown in this practice provides for a set of
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
fivespecimens.However,ifonlycertainspecimensaredesired,
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the other cavities can be blocked by inserting gate blanks.
*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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D1896/D1896M − 10
closed before the plunger operates. A ram speed of 3.6 m/min [140
4.3 Typically, breathing of the mold is not required to
in./min] and a plunger speed of 2.2 m/min [85 in./min] h
...
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:D1896–09 Designation: D1896/D1896M – 10
Standard Practice for
Transfer Molding Test Specimens of Thermosetting
1
Compounds
This standard is issued under the fixed designation D1896/D1896M; 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 a general procedure for the transfer molding of mechanical and electrical test specimens of
thermosetting molding materials.
NOTE 1—The utility of this practice has been demonstrated for the molding of thermosetting molding compounds exhibiting intermediate viscosity
non-Newtonian flow.
1.2 The values stated in either SI or inch-pound units are to be regarded separately as standard.The values stated in each system
are not always exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two
systems maycan result in nonconformance with this practice.
1.3 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 2—There is no known ISO equivalent to this standard.
2. Referenced Documents
2.1 ASTM Standards:
2
D731Test Method for Molding Index of Thermosetting Molding Powder ASTM Standards:
D883 Terminology Relating to Plastics
D957 Practice for Determining Surface Temperature of Molds for Plastics
D3123 Test Method for Spiral Flow of Low-Pressure Thermosetting Molding Compounds
D3795 Test Method for Thermal Flow, Cure, and Behavior Properties of Pourable Thermosetting Materials by Torque
Rheometer
3. Terminology
3.1 Definitions:
3.1.1 General—Definitions of terms applying to this practice appear in Terminology D883.
3.1.2 transfer molding, n—a method of forming articles by fusing a plastic material in a chamber and then forcing essentially
the whole mass into a hot mold where it solidifies.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 breathing, v—the operation of opening a mold or press for a very short period of time at an early stage in the process of
cure.
3.2.1.1 Discussion—Breathing allows the escape of gas or vapor from the molding material and reduces the tendency of thick
moldings to blister.
3.2.2 cavity (of a mold), n—the space within a mold to be filled to form the molded product.
3.2.3 clamp pressure, n—thepressureappliedtothemoldtokeepitclosed,inoppositiontothefluidpressureofthecompressed
molding material.
3.2.4 fill time, n—the time required to fill each cavity used in the mold. Fill times can be critical to well molded parts (see Note
3 under 4.4).
3.2.5 minimum plunger pressure, n—the minimum pressure, on the ram, required to just fill each cavity used in the mold at a
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 Dec.Aug. 1, 2009.2010. Published December 2009.September 2010. Originally approved in 1961. Last previous edition approved in 20042009
as D1896-99(2004).D1896 - 09. DOI: 10.1520/D1896_D1896M-109.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*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
---------------------- Page: 1 ----------------------
D1896/D1896M – 10
specified temperature and reasonable fill time.
3.2.6 vent, n—a hole, slot, or groove provided in a mold or machine to allow air and gas to escape during molding, extrusion,
or forming.
4. Significance and Use
4.1 Transfer molding is particularly suited to thermosetting materials of intermediate plasticity. Fixed molding parameters
cannot be specified for each type of material. Molding compounds of the same type come in many different plasticities measured
in accordance with Test Methods D731, D3123 , and and D3795. Consequently, for a given material type, the molding parameters
required to produce satisfactory test specimens wi
...
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