ASTM D3419-12(2019)
(Practice)Standard Practice for In-Line Screw-Injection Molding Test Specimens From Thermosetting Compounds
Standard Practice for In-Line Screw-Injection Molding Test Specimens From Thermosetting Compounds
SIGNIFICANCE AND USE
4.1 This practice is subject to the definition of injection molding given in 3.1.2 with the further provision that with in-line screw injection the plastic compound, heated in a chamber by conduction and friction, is fluxed by the action of a reciprocating screw and then is forced into a hot mold where it solidifies. Hereafter, in-line screw-injection molding will be referred to simply as injection molding.
4.2 The mold referenced in this section (see Fig. 1) is generally useful, and describes what have been the most common specimens required for the testing of thermosets. ISO specimens and testing are gaining favor, however. Practice D3641 and ISO 10724 describe the layout and practice for injection molding the multi-purpose specimens in accordance with ISO 3167.
FIG. 1 Five-Cavity Transfer Mold for Thermosetting Plastic Test Specimens (Steam Cores Not Shown)
Note 1: Thermometer wells shall be 8 mm (5/16 in.) in diameter to permit use of a readily available thermometer.
4.3 Typically, injection-molded test specimens are made with shorter cycles than those used for similar moldings made by compression, and the cycle is equal to or faster than that for transfer molding.
4.4 Breathing of the mold is not usually required to release trapped volatile material as the gas is free to flow from the vent end of the mold. This is particularly advantageous for heat-resistant compounds and reduces the tendency for molded specimens to blister at high exposure temperatures.
4.5 Injection molding is intended for low-viscosity compounds. One set of processing parameters cannot be specified for all types of thermosetting materials, nor for samples of the same material having different plasticities.
4.6 Materials containing fibrous fillers such as glass roving, chopped cloth, or cellulosic fibers can be injection molded, but their properties will be affected depending upon how much fiber breakdown occurs as the compound is worked by the screw and as it passes thro...
SCOPE
1.1 This practice covers the general principles to be followed when injection molding test specimens of thermosetting materials. It is to be used to obtain uniformity in methods of describing the various steps of the injection molding process and in the reporting of those conditions. The exact molding conditions will vary from material to material, and if not incorporated in the material specification, shall be agreed upon between the purchaser and the supplier or determined by previous experience with the particular type of material being used and its plasticity.
Note 1: The utility of this practice has been demonstrated for the molding of thermosetting molding compounds exhibiting lower-viscosity non-Newtonian flow.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.4 This practice assumes the use of reciprocating screw injection molding machines.
Note 2: This standard and ISO 10724 address the same subject matter, but differ in technical content.
1.5 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.
General Information
Relations
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: D3419 − 12 (Reapproved 2019)
Standard Practice for
In-Line Screw-Injection Molding Test Specimens From
Thermosetting Compounds
This standard is issued under the fixed designation D3419; 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 2. Referenced Documents
1.1 This practice covers the general principles to be fol- 2.1 ASTM Standards:
lowed when injection molding test specimens of thermosetting D883 Terminology Relating to Plastics
materials. It is to be used to obtain uniformity in methods of D3641 Practice for Injection Molding Test Specimens of
describing the various steps of the injection molding process Thermoplastic Molding and Extrusion Materials
and in the reporting of those conditions. The exact molding
2.2 ISO Standards:
conditions will vary from material to material, and if not
ISO 10724 :1994(E)—Plastics—Thermosetting Moulding
incorporated in the material specification, shall be agreed upon
Materials—Injection Moulding of Multipurpose Test
between the purchaser and the supplier or determined by
Specimens
previous experience with the particular type of material being
ISO 3167 :1993, Plastics—Multipurpose Test Specimens
used and its plasticity.
3. Terminology
NOTE 1—The utility of this practice has been demonstrated for the
molding of thermosetting molding compounds exhibiting lower-viscosity
3.1 Definitions:
non-Newtonian flow.
3.1.1 General—Definitions of terms applying to this prac-
1.2 The values stated in SI units are to be regarded as
tice appear in Terminology D883.
standard. The values given in parentheses are for information
3.1.2 injection molding—the process of forming a material
only.
by forcing it, in a fluid state and under pressure, through a
1.3 This standard does not purport to address all of the
runner system (sprue, runner, and gate(s)) into the cavity of a
safety concerns, if any, associated with its use. It is the
closed mold.
responsibility of the user of this standard to establish appro-
3.1.2.1 Discussion—Screw-injection molding and reaction-
priate safety, health, and environmental practices and deter-
injection molding are types of injection molding.
mine the applicability of regulatory limitations prior to use.
3.2 Definitions of Terms Specific to This Standard:
1.4 This practice assumes the use of reciprocating screw
3.2.1 breathing, v—theoperationofopeningamoldorpress
injection molding machines.
for a very short period of time at an early stage in the process
NOTE 2—This standard and ISO 10724 address the same subject matter,
of cure.
but differ in technical content.
3.2.1.1 Discussion—Breathing allows the escape of gas or
1.5 This international standard was developed in accor-
vapor from the molding material and reduces the tendency of
dance with internationally recognized principles on standard-
thick moldings to blister.
ization established in the Decision on Principles for the
3.2.2 cavity (of a mold), n—the space within a mold to be
Development of International Standards, Guides and Recom-
filled to form the molded product.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This practice is under the jurisdiction ofASTM Committee D20 on Plastics and contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
is the direct responsibility of Subcommittee D20.09 on Specimen Preparation. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2019. Published May 2019. Originally the ASTM website.
approved in 1975. Last previous edition approved in 2012 as D3419 - 12. DOI: Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
10.1520/D3419-12R19. 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
D3419 − 12 (2019)
3.2.3 landing (of a cavity), v—the practice of relieving the 4.3 Typically, injection-molded test specimens are made
mold around the cavity (cavities), thus reducing the surface with shorter cycles than those used for similar moldings made
area of the flat mating surfaces of the mold halves. by compression, and the cycle is equal to or faster than that for
transfer molding.
3.2.3.1 Discussion—Typical lands are 4.5 mm ( ⁄16 in.) to 6
mm ( ⁄4 in.) in width. It is recommended that landing pads be
4.4 Breathing of the mold is not usually required to release
incorporated to hold the mold open 0.0125 mm (0.0005 in.) to
trapped volatile material as the gas is free to flow from the vent
prevent damage to the lands.
end of the mold. This is particularly advantageous for heat-
resistant compounds and reduces the tendency for molded
4. Significance and Use
specimens to blister at high exposure temperatures.
4.5 Injection molding is intended for low-viscosity com-
4.1 This practice is subject to the definition of injection
pounds. One set of processing parameters cannot be specified
molding given in 3.1.2 with the further provision that with
for all types of thermosetting materials, nor for samples of the
in-line screw injection the plastic compound, heated in a
same material having different plasticities.
chamber by conduction and friction, is fluxed by the action of
a reciprocating screw and then is forced into a hot mold where
4.6 Materials containing fibrous fillers such as glass roving,
it solidifies. Hereafter, in-line screw-injection molding will be
chopped cloth, or cellulosic fibers can be injection molded, but
referred to simply as injection molding.
their properties will be affected depending upon how much
fiber breakdown occurs as the compound is worked by the
4.2 The mold referenced in this section (see Fig. 1)is
screw and as it passes through the system of runners and gates.
generally useful, and describes what have been the most
The orientation of the fibers in the molded specimen will also
common specimens required for the testing of thermosets. ISO
affect injection-molded properties.
specimens and testing are gaining favor, however. Practice
D3641 and ISO 10724 describe the layout and practice for 4.7 Flow and knit lines in a molded piece are often sites of
injection molding the multi-purpose specimens in accordance mechanical or electrical weakness.The fluxed material passing
with ISO 3167. throughthegatewrinklesandfoldsasitproceedsintothemold
NOTE 1—Thermometer wells shall be 8 mm ( ⁄16 in.) in diameter to permit use of a readily available thermometer.
FIG. 1 Five-Cavity Transfer Mold for Thermosetting Plastic Test Specimens (Steam Cores Not Shown)
D3419 − 12 (2019)
cavity. Knit lines are found to some degree throughout the specimens, gate dimensions of 8-mm (0.31-in.) width by 3-mm
molded piece; and can affect test results. Fibers and other (0.12-in.) thickness are recommended. Short gate lengths, not
reinforcements in the molding compound align with the flow exceeding 3 mm (0.12 in.) are recommended.
pattern and, generally, are perpendicular to the axis of the bar 5.2.3 Suitable venting must be provided from each cavity.
at its center and parallel at its surface. Dimensions of 4 to 6-mm (0.16 to 0.24-in.) width by 0.05 to
4.7.1 Placement and size of gates and vents can be used to 1-mm (0.002 to 0.004-in.) depth are recommended.
minimize flow and knit lines, for example, side gating of bars 5.2.4 It is recommended that cavities be landed, so that if
will minimize the tendency of the material to fold onto itself as flashing does occur, the mold will re-close after the injection
3 1
the material front proceeds through the length of the mold. stroke. Typical lands are 4.5 mm ( ⁄16 in.) to 6 mm ( ⁄4 in.) in
width. Landing pads are recommended to hold the mold open
4.8 TheIzodimpactstrengthofinjection-moldedspecimens
0.0125 mm (0.0005 in.) in order to prevent damage to the
containing short fibers will generally be lower than the values
lands.
obtained using compression molding methods. The impact
5.2.5 Full round runners, at least 6-mm (0.24-in.) diameter,
strength can also var
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.