ASTM D3419-93
(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
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 should become part of the material specification or be agreed upon between the purchaser and the supplier.
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 the standard. The values given in parentheses are for information only.
1.3 This standard does not purport to address all of the safety problems, 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.
1.3 This practice assumes the use of reciprocating screw injection molding machines.
Note 2--This standard is similar in content (but not technically equivalent) to ISO 10724: 1994(E).
General Information
Relations
Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 3419 – 93
Standard Practice for
In-Line Screw-Injection Molding Test Specimens From
Thermosetting Compounds
This standard is issued under the fixed designation D 3419; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope for a very short period of time at an early stage in the process
of cure.
1.1 This practice covers a general procedure for screw-
3.2.2 Discussion—Breathing allows the escape of gas or
injection molding thermosetting materials into test specimens
vapor from the molding material and reduces the tendency of
for Izod or Charpy impact, flexure, tension, compression,
thick moldings to blister.
water-absorption, heat-aging, electrical, modulus in tension or
3.2.3 cavity (of a mold), n—the space within a mold to be
flexure, and heat-deflection temperature tests.
filled to form the molded product.
NOTE 1—The utility of this practice has been demonstrated for the
molding of thermosetting molding compounds exhibiting lower-viscosity
4. Significance and Use
non-Newtonian flow.
4.1 This practice is subject to the definition of injection
1.2 The values stated in SI units are to be regarded as the
molding given in 3.1.2 with the further provision that with
standard. The values given in parentheses are for information
in-line screw injection the plastic compound, heated in a
only.
chamber by conduction and friction, is fluxed by the action of
1.3 This standard does not purport to address all of the
a reciprocating screw and then is forced into a hot mold where
safety problems, if any, associated with its use. It is the
it solidifies. Hereafter, in-line screw-injection molding will be
responsibility of the user of this standard to establish appro-
referred to simply as injection molding.
priate safety and health practices and determine the applica-
4.2 The mold referenced in this practice provides for a set of
bility of regulatory limitations prior to use.
five specimens. However, if only certain specimens are desired,
the other cavities may be blocked by inserting gate blanks.
NOTE 2—There are no ISO standards covering the primary subject of
4.3 Typically, injection-molded test specimens are made
this practice.
with shorter cycles than those used for similar moldings made
2. Referenced Documents
by compression, and the cycle is equal to or faster than that for
2.1 ASTM Standards: transfer molding.
D 883 Terminology Relating to Plastics 4.4 Breathing of the mold is not usually required to release
D 958 Practice for Determining Temperatures of Standard trapped volatile material as the gas is free to flow from the vent
ASTM Molds for Test Specimens of Plastics end of the mold. This is particularly advantageous for heat-
resistant compounds and reduces the tendency for molded
3. Terminology
specimens to blister at high exposure temperatures.
3.1 Definitions:
4.5 Injection molding is intended for low-viscosity com-
3.1.1 General—Definitions of terms applying to this prac- pounds. One set of processing parameters cannot be specified
tice appear in Terminology D 883.
for all types of thermosetting materials, nor for samples of the
3.1.2 injection molding—the process of forming a material same material having different plasticities.
by forcing it, in a fluid state and under pressure, through a
4.6 Materials containing fibrous fillers such as glass roving,
runner system (sprue, runner, and gate(s)) into the cavity of a chopped cloth, or cellulosic fibers can be injection molded, but
closed mold.
their properties will be affected depending upon how much
3.1.3 Discussion—Screw-injection molding and reaction-
fiber breakdown occurs as the compound is worked by the
injection molding are types of injection molding. screw and as it passes through the system of runners and gates.
3.2 Definitions of Terms Specific to This Standard:
The orientation of the fibers in the molded specimen will also
3.2.1 breathing, v—the operation of opening a mold or press affect injection-molded properties.
4.7 Flow and knit lines in a molded piece are often sites of
mechanical or electrical weakness. The fluxed material passing
This practice is under the jurisdiction of ASTM Committee D-20 on Plastics
through the gate wrinkles and folds as it proceeds into the mold
and is the direct responsibility of Subcommittee D20.09 on Specimen Preparation.
Current edition approved Feb. 15, 1993. Published April 1993. Originally
cavity. Knit lines may be found to some degree throughout the
published as D 3419 – 75. Last previous edition D 3419 – 92a.
molded piece; these knit lines affect end-test results. Fibers and
Annual Book of ASTM Standards, Vol 08.01.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 3419
other reinforcements in the molding compound align with the sufficient to maintain a uniform mold temperature within 63°C
flow pattern and, consequently, may be perpendicular to the across the mold surface.
axis of the bar at its center and parallel at its surface. 5.4 Temperature Indicator—Typically, a surface pyrometer
4.8 The Izod impact strength of injection-molded specimens is used to measure the temperature of the molded surface as
containing short fibers will generally be lower than the values specified in Practice D 958.
obtained using compression molding methods. The impact
6. Conditioning
strength may also vary along the axis of the bar due to molding
parameters, flow patterns, and fiber orientation. 6.1 Store the molding compound in moisture barrier con-
4.9 The flexural and tensile strength of injection-molded tainers and keep at standard room temperature at the time of
specimens of molding compounds containing short fibers will molding. Compounds designed for screw-inje
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.