ASTM D731-95(1999)
(Test Method)Standard Test Method for Molding Index of Thermosetting Molding Powder (Withdrawn 2008)
Standard Test Method for Molding Index of Thermosetting Molding Powder (Withdrawn 2008)
SIGNIFICANCE AND USE
This test method provides a guide for evaluating the moldability of thermosetting molding powders. This test method does not necessarily denote that the molding behavior of different materials will be alike and trials may be necessary to establish the appropriate molding index for each material in question.
The sensitivity of this test diminishes when the molding pressure is decreased below 66 MPa, so pressures lower than this are not ordinarily recommended. This is due to the friction of moving parts and the insensitivity of the pressure switch actuating the timer at these low pressures.
SCOPE
1.1 This test method covers the measurement of the molding index of thermosetting plastics ranging in flow from soft to stiff by selection of appropriate molding pressures within the range from 4.1 to 31.9 MPa.
1.2 The values stated in SI units are to be regarded as standard.
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 1-There is no ISO standard equivalent to this test method.
WITHDRAWN RATIONALE
This test method covered the measurement of the molding index of thermosetting plastics ranging in flow from soft to stiff by selection of appropriate molding pressures within the range from 4.1 to 31.9 MPa.
Formerly under the jurisdiction of Committee D20 on Plastics, this test method was withdrawn in August 2008 in accordance with section 10.5.3.1 of the Regulations Governing ASTM Technical Committees, which requires that standards shall be updated by the end of the eighth year since the last approval date.
General Information
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Standards Content (Sample)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation:D731–95 (Reapproved 1999)
Standard Test Method for
Molding Index of Thermosetting Molding Powder
This standard is issued under the fixed designation D 731; 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 5. Significance and Use
1.1 Thistestmethodcoversthemeasurementofthemolding 5.1 This test method provides a guide for evaluating the
indexofthermosettingplasticsranginginflowfromsofttostiff moldability of thermosetting molding powders. This test
by selection of appropriate molding pressures within the range method does not necessarily denote that the molding behavior
from 4.1 to 31.9 MPa. of different materials will be alike and trials may be necessary
1.2 The values stated in SI units are to be regarded as to establish the appropriate molding index for each material in
standard. question.
1.3 This standard does not purport to address all of the 5.2 The sensitivity of this test diminishes when the molding
safety concerns, if any, associated with its use. It is the pressure is decreased below 66 MPa, so pressures lower than
responsibility of the user of this standard to establish appro- this are not ordinarily recommended. This is due to the friction
priate safety and health practices and determine the applica- of moving parts and the insensitivity of the pressure switch
bility of regulatory limitations prior to use. actuating the timer at these low pressures.
NOTE 1—There is no ISO standard equivalent to this test method.
6. Apparatus
6.1 Mold—A cup mold of the flash type, to produce a
2. Referenced Documents
molded cup as shown in Fig. 1, operated under controlled
2.1 ASTM Standards:
pressure and temperatures and provided with stops so that flash
D 256 Test Methods for Impact Resistance of Plastics and
2 or fin thickness cannot be less than 0.14 mm. The area of the
Electrical Insulating Materials
mold casting creating the molded flash shall be located on top
D 883 Terminology Relating to Plastics
of the cup, flat, perpendicular to the axis of the cup, and in the
D 957 Practice for Determining Mold Surface Temperature
form of an annular ring 3.17 mm (0.125 in.) in width.
of Molds for Plastics
6.2 Thermometer—A 32-mm partial-immersion mercury
E 691 Practice for Conducting an Interlaboratory Study to
thermometer having a diameter just under 4.8 mm and a
Determine the Precision of a Test Method
temperature scale of not more than 20°C/25.4 mm of length.A
pyrometer may be used to determine the temperature of the
3. Terminology
mold surfaces. For properly measuring mold temperatures,
3.1 Definitions: Definitions are in accordance with Termi-
reference should be made to Practice D 957.
nology D 883, unless otherwise specified.
6.3 Heating System—Any conventional means for heating
4. Summary of Test Method the press platens, provided the heat source is constant enough
to maintain the molding temperature within 61°C of the
4.1 A cup mold is mounted in a semi-automatic type press.
specified temperature (see 9.2).
A predetermined quantity of test sample is charged into the
6.4 Pressure System—A semiautomatic press with a fixed
mold, controlled at a temperature dependent upon the test
mold and fully insulated to minimize heat losses shall be used.
material. The minimum force required to mold a cup having a
The use of hand molds is not recommended but may be used to
flashorfinthicknesswithinaspecifiedtoleranceisdetermined.
give an estimate of the molding index. The hydraulic system
This force along with the mold closing time is reported as
shall be provided with a means of pressure regulation so that
molding index.
the load on the mold shall differ by not more than 656.2 N
from the stated value. The capacity of the hydraulic system
ThistestmethodisunderthejurisdictionofASTMCommitteeD-20onPlastics
shall permit a ram travel of approximately 25 mm/s. It is
and is the direct responsibility of Subcommittee D 20.30 on Thermal Properties
recommended that the ram diameter not exceed 100 mm.
(Section D20.30.08).
Current edition approved Feb. 15, 1995. Published April 1995. Originally
published as D 731-50. Last previous edition D 731-90.
2 4
Annual Book of ASTM Standards, Vol 08.01. A detailed drawing of the mold design is available from ASTM Headquarters.
Annual Book of ASTM Standards, Vol 08.03. Order Adjunct: ADJD0731.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D731
and thereby change their molding index or molding behavior.
9. Procedure
9.1 Mount the mold in a press of the semi-automatic type.
Past experience has shown that the rate of flow is sensitive to
the condition of the mold surfaces; preceding materials may
have deposited a film that influences the mold surfaces to the
extent that erroneous results may be obtained unless properly
conditioned prior to testing. A suggested procedure is to
discard the first few cups molded and accept the flow time as
correct when two successive cups molded under test do not
differ by more than1sin time of flow.
9.2 The preferred mold temperature for testing the molding
index for the following materials shall be:
°C
Phenolic 165 6 1
Melamine 155 6 1
Urea 150 6 1
Epoxy 150 6 1
Diallyl phthalate 1506 1
Alkyd 150 6 1
Other temperatures may be used as agreed upon between the
FIG. 1 Cup Mold
manufacturer and the purchaser.
9.3 First determine the proper weight to be used as outlined
7. Test Specimen
in 6.1. Then begin the test with a load sufficient to close the
mold to the fin thickness specified for the type of material
7.1 To determine the weight of the test specimen for
being tested as defined in 6.1. For example, if a 2248 N load is
materials having an Izod impact strength of 27 J/m of notch, or
applied on the mold to make the initial cup and the required fin
less, a cup having a flash or fin thickness of 0.15 to 0.20 mm
thickness is obtained, the next lower load, 1686 N is applied as
shall be molded (see Note 3). The adhering fin shall be
indicated in the following table. If the mold closes to the
removed and the cup weighed to the nearest 0.1 g. This weight
required thickness again, then the 1124 N load is applied. If the
multiplied by 1.1 shall be the weight of the test specimen used.
mold then does not close, the “molding index” is the closing
For materials having an impact above 27 J/m of notch, the
time obtained with the 1686 N load. It is recommended that the
specimen weight is determined in a similar manner, except that
mold loads used be selected from the following table:
cup flash shall not be more than 0.66 mm or less than 0.51 mm
and the amount of material shall be 1.05 times the weight of Total Load Molding Pres-
sure
thiscup.Thetestspecimenshallbeintheformofloosepowder
N MPa
unless preforming is necessary for materials of high bulk.
1112 4.6
Minimum pressure shall be employed in th
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