ASTM B331-95

Standard Test Method for Compressibility of Metal Powders in Uniaxial Compaction

SCOPE
1.1 This test method covers determination of compressibility of metal powders as measured by the extent to which they can be densified in a specified die under controlled conditions.
1.2 The values stated in inch-pound units are to be regarded as the standard. The SI equivalents are in parentheses and may be approximate.
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.

General Information

• Status: Historical
• Publication Date: 14-Feb-1995
• Technical Committee: B09 - Metal Powders and Metal Powder Products
• Drafting Committee: B09.02 - Base Metal Powders

Relations

• Replaced By: ASTM B331-95(2002) - Standard Test Method for Compressibility of Metal Powders in Uniaxial Compaction
• Effective Date: 15-Feb-1995
• Referred By: ASTM B925-15(2022) - Standard Practices for Production and Preparation of Powder Metallurgy (PM) Test Specimens
• Effective Date: 15-Feb-1995
• Referred By: ASTM B243-23 - Standard Terminology of Powder Metallurgy
• Effective Date: 15-Feb-1995

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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.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: B 331 – 95
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Compressibility of Metal Powders in Uniaxial Compaction
This standard is issued under the fixed designation B 331; 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 5.2 Results may be affected by test conditions such as the
type amount, and method of lubrication, dwell time, and die
1.1 This test method covers determination of compressibil-
material. They may not necessarily agree with results obtained
ity of metal powders as measured by the extent to which they
under production conditions.
can be densified in a specified die under controlled conditions.
1.2 The values stated in inch-pound units are to be regarded
6. Apparatus
as the standard. The SI equivalents are in parentheses and may
6.1 Die and Two Steel Punches—The die should be made of
be approximate.
cemented carbide, or alternatively of tool steel. The set may be
1.3 This standard does not purport to address all of the
designed either for rectangular compacts or round compacts.
safety concerns, if any, associated with its use. It is the
Fig. 1 illustrates typical rectangular tooling and Fig. 2 illus-
responsibility of the user of this standard to establish appro-
trates typical round tooling.
priate safety and health practices and determine the applica-
6.2 Compression Testing Machine or Hydraulic Powder
bility of regulatory limitations prior to use.
Compacting Press, capable of applying an adequate load with
2. Referenced Documents an accuracy of at least 61.0 %.
6.3 Balance, suitable for weighing at least 100 g to the
2.1 ASTM Standards:
nearest 0.01 g.
B 215 Practices for Sampling Finished Lots of Metal Pow-
6.4 Micrometer, or other suitable measuring device for
ders
measuring the dimensions of the compacts to the nearest
B 243 Terminology of Powder Metallurgy
0.0002 in. (0.005 mm).
B 328 Test Method for Density, Oil Content, and Intercon-
nected Porosity of Sintered Powder Metal Structural Parts
7. Sampling
and Oil-Impregnated Bearings
7.1 A quantity of powder capable of producing the required
3. Terminology number of test specimens (see 9.1 and Section 11) shall be
obtained in accordance with Practices B 215.
3.1 Definitions—For definitions of terms used in this test
method refer to Terminology B 243.
8. Preparation of Apparatus
4. Summary of Test Method 8.1 Lubrication is necessary to assist the ejection of the
compacted test specimen from the die. Either die wall lubrica-
4.1 The test method consists of compacting a sample of
tion or powder lubrication may be used.
metal powder in a confining die, ejecting it from the die, and
8.1.1 Unlubricated Powder may be tested in a die with
measuring its green density. The powder is subjected to
lubricated walls. Apply to the die walls a mixture of a lubricant
uniaxial loading in a standardized die of rectangular or of
in a volatile organic liquid. After any excess liquid has drained
round cross section.
away, allow the solution adhering to the walls to evaporate
5. Significance and Use
leaving a thin layer of lubricant.
5.1 The compressibility obtained is a measure of a material
NOTE 1—An example of such a mixture is 100 g of zinc stearate in 1 L
characteristic inherent in the powder. The test method is useful
of methyl alcohol.
as a quality control test in the evaluation and manufacturing
8.1.2 An alternative way of testing powder not containing a
control of metal powder production, and as an acceptance test
lubricant is to use an otherwise unlubricated die after thor-
for shipment of metal powder lots.
oughly mixing into the powder a sufficient amount of a suitable
lubricant.
8.1.3 Lubricated Powder, received already mixed with suf-
This test method is under the jurisdiction of ASTM Committee B-9 on Metal
Powders and Metal Powder Products and is the direct responsibility of Subcom-
ficient lubricant should be tested in an otherwise unlubricated
mittee B09.02 on Base Metal Powders.
die.
Current edition approved Feb. 15, 1995. Published April 1995. Originally
8.2 Compressibility may vary according to the method of
published as B 331 – 58T. Last previous edition B 331 – 85 (1990).
Annual Book of ASTM Standards, Vol 02.05. lubrication, type, and amount of lubricant.
B 331
NOTE 1—The dimensions for the cavity shall be 0.500 6 0.004 in. wide (12.70 6 0.10 mm) by 1.250 6 0.004 in. long (31.75 6 0.10 mm). The mating
parts shall fit freely and should be finished to 4 RMS, or better, to dimensions of 0.0005 in. (0.013 mm) to 0.001 in. (0.025 mm) smaller than the bottom
of the die cavity, in each dimension. The dimensions given in the drawing typify the die cavity and punch within the stated tolerance, at the nominal width
and length dimensions, permitting die wall to punch clearances of 0.00025 to 0.0005 in. (0.006 mm to 0.013 mm) at each of the four sides of the die,
at the bottom of the die. The outer ring may be AISI H-11 steel hardened to 45 to 48 HRC. The punches may be AISI A-7 steel hardened to 60 to 62
HRC. The die insert should be die grade tungsten carbide.
FIG. 1 Example of Tooling to Produce Rectangular Test Piece
8.3 The parties shall agree on the method, amount, and type die cavity to the desired filling height using supporting spacers
of lubricant. between the die and the lower press platen. Pour the powder
sample into the die cavity taking care to ensure that the powder
9. Procedure
is uniformly distributed. Insert the upper punch and then apply
9.1 Powder Sample Mass—The powder sample mass shall
and release a preliminary pressure of approximately 5000 psi
be such as to result in a rectangular compact 0.240 to 0.260 in.
(35 MPa). Remove the spacers supporting the die. If the die is
thick (6.1 to 6.6 mm) or a round compact 0.27 to 0.29 in. (6.9
supported by springs, or in some similar way, it is unnecessary
to 7.4 mm) thick. For a powder whose compressibility is not
to apply the preliminary pressure. Apply the final pressure. In
known, it may be necessary to adjust the powder mass based on
special cases where the results may be affected by the
...