ASTM B962-08
(Test Method)Standard Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes’ Principle
Standard Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes<span class='unicode'>’</span> Principle
SIGNIFICANCE AND USE
The volume of a complex shaped PM part cannot be measured accurately using micrometers or calipers. Since density is mass per unit volume, a precise method for measuring the volume is needed. Archimedes’ principle may be used to calculate the volume of water displaced by an immersed object. For this to be applicable to PM materials that contain surface connected porosity, the surface pores are sealed by oil impregnation or some other means.
The green density of compacted parts or test pieces is normally determined to assist during press set-up, or for quality control purposes. It is also used for determining the compressibility of base powders, mixed powders, and premixes.
The sintered density of sintered PM parts and sintered PM test specimens is used as a quality control measure.
The impregnated density of sintered bearings is normally measured for quality control purposes as bearings are generally supplied and used oil-impregnated.
SCOPE
1.1 This standard describes a method for measuring the density of powder metallurgy products that usually have surface-connected porosity.
1.2 The density of impermeable PM materials, those materials that do not gain mass when immersed in water, may be determined using Test Method B 311.
1.3 The current method is applicable to green compacts, sintered parts, and green and sintered test specimens.
1.4 With the exception of density values, for which the g/cm3 unit is the industry standard, the values stated in SI units are to be regarded as the standard. The values given in parentheses are converted in accordance with IEEE/ASTM SI 10 and are for information only.
1.5 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.
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Designation: B962 − 08
StandardTest Methods for
Density of Compacted or Sintered Powder Metallurgy (PM)
Products Using Archimedes’ Principle
This standard is issued under the fixed designation B962; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope available in the Related Material section of Vol. 02.05 of the
Annual Book of ASTM Standards.
1.1 This standard describes a method for measuring the
density of powder metallurgy products that usually have 3.2 Definitions of Terms Specific to This Standard:
surface-connected porosity. 3.2.1 green density (D )—the mass per unit volume of an
g
unsintered PM part or test specimen.
1.2 The density of impermeable PM materials, those mate-
3.2.2 impregnated density (D)—the mass per unit volume
rials that do not gain mass when immersed in water, may be
i
of a sintered PM part or test specimen, impregnated with oil.
determined using Test Method B311.
3.2.3 sintered density (D )—the mass per unit volume of a
s
1.3 The current method is applicable to green compacts,
sintered, non oil-impregnated PM part or test specimen.
sintered parts, and green and sintered test specimens.
4. Summary of Test Method
1.4 With the exception of density values, for which the
g/cm unitistheindustrystandard,thevaluesstatedinSIunits
4.1 The test specimen is first weighed in air. It is then oil
are to be regarded as the standard. The values given in
impregnated or some other treatment is used to seal the
parentheses are converted in accordance with IEEE/ASTM SI
surface-connectedporosityandthespecimenisreweighed.The
10 and are for information only.
test specimen is then weighed when immersed in water and its
density calculated based on Archimedes’ principle.
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
5. Significance and Use
responsibility of the user of this standard to establish appro-
5.1 The volume of a complex shaped PM part cannot be
priate safety and health practices and determine the applica-
measured accurately using micrometers or calipers. Since
bility of regulatory limitations prior to use.
density is mass per unit volume, a precise method for measur-
ing the volume is needed. Archimedes’principle may be used
2. Referenced Documents
to calculate the volume of water displaced by an immersed
2.1 ASTM Standards:
object. For this to be applicable to PM materials that contain
B243Terminology of Powder Metallurgy
surface connected porosity, the surface pores are sealed by oil
B311Test Method for Density of Powder Metallurgy (PM)
impregnation or some other means.
Materials Containing Less Than Two Percent Porosity
5.2 The green density of compacted parts or test pieces is
2.2 IEEE/ASTM Standard:
normallydeterminedtoassistduringpressset-up,orforquality
SI 10American National Standard for Use of the Interna-
control purposes. It is also used for determining the compress-
tional System of Units (SI): The Modern Metric System
ibility of base powders, mixed powders, and premixes.
3. Terminology
5.3 The sintered density of sintered PM parts and sintered
PM test specimens is used as a quality control measure.
3.1 Definitions of powder metallurgy (PM) terms can be
found in Terminology B243.Additional descriptive material is
5.4 The impregnated density of sintered bearings is nor-
mally measured for quality control purposes as bearings are
generally supplied and used oil-impregnated.
These test methods are under the jurisdiction of ASTM Committee B09 on
Metal Powders and Metal Powder Products and are the direct responsibility of
6. Interferences
Subcommittee B09.04 on Bearings.
6.1 A gain in mass when a test specimen is immersed in
Current edition approved Nov. 1, 2008. Published January 2009. DOI: 10.1520/
B0962-08.
water is an indication that the specimen contains surface-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
connected porosity. Unsealed surface porosity will absorb
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
water and cause the calculated density values to be higher than
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. the true value.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B962 − 08
6.2 Test specimens that contain surface-connected porosity scale. Take care with cut specimens to avoid rough surfaces to
shallbeoilimpregnatedorhavethesurface-connectedporosity whichanairbubblemayadhere.A100-gritsandingorabrasive
sealed by some other means prior to their immersion in water. grinding is recommended to remove all rough surfaces.
7. Apparatus
9. Procedure
7.1 Analytical Balance—Precision single-pan balance that
9.1 The part or test specimen, the analytical balance and
will permit readings within 0.01% of the test specimen mass.
surrounding air shall be at a uniform temperature when
See Table 1.
weighing is performed.
7.2 Water Container—A glass beaker or other suitable
9.2 For the most precise density determinations, duplicate
transparent container should be used to contain the water.
weighings should be made for all mass measurements. Adjust
NOTE 1—A transparent container makes it easier to see air bubbles
the analytical balance to zero prior to each weighing.Average
adhering to the test specimen and specimen support when immersed in
the mass determinations before calculating the density.
water.
NOTE 2—For the most precise density determination, the water con-
9.3 For improved repeatability and reproducibility, verify
tainershouldbeofasizethatthelevelofthewaterdoesnotrisemorethan
the analytical balance periodically with a standard mass that is
2.5 mm (0.10 in.) when the test specimen is lowered into the water.
approximately equal to the part or test specimen mass.
7.3 Water—Distilledordeionizedwatertowhich0.05to0.1
9.4 This standard contains three separate test methods;
volumepercentofawettingagenthasbeenaddedtoreducethe
determination of green density, determination of sintered
effects of surface tension.
density, and determination of impregnated density. Each is
NOTE 3—Degassing the water by evacuation, boiling, or ultrasonic
detailed in the following sections.
agitationhelpstopreventairbubblesfromcollectingonthetestspecimen
and support when immersed in water.
Determination of Green Density
7.4 Test Specimen Support for Weighing in Water—Two
9.5 Thisprocedureisusedtodeterminethegreendensityof
typical arrangements are shown in Fig. 1.The suspension wire
PM parts and test specimens.
may be twisted around the test specimen or the test specimen
9.5.1 Determinethemassofthegreenpartortestspecimen.
may be supported in a wire basket that is attached to the
This is mass A. This and all subsequent weighings shall be to
suspension wire. For either arrangement, a single corrosion-
the precision stated in Table 1.
resistant wire—for example, austenitic stainless steel, copper,
9.5.2 Oil impregnate the green part or test specimen as
ornichrome—shallbeusedforthebasketandsuspensionwire.
follows:
The maximum recommended diameter of suspension wire to
be used for various mass ranges is summarized in Table 2.
Preferred Procedure
NOTE 4—For the most precise density determinations, it is important
9.5.3 Immerse the part or test specimen in oil at room
that the mass and volume of all supporting wires immersed in water be
minimized.
temperature.
9.5.4 Reduce the pressure over the sample to 7 kPa (1 psi)
7.5 Oil for Oil-Impregnation—Oil with a viscosity of
-6 -6 2
or less for 30 minutes, then increase the pressure back to
20×10 to65×10 m /s(20to65cStor100to300SSU)at
atmospheric pressure and keep the sample immersed for at
38°C (100°F) has been found to be suitable.
least 30 minutes.
7.5.1 Inthecaseofoil-impregnatedbearings,makeaneffort
9.5.5 Remove excess oil by wiping gently with an absor-
to match the oil that was originally used to impregnate them.
bent, lint-free material. Take care not to extract oil absorbed
7.6 Vacuum Impregnation Apparatus—Equipment to im-
within the part or test specimen.
pregnate the part or test specimen with oil.
9.5.6 Do not place or store parts on porous surfaces such as
7.7 Thermometer—A thermometer with an accuracy of
paper, cloth, or cardboard as these will absorb oil.
0.5°C (1.0°F) to measure the temperature of the water.
9.5.7 Proceed to 9.5.13.
8. Preparation of Test Specimens Alternative Procedure
9.5.8 Immerse the part or test specimen in oil at a tempera-
8.1 The mass of the test specimen shall be a minimum of
ture of 82 6 5°C (180 6 10°F) for at least 4 hours.
1.0 g. For small parts, several parts may be combined to reach
9.5.9 Cool by immersing in a bath of the same oil held at
the minimum mass.
room temperature and keep in this oil for at least 30 minutes.
8.2 Thoroughly clean all surfaces of the test specimen to
9.5.10 Remove excess oil by wiping gently with an absor-
remove any adhering foreign materials such as dirt or oxide
bent, lint-free material. Take care not to extract oil absorbed
within the part or test specimen.
9.5.11 Donotplaceorstorepartsonporoussurfacessuchas
TABLE 1 Balance Sensitivity
paper, cloth, or cardboard as these will absorb oil.
Mass, Balance Sensitivity,
g g
9.5.12 Proceed to 9.5.13.
less than 10 0.0001
NOTE 5—It may not be necessary to oil impregnate the green part with
10 to less than 100 0.001
oil. There may be enough admixed lubricant present in the surface-
100 to less than 1000 0.01
1000 to less than 10 000 0.1 connected pores to prevent the absorption of water. If the test specimen
gains mass when immersed in water it is an indication that the specimen
B962 − 08
FIG. 1 Methods for Holding the Test Specimen When Weighing in Water
TABLE 2 Maximum Recommended Wire Diameters
9.5.16 The test specimen support and test specimen shall
Mass, Wire Diameter, hangfreelyfromthebalancebeamhook,befreeofairbubbles
g mm (in.)
whenimmersedinthewater,andbeatthesametemperatureas
less than 50 0.12 (0.005)
the water and the balance.
50 to less than 200 0.25 (0.010)
200 to less than 600 0.40 (0.015) 9.5.17 The surface of the water shall be free of dust
600 and greater 0.50 (0.020)
particles.
9.5.18 Weigh the part/test specimen and specimen support
immersed in water. This is mass C.
9.5.19 Remove the part/test specimen from the support.
contains surface-connected porosity and that it needs to be sealed by oil
9.5.20 Weigh the test specimen support immersed in water
impregnation or some other means.
at the same depth as before. This is mass E. The suspension
9.5.13 Determinethemassoftheoil-impregnatedgreenpart
support shall be free of air bubbles and the suspension wire
ortestspecimentotheprecisionstatedinTable1.Thisismass
shall not be immersed below its normal hanging depth, as a
B.
change in depth will change the measured mass.
9.5.14 Support the container of water over the pan of the
balance using a suitable bridge as shown in Fig. 2a. Take care
NOTE 6—Some balances are capable of being tared. This automatically
toensurethatthebridgedoesnotrestrictthefreemovementof
removes the necessity of reweighing the specimen support every time. In
this case, tare the specimen support alone, immersed in water to the same
the balance pan.The container of water may also be supported
depth as with the specimen, before weighing the specimen support and
belowthebalanceforweighinglargerspecimensifthebalance
part/test specimen immersed in water. The mass of the specimen support
has a lower beam hook for this purpose. See Fig. 2b. If this
and specimen immersed in water is mass F, which replaces mass C minus
arrangement is used, it is important to shield the weighing
mass E.
system, including the wire, from the effect of air drafts.
9.5.21 Measure the temperature of the water to the nearest
9.5.15 Suspend the test specimen support along with the
1°C (2°F) and record its density ρ , at that temperature, from
part or test specimen from the beam hook of the balance. The w
Table 3.
water should cover any wire twists and the specimen support
9.5.22 Calculate the green density of a part or test piece
basket by at least 6 mm ( ⁄4 in.) to minimize the effect of
surface tension forces on the weighing. from the following formula:
B962 − 08
FIG. 2 Methods for Weighing in Water
A
TABLE 3 Effect of Temperature on the Density of Air-Free Water
where:
Temperature Density
A = the mass of the green part or test piece in air, g,
°C (°F) g/cm
B = themassoftheoil-impregnatedgreenpartortestpiece,
15 (59.0) 0.9991
g,
16 (60.8) 0.9989
C = the mass of the oil-impregnated part/test specimen and
17 (62.6) 0.9988
specimen support immersed in water, g,
18 (64.4) 0.9986
19 (66.2) 0.9984
E = the mass of the oil-impregnated part/test specimen
20 (68.0) 0.9982
support immersed in water, g,
21 (69.8) 0.9980
F = the mass of the oil-impregnated part/test specimen in
22 (71.6) 0.9978
23 (73.4) 0.9975
water with the mass of the specimen support tared, g,
24 (75.2) 0.9973
and
25 (77.0) 0.9970
ρ = the density of the water, g/cm .
26 (78.8) 0.9968 w
27 (80.6) 0.9965
If the green part did not need to be oil impregnated then use
28 (82.4) 0.9962
the following formula:
29 (84.2) 0.9959
30 (86.0) 0.9956
Aρ
w
A
GreenDensity, D 5 (3)
Metrological Handbook 145, “QualityAssurance for Measurements,” National g
C 2 E
Institute of Standards and Technology, 1990, pp. 9-10.
Determination of Sintered Density
9.6 This procedure is used to determine the sintered density
Aρ
w
GreenDensity, D 5 (1)
g of PM parts and test pieces.
B 2 C 2 E
~ !
9.6.1 Determine the mass of the sintered part or test
or
specimen to the precision stated in Table 1. This is mass A.
Aρ This and all subsequent weighings shall be to the precision
w
GreenDensity, D 5 (2)
g
B 2 F stated in Table 1.
B962 − 08
9.6.2 In order to seal the surface-connected porosity the
F = the mass of the oil-impregnated part/test specimen in
parts/testpiecesareoilimpregnatedortheporesarefilledwith
water with the mass of the specimen support tared, g,
a suitable material. If using oil impregnation, oil impregnate
and
thepartortestspecimenusingoneoftheproceduresdescribed
ρ = the density of the water, g/cm .
w
in sections 9.5.2-9.5.12.
Determination of Impregnated Density
9.6.3 Determine the mass of the oil-impregnated part or test
specimen to the precision stated in Table 1. This is mass
...
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