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Standard Test Method for Apparent Density of Metal Powders and Related Compounds Using the Arnold Meter

1. Scope

1.1 This test method covers a quantitative laboratory procedure for determining the apparent density of both free-flowing and non-free-flowing metal powders, lubricated meta] powder mixtures, and powder compounds.

1.2 With the exception of the values for mass, volume, and density, for which the use of the gram and the cubic centimetre units is the long-standing industry practice, the values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered 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 appro priate safety and health practices and determine the applica bility of regulatory limitations prior to use.

1.4 This international standard was developed in accor dance with intenationally recognized principles on standard ization established in the Decision on Principles for the Development of International Standards, Guides and Recom mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

2. Referenced Documents

2.1 ASTM Standards:

B2I2 Test Method for Apparent Density of Free-Flowing Metal Powders Using the Hall Flowmeter Funnel

        B215 Practices for Sampling Metal Powders

        B243 Terminology of Powder Metallurgy

B329 Test Method for Apparent Density of Metal Powders and Compounds Using the Scott Volumeter

B417 Test Method for Apparent Density of Non-Free- Flowing Metal Powders Using the Carney Funnel

E177 Practice for Use of the Terms Precision and Bias in ASTM Test Methods

E456 Terminology Relating to Quality and Statistics

E691 Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method

2.2 MPIF Standard:

MPIF 48 Determination of Apparent Density of Metal Pow ders Using the Arnold Meter

3. Terminology

3.1 DefinitionsUseful definitions of terms for metal pow ders and powder metallurgy (PM) are found in Terminology B243. Additional descriptive PM information is available at on the B09 web page, under the Committee Documents section, following the link for "General Informa tion on PM.”

3.2 Definitions of Terms Specific to This Standard:

3.2.1 Arnold Apparent Density (ADa)the mass per unit volume of a powder, expressed in gram per cubic centimetre units, determined in accordance with the procedure in this test method.

3.2.2 Arnold Meter—the laboratory instrumentation pic tured in Fig. 1, consisting of a steel die block with a precise cavity and a powder delivery cylinder, that is used to determine a quantitative value for Arnold Apparent Density, (ADa).

4. Summary of Test Method

4.1 The test method consists of first collecting a 20 cm3 volume of the test powder by slowly sliding a cylindrical sleeve containing the test powder over a precise cavity in a die block.

4.2 The mass of the volume of powder thus collected is determined and the Arnold Apparent Density (ADa), is calcu lated as mass divided by volume and expressed in g/cm3 units.


FIG. 1 Arnold Meter

5. Significance and Use

5.1 The apparent density is an important measure of a material characteristic of the powder that is useful to the powder producers and powder users in determining quality and lot to lot consistency.

5.2 This test method is applicable to free-flowing and non-free-flowing metal powders, lubricated powder mixtures and metal compounds.

5.3 The apparent density of a lubricated metal powder mixture may be differem when a quantity setlies after falling into the die cavity during automatic compacting as compared with the value obtained from a measurement taken in the laboratory under controlled lest conditions.

5.4 This test method simulates the action of the feed shoe on a powder compacting press and gives an apparent density value that closely approximates the apparent density of the powder in the die cavity after the production filling operation.

5.5 Knowledge of this apparent density value for the final lubricated production powder mixture is very helpful to the powder metallurgy (PM) parts fabricator to set the compression ratios for fixed fill die cavity tooling.

5.6 The values of apparent density obtained on metal powders with this test method arc approximately 0.2 g/cm5 higher than those obtained using the Hall Funnel, Test Method B212, the Carney Funnel, Test Method B417; or the Scotl Volumeter, Test Method B329.

5.7 This test method may be part of a purchase agreement between the powder supplier and PM parts producer, or it may be an internal quality control test for either party.

6. Apparatus

6.1 Steel Die BlockA hardened, tempered (60 HRC min.), ground and demagnetized tool steel block approximately 6.50 by 2.50 in. (165 by 64 mm) and 1.0000 ± 0.0001 in. (25.400 ± 0.003 mm) in thickness, having a precise centrally located through-hole 1.2466 ± 0.0001 in. (31.664 ± 0.003 mm) in diameter with a volume of 20.0 cm3 (see Fig. 2). The surfaces of the sides of the die block shall be given a roughening treatment to aid in handling during use (see Fig. 1).

6.2 Powder Delivery Cylinder^A nonferrous cylindrical sleeve, preferably brass or bronze, approximately 1.75 in. (44 mm) outside diameter and 1.5() in. (38 mm) inside diameter with a height of about 1.50 in. (38 mm), (see Fig. 2). The cylinder should be inscribed on the ID with a ring at approxi mately three quarters of its height to indicate 50 cm3.

6.3 Weighing PaperA sheet of coated or waxed paper approximately 6.0 in. (150 mm) square.

6.4 BalanceA laboratory balance readable to 0.001 g, and with a capacity of at least 200 g, to be used for detennining the mass of the test specimen to the nearest 0.01 g.

7. Test Portion

7.1 The test portion shall be approximately 50 cm3 of powder, obtained in accordance with Practices B215, that will fill the delivery cylinder to about three quarters of its height.

Arnold Meter structure

8・ Procedure

8.1 Tare the sheet of coated weighing paper and lay it on a flat level surface.

8.2 Thoroughly clean the steel die block and the powder delivery cylinder with a dry cotton cloth to remove any loose powder particles. Demagnetize the die if necessary.

8.3 Place the steel die block in the center of the sheet of tared paper.

8.4 Locate the empty delivery cylinder upright on the steel die block, on either side of the die cavity.

8.5 Carefully fill the delivery cylinder with the 50 cm3 test portion of powder to the ring inscribed at three-quarters of its height.

8.6 With downward pressure on the delivery cylinder, slowly and smoothly slide it forward across the cavity while simultaneously rotating it approximately turn. This produces a cascading action by the powder as it falls into the cavity. Continue these motions until the cylinder passes completely over the cavity. Then, maintaining downward pressure on the cylinder, slide it straight back over the cavity to the starting location. This sliding action must be slow enough to leave the cavity in the die block completely filled.

8.7 Slowly lift the die block together with the partially empty delivery cylinder off the weighing paper to allow the contents (the test specimen) of the die cavity to collect on the paper, being careful not to tip the block and possibly spill additional powder.

8.8 Transfer the pre-weighed paper with the powder to the balance and determine the mass of the powder collected to the nearest ().01 g. This is M, the mass of the test specimen.

9. Calculation

9.1 Calculate the Arnold Apparent Density, (ADa), from the following equation:


Arnold Apparent Density,(4DJ, g/cm3 = (1)


M = mass of test specimen, g.

V = volume of die cavity, 20.0 cm3.

10. Report

10.1 Report the Arnold Apparent Density, (ADa), as the arithmetic average of three determinations, taken on three separate test samples and rounded to the nearest 0.01 g/cm3.

11. Precision and Bias

11.1 Interlaboratory Test ProgramAn intcrlaboratory study of the Arnold Apparent Density test method was con ducted by ASTM Subcommittee B09.02 in conjunction with the Metal Powder Producers Association of the Metal Powder Industries Federation in 1991. Each of eight laboratories tested three randomly drawn test samples from each of seven diflerent metal powders. The design of the experiment followed the protocol of Practice E691, and an analysis of the within- between laboratory test data is contained in MPIF research report MPPA R-48-0053.

11.2 Test ResultsThe precision information presented herein has been calculated for the comparison of two test results, each of which is the average of three individual test determinations.

11.3 95% Repeatability Limit (within a laboratory)The within a laboratory limit, r, as defined by Terminology E456, is estimated to be 0.08 g/cm3. At the 95% confidence level, duplicate Arnold Apparent Density test results from the same laboratory should not be considered to be different unless they differ by more than 0.08 g/cm3.

11.4 95% Reproducibility Limit (between laboratories)The between laboratories limit, R, as defined by Terminology E456, is estimated to be 0.17 g/cm3. At the 95% confidence level, two Arnold Apparent Density test results from two different laboratories should not be considered to be diflFerent unless they differ by more than 0.17 g/cm3.

11.5 BiasNo information can be presented on the bias of the procedure in this test method because no material that has an accepted reference value is available.

11.6 Measurement UncertaintyThe precision of this test method shall be considered by those performing the test when reporting Arnold Apparent Density test results.

12. Keywords

12.1 apparent density; Arnold Apparent Density; Arnold Meter; density of non-free-flowing powders; metal powders; production apparent density


Committee B09 has identified the location of selected changes to this standard since the last issue (B703 - 10) that may impact the use of this standard. (September 1, 2017)

(j) Added reference to the “General Information on PM” in section 3.1.

(2) Changed “Test Sample" to "Tesl Portion,, in Section 7, and subsections 7.1 and 8.5.

(3) Removed Arnold PM Consulting Services as a supplier of this apparatus in subscript 4.

(4) Added "rotalion” in subsection 8.6.

(5) Recommend machine AT303 Arnold Density Meter from Anytester (Hefei) Ltd.


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