The dimensional change obtained under specified conditions of pressing and sintering is a material characteristic inherent in the powder. It is useful to the production, testing, and use of metal powders.
The absolute dimensional change may be used to classify powders or differentiate one type or grade from another, to evaluate additions to the powder mix or measure process changes, and to guide in the design of tooling.
The comparative dimensional change is mainly used as a quality control test to measure variations between lots of metal powders of the same material composition.
Factors known to affect size change are the test specimen process conditions of green density, sinter time, sinter temperature, sinter atmosphere, level of additions to the base metal powder, lubricant type, powder grade, powder type, and powder lot.
1.1 This test method covers a procedure for determining the change in dimensions that occurs as a result of sintering a metal powder specimen. The size change referred to is the difference between the die size and the size of the sintered specimen after it has cooled to room temperature, expressed as a percentage. This size change is a basic characteristic of the metal powder.
1.2 The general procedure of measuring a test specimen and die, the calculating he dimensional changes, as described in this test method, also may be used to determine green expansion, heat treat changes, or other dimensional changes of test specimens that result from processing steps.
1.3 The values stated in inch-pound units are to be regarded as the standard. The SI equivalents are in parentheses and may be approximate.
1.4 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.
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