1、Designation: B946 06 (Reapproved 2010)Standard Test Method forSurface Finish of Powder Metallurgy (PM) Products1This standard is issued under the fixed designation B946; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of l
2、ast revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers measuring the surface finish ofpowder metallurgy (PM) products at all stages of manufactur-ing
3、from green compact to fully hardened finished component.1.2 This test method provides the definition and schematicof some common surface finish parameters (Ra,Rt, and Rz ISO)1.3 The values stated in inch-pound units are to be regardedas standard. The values given in parentheses are mathematicalconve
4、rsions to SI units that are provided for information onlyand are not considered standard.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practice
5、s and to determine theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 MPIF Standard:2MPIF Standard 58 Method for Determination of SurfaceFinish of Powder Metallurgy Products3. Significance and Use3.1 The surface finish of a component may be critical forcertain applica
6、tions, affecting properties such as wear resis-tance, fatigue strength, and coefficient of friction.3.2 Surface finish may also be critical for componentassembly or system performance. Dimensional fit and matingsurface interaction may require certain surface finish require-ments to meet performance
7、specifications.4. Interferences4.1 Because many conventional PM materials contain openporosity at the surface, special consideration should be takenwhen measuring surface finish.4.2 The use of a conical point stylus may result in inaccurateor inconsistent surface finish results because the sharper p
8、ointof the stylus may drop into open porosity on the surface of thecomponent.4.3 A chisel point stylus may be used for better accuracyand consistency.4.4 Because the direction of pressing may cause direction-ality in surface finish values, the direction of measurementshould be specified and reported
9、.5. Apparatus5.1 Surface finish measuring instrument.5.2 StylusChisel point, 0.050 in. (1.27 mm) length and0.0004 in. 6 30 % (0.010 mm 6 30 %) tip radius as shown inFig. 1. To limit the possibility of the stylus dropping into opensurface porosity, a chisel point stylus is recommended. If acone stylu
10、s is used, filtering software shall also be used toremove the influence of open surface porosity.6. Sampling, Test Specimens, and Test Units6.1 The test surface shall be clean and free of any oil, dirt,debris, or foreign material.6.2 Sufficient surface area shall be available to permitmultiple trave
11、rses by the measuring instrument.6.3 The test surface shall be flat over a sufficient length (inaccordance with instrument instructions) to allow propermovement of the stylus.7. Procedure7.1 The PM parts manufacturer and purchaser shall agree onthe desired location and direction for surface finish m
12、easure-ment.7.2 Place the surface finish instrument in a position suitablefor measuring the test sample.7.3 Zero and verify the instrument over the surface finishrange expected for the test sample.7.4 Place the test sample under the stylus and then lower thestylus to the measuring position in accord
13、ance with theinstrument instructions.7.5 Measure the surface finish of the test surface. A mini-mum of three traverses at different locations is recommended.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of
14、 Subcom-mittee B09.05 on Structural Parts.Current edition approved Dec. 1, 2010. Published December 2010. Originallypublished 2006. DOI: 10.1520/B0946-06R10.2Metal Powder Industries Federation, 105 College Rd. East, Princeton, NJ08540-6692 U.S.A.1Copyright ASTM International, 100 Barr Harbor Drive,
15、PO Box C700, West Conshohocken, PA 19428-2959, United States.8. Report8.1 Report the surface finish to the nearest whole number inmicroinches (micrometres). Unless otherwise indicated, thesurface finish shall be Ra(average surface roughness) (see Fig.2). Depending on the type of instrument being use
16、d, othersurface finish measures may also be reported.NOTE 1Rtis the maximum peak-to-valley height over the testedlength (absolute value between the highest and lowest peaks) as shown inFig. 3. Rzis the ten-point height or the absolute value of the five highestpeaks and five lowest valleys over the e
17、valuation length as shown in Fig.4. Rzis also known as the ISO ten-point height parameter.8.2 If it has been specified, report the direction of measure-ment with respect to the pressing direction.9. Precision and Bias9.1 PrecisionAn interlaboratory study to determine theprecision of this test method
18、 is currently under development.9.2 BiasNo information can be presented on the bias ofthe procedure in Test Method B946 for measuring surfacefinish because no material having an accepted reference valueis available.10. Keywords10.1 PM; powder metallurgy; powder metallurgy parts;stylus; surface finis
19、h; surface roughnessNote 1The stylus is chisel shaped and has a standard radius on the edge andis 0.050 in. (1.27 mm) wide so that it will not drop into the porosity of the P/Msurface and give a false reading by measuring the cavities.FIG. 1 Chisel Stylus for Surface Finish MeasurementNote 2The arit
20、hmetic average value of filtered roughness profile determinedfrom deviations about the centerline within the evaluation length lm.FIG. 2 RaArithmetic Mean Roughness ValueNote 3The maximum peak-to-valley height of the filtered profile over theevaluation length lm, irrespective of the sampling lengths
21、 le.FIG. 3 RtMaximum Peak-to-Valley HeightB946 06 (2010)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such paten
22、t rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited eithe
23、r for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair he
24、aring you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standar
25、d may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).Note 4The average height difference between the five highest peaks and five lowest valleys contained within a chosen evaluation length.FIG. 4 RzISOTen-Point HeightB946 06 (2010)3
