1、Designation: B 946 06Standard Test Method forSurface Finish of Powder Metallurgy (P/M) Products1This standard is issued under the fixed designation B 946; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers measuring the surface finish ofpowder metallurgy (P/M) products at all stages of manufactur-ing from green co
3、mpact 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 mathematicalconversions to SI
4、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 practices and to dete
5、rmine 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 applications, affect
6、ing 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 specification
7、s.4. Interferences4.1 Because many conventional P/M 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 pointof the s
8、tylus may drop into open porosity on the surface of thecomponent.4.3 A chisel point stylus should 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.5. Appar
9、atus5.1 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 stylus is used
10、, 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 traverses by t
11、he 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 P/M parts manufacturer and purchaser shall agreeon the desired location and direction for surface finish mea-surem
12、ent.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 accordance wit
13、h 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 Subcom-
14、mittee B09.05 on Structural Parts.Current edition approved June 1, 2006. Published June 2006.2Metal Powder Industries Federation, 105 College Rd. East, Princeton, NJ08540-6692 U.S.A.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.8.
15、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 used, othersurface finish measures may also be reported.NOTE 1Rtis
16、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 evaluation length as shown in Fig.4. Rzis also known as the ISO t
17、en-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 is currently under development.9.2 BiasNo information can be pr
18、esented on the bias ofthe procedure in Test Method B 946 for measuring surfacefinish because no material having an accepted reference valueis available.10. Keywords10.1 P/M; powder metallurgy; powder metallurgy parts;stylus; surface finish; surface roughnessNOTE 1The stylus is chisel shaped and has
19、a standard radius on theedge and is 0.050 in. (1.27 mm) wide so that it will not drop into theporosity of the P/M surface and give a false reading by measuring thecavities.FIG. 1 Chisel Stylus for Surface Finish MeasurementNOTE 1The arithmetic average value of filtered roughness profiledetermined fr
20、om deviations about the centerline within the evaluationlength lm.FIG. 2 RaArithmetic Mean Roughness ValueNOTE 1The maximum peak-to-valley height of the filtered profileover the evaluation length lm, irrespective of the sampling lengths le.FIG. 3 RtMaximum Peak-to-Valley HeightB946062ASTM Internatio
21、nal 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 patent rights, and the riskof infringement of such rights, are entirely their
22、 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 either for revision of this standard or for additional standardsand should be
23、 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 hearing you shouldmake your views known to the ASTM Committee on Standards
24、, 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 standard 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).NOTE 1The average height difference between the five highest peaks and five lowest valleys contained within a chosen evaluation length.FIG. 4 RzISOTen-Point HeightB946063
