1、Designation: B946 11Standard 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 last revision. A nu
2、mber 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 from green compact
3、 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 units
4、 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 determine
5、 theapplicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 MPIF Standard:2MPIF Standard 58 Method for Determination of SurfaceFinish of Powder Metallurgy Produc
6、ts3. Significance and Use3.1 The surface finish of a component may be critical forcertain applications, 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 an
7、d matingsurface interaction may require certain surface finish require-ments to meet performance 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
8、point stylus may result in inaccurateor inconsistent surface finish results because the sharper pointof 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 direc
9、tion-ality in surface finish values, the direction of measurementshould be specified and reported.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 th
10、e stylus dropping into opensurface porosity, a chisel point stylus is recommended. If acone stylus 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,d
11、ebris, or foreign material.6.2 Sufficient surface area shall be available to permitmultiple traverses 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
12、 manufacturer and purchaser shall agree onthe desired location and direction for surface finish measure-ment.1This test method is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibility of Subcom-mittee B09.05 on Structural Parts.Curren
13、t edition approved May 1, 2011. Published May 2011. Originallypublished 2006. Last previous edition published 2010 as B94606(2010). DOI:10.1520/B0946-11.2Metal Powder Industries Federation, 105 College Rd. East, Princeton, NJ08540-6692 U.S.A.1Copyright ASTM International, 100 Barr Harbor Drive, PO B
14、ox C700, West Conshohocken, PA 19428-2959, United States.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
15、thestylus to the measuring position in accordance with theinstrument instructions.7.5 Measure the surface finish of the test surface. A mini-mum of three traverses at different locations is recommended.8. Report8.1 Report the surface finish to the nearest whole number inmicroinches (micrometres). Un
16、less 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 the maximum peak-to-valley height over the testedlength (absolute value between the highest and
17、 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 ten-point height parameter.8.2 If it has been specified, report the direction of measure-ment wi
18、th respect to the pressing direction.9. Precision and BiasThe Precision for this standard was developed by the MetalPowder Industries Federation (MPIF) and is used herein withtheir permission.9.1 PrecisionThe precision of this test has been deter-mined from an interlaboratory study performed in 2007
19、 inwhich 11 Metal Powder Industries Federation laboratoriesparticipated.9.1.1 The repeatability (r) and reproducibility (R) measure-ments listed in Table 1 were determined according to PracticeE691.9.1.2 FLC2-4808 sinter-hardened transverse rupture testspecimens with a sintered density of 6.94 g/cm3
20、 and anapparent hardness of 45 HRC were used in the study. Eachlaboratory received a single TRS sample from this batch.9.1.3 On the basis of test error alone, the difference inabsolute value of two test results obtained in the samelaboratory will be expected to exceed (r) only 5% of the time.If such
21、 a difference is found to be larger than (r), there is reasonto question one or both results. Similarly, the difference in twotest results obtained in different laboratories will be expected toexceed (R) only 5% of the time. If the difference is found to belarger than (R), there is reason to questio
22、n one or bothmeasurements.9.1.4 The analysis is based on three measurements persurface using a length of travel that varied from 0.098 inch(2.49 mm) to 0.5 inch (12.7 mm). Some laboratories used therecommended chisel stylus, others used the conventional fullradius stylus point and one laboratory pro
23、vided data using bothtypes of stylus.TABLE 1 Precision of Surface Finish Measurements on Sinter-Hardened FLC2-4808 TRS SpecimensSurface Tested Type of Stylus Surface Finish r Rmicroinch (micrometres)Punch Face Chisel 66 (1.65) 8 (0.20) 19 (0.48)Die Face Chisel 26 (0.65) 29 (0.73) 40 (1.00)Punch Face
24、 Spherical 70 (1.75) 38 (0.95) 56 (1.40)Die Face Spherical 36 (0.90) 14 (0.35) 52 (1.30)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.Note 1The stylus is chisel sh
25、aped 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 arithmetic average value of filtered roughness profil
26、e 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 le.FIG. 3 RtMaximum Peak-to-Valley HeightB946 11
27、210. Keywords10.1 PM; powder metallurgy; powder metallurgy parts;stylus; surface finish; surface roughnessASTM 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 tha
28、t determination of the validity of any such patent 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 reappro
29、ved or withdrawn. Your comments are invited either 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 fe
30、el that your comments have not received a fair hearing 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 rep
31、rints (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). 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 113
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