1、Designation: B 438/B 438M 05Standard Specification forBronze Powder Metallurgy (P/M) Bearings (Oil-Impregnated)1This standard is issued under the fixed designation B 438/B 438M; the number immediately following the designation indicates the yearof original adoption or, in the case of revision, the y
2、ear of last revision. A number in parentheses indicates the year of last reapproval.A superscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1. Scope1.1 This specification covers sin
3、tered bronze, oil-impregnated bearings made primarily from elemental copper,tin, lead, and graphite powders. The manufacturer may, at hisdiscretion, use prealloyed bronze powder in the mixed powder.1.2 This specification covers the following variables:1.2.1 GradesAvailable in three bronze base compo
4、sitionsidentifiable by different graphite contents and one leadedbronze grade.1.2.2 TypeGrades 1 and 2 are available in four typesdescribed by specific density ranges. Grade 3 is available intwo types and Grade 4 is available in one type.1.3 Bearings ordered to this specification will normally besiz
5、ed after sintering and will be impregnated with a lubricatingoil unless otherwise specified by the print.1.4 The values stated in either inch-pound or SI units are tobe regarded separately as standard. The values stated in eachsystem are not exact equivalents; therefore, each system shallbe used ind
6、ependently of the other. Combining values from thetwo systems may result in nonconformance with this specifi-cation.1.5 The following safety hazards caveat pertains only to thetest methods described in this specification. This standard doesnot purport to address all of the safety concerns, if any,as
7、sociated with its use. It is the responsibility of the user of thisstandard to establish appropriate safety and health practicesand determine the applicability of regulatory limitations priorto use.2. Referenced Documents2.1 ASTM Standards:2B 328 Test Method for Density, Oil Content, and Intercon-ne
8、cted Porosity of Sintered Metal Structural Parts andOil-Impregnated BearingsB 939 Test Method for Radial Crushing Strength, K, ofPowder Metallurgy (P/M), Bearings and Structural Mate-rialsE9 Test Methods of Compression Testing of Metallic Ma-terials at Room Temperature2.2 Government Standards:3MIL-P
9、RF-6085 Lubricating Oil: Instrument, Aircraft, LowVolatilityMIL-PRF-17331 Lubrication Oil: Steam Turbine and Gear,Moderate ServiceFED-STD-151 Metals Test Method2.3 MPIF Standard:4MPIF Standard 35 Materials Standards for P/M Self-Lubricating Bearings3. Ordering Information3.1 Orders for bearings unde
10、r this specification shall includethe following information:3.1.1 Dimensions and tolerances (Section 9),3.1.2 Grade and type (see Tables 1-5),3.1.3 Wet density specification (Table 2 and Table 3), and3.1.4 Oil type.4. Materials and Manufacture4.1 Sintered bronze bearings shall be made by molding orb
11、riquetting metal powder mixtures to the proper density. Thegreen bearing shall be sintered at a timetemperature relation-ship to produce a microstructure that is essentially alpha bronzeand contains no tin-rich phases visible at 3003. Sinteredbronze bearings are normally sized after sintering to mai
12、ntainthe dimensional characteristics required of the bearing. Aftersizing and inspection, they are impregnated with a lubricatingoil unless otherwise specified.1This specification is under the jurisdiction of ASTM Committee B09 on MetalPowders and Metal Powder Products and is the direct responsibili
13、ty of Subcom-mittee B09.04 on Bearings.Current edition approved Nov. 1, 2005. Published November 2005. Originallyapproved in 1966. Last previous edition approved in 2004 as B 438/B 438M 04.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servic
14、eastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 191115094, Attn: NPODS.4Available from Metal Powders Industries F
15、ederation (MPIF), 105 College RoadEast, Princeton, NJ 085406692, USA.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5. Chemical Composition5.1 The material shall conform to the requirements as to thechemical composition prescribed i
16、n Table 1.6. Physical Properties6.1 DensityThe density of bearings supplied impregnatedwith lubricant shall be within the limits prescribed in Table 2and Table 3, when determined in accordance with Test MethodB 328.6.2 Oil ContentOil content of bearings shall not be lessthan shown in Table 4 for eac
17、h grade and type when deter-mined in accordance with Test Method B 328.7. Mechanical Properties7.1 The manufacturer and purchaser shall agree on thenumber of sample bearings to be taken at random from each lotfor quantitative determination of mechanical properties bydestructive tests.7.2 Radial Crus
18、hing StrengthRadial crushing strength inpsi or Mpa is the mechanical property by which the strength ofoil-impregnated P/M bearing material is characterized andevaluated. It is determined by breaking plain, thin-walledbearings or hollow cylindrical test specimens under diametricalloading, following t
19、he procedure described in Test MethodB 939, and calculating the radial crushing strength accordingthe material strength formula contained herein.7.2.1 Plain sleeve bearings and thrust bearings are tested inthe oil-impregnated condition. For acceptance, the radial crush-ing strength, determined on th
20、e test bearings, shall not be lessthan the minimum strength specification value listed in Table 5for the grade and type of bearing material.7.2.2 Flanged oil-impregnated bearings shall be tested bycutting off the flange and crushing the body as a plain sleevebearing. For acceptance, the radial crush
21、ing strength so deter-mined shall meet the minimum material strength requirementsprescribed in Table 5. The testing procedure and materialstrength requirements of the flange shall be a matter ofagreement between manufacturer and purchaser.7.2.3 To evaluate spherical bearings or those of otherconfigu
22、ration, a number of sample parts from the lot shall firstbe machined to a right circular cylinder, measured, and thencrushed to determine the radial crushing strength of theoil-impregnated bearing material. This value shall not be lessthan the minimum radial crushing strength specified in Table 5for
23、 the grade and type of the material in the spherical bearing.7.3 Bearing Breaking LoadIf agreed to by the manufac-turer and the purchaser, an acceptance specification for theminimum bearing breaking load, Pmin, in lbf or N, may beestablished for any specific standard oil-impregnated bearing.This sim
24、plifies acceptance testing because the decision is nowbased solely upon reading the output of the testing machinewithout a need for further calculations. This acceptance pro-cedure can be very useful when evaluating multiple or repeatshipments of the same bearing.7.3.1 The minimum breaking load, Pmi
25、n, required for accep-tance of any specific plain sleeve or thrust bearing is calculatedusing the breaking load formula:Pmin5 K 3 L 3 t2/D t! (1)TABLE 1 Chemical Requirements (Composition, %)Element Grade 1 Grade 2 Grade 3 Grade 4Copper 87.290.5 85.790.0 82.888.3 80.988.0Tin 9.510.5 9.510.5 9.210.2
26、9.510.5Graphite 00.3 0.51.8 2.55.0 0.501.75Iron, max 1.0 1.0 1.0 1.0Total other elementsby difference, max1.0 1.0 1.0 0.5Lead 2.04.0Zinc, max 0.75Nickel, max 0.35Antimony, max 0.25NOTEGrade 4 to be used for special government needs.TABLE 2 Density Requirements (Oil Impregnated)Type Density, g/cm3Gra
27、des 1 and 2 1 5.86.2AGrades 1, 2, and 4 2 6.46.8Grades 1 and 2 3 6.87.2Grades 1 and 2 4 7.27.6AMaximum density limit of 6.2 g/cm3has been established on Type 1 to ensuremeeting an oil content of 27 % minimum. Satisfactory bearings can also beproduced between Type 1 and Type 2. These bearings have sl
28、ightly higherstrength constants and slightly lower oil content.TABLE 3 Density Requirements (Oil Impregnated)Type Density, g/cm3Grade 3 1 5.86.22 6.26.6TABLE 4 Oil Content (Oil Content, Volume %, Min)Type Grade 1 Grade 2 Grade 3 Grade 4127 5 1A.2 19 17 .B173 12 9 . .4 9 7 . .AAt 3 % graphite, Type 1
29、 will contain 14 % min oil content.BAt 3 % graphite, Type 2 will contain 8 % min oil content. At 5 % graphite, Type2 will contain only a minimal amount of oil.TABLE 5 Minimum Radial Crushing Strength for BronzeBearings (Oil-Impregnated)Grade Type Minimum StrengthBronzeCompositionWetDensityKg/cm3psi
30、MPaLow Graphite Bronze1 1 15 000 1001 2 26 000 1801 3 37 000 2601 4 40 000 280Medium Graphite Bronze2 1 13 000 902 2 23 000 1602 3 30 000 2102 4 34 000 230High Graphite Bronze3 1 10 000 703 2 15 000 100Leaded Bronze4 2 23 000 160B 438/B 438M 052where:Pmin= minimum bearing breaking load, lbf or N,K =
31、 radial crushing strength, psi or MPa,L = length of bearing, in. or mm,t = wall thickness (t = (D d)/2), in. or mm,D = outside diameter, in. or mm, andd = inside diameter, in. or mm.Use the minimum radial crushing strength value specified forthe grade and type oil-impregnated bearing material from T
32、able5 for K, use the actual D, d, and L dimensions of theas-received bearing and solve for Pmin. This calculated valuewill be the minimum acceptable breaking load for that specificplain bearing.7.3.2 The minimum acceptable breaking load for a specificflanged bearing shall be determined by first cutt
33、ing off theflange and measuring the D, d, and L of the body. Then, usingthe minimum radial crushing strength for the grade and type ofoil-impregnated bearing material from Table 5 for K in thebreaking load formula and the measured dimensions of thebody, a Pminvalue may be calculated. This will be th
34、eminimum bearing breaking load required for the body of thatspecific flanged bearing. The test procedure and breaking loadrequirements for the flange shall be a matter of agreementbetween purchaser and manufacturer.7.3.3 For acceptance testing of whole spherical bearings, aminimum bearing breaking l
35、oad specification, Pmin, may beestablished on a specific oil-impregnated bearing. First, theradial crushing strength is determined on that specific sphericalbearing machined to a right circular cylinder as in 7.2.3.Second, whole spherical bearings from the same lot arecrushed, keeping their axes hor
36、izontal, to determine the break-ing load of the whole bearing. Then, using the correlationformula, the specification for that whole spherical bearing iscalculated as follows:Pmin5 K 3 Pa/ Ka(2)where:Pmin= specification for the minimum bearing breakingload of a specific whole spherical bearing, lbf o
37、r N,Ka= radial crushing strength of machined test sphericalbearings according to 7.2.3, psi or MPa,K = radial crushing strength for the grade and type ofbearing material from Table 5, psi or MPa, andPa= breaking load of whole test spherical bearings, lbfor N.8. Chemical Analysis8.1 If required by pu
38、rchase agreement, one sample forchemical analysis shall be taken from each lot.Arepresentativesample of chips may be obtained by milling, drilling, filing, orcrushing a bearing with clean dry tools without lubrication. Toobtain oil-free chips, the parts selected for test shall have theoil extracted
39、in accordance with Test Method B 328 if neces-sary.8.2 The chemical analysis shall be made in accordance withthe methods prescribed in Vol 03.05 of the Annual Book ofASTM Standards or by any other method agreed upon betweenthe manufacturer and the purchaser.9. Dimensions and Tolerances9.1 Permissibl
40、e variations in dimensions shall be within thelimits specified on the drawings describing the bearings ac-companying the order or shall be within the limits specified onthe order.10. Workmanship, Finish, and Appearance10.1 Bearings shall be uniform in composition, clean, andconform to applicable dra
41、wings.11. Sampling11.1 LotUnless otherwise specified, a lot shall consist ofparts of the same form and dimensions made from powders ofthe same composition, formed and sintered under the sameconditions, and submitted for inspection at one time.12. Inspection12.1 Unless otherwise specified, inspection
42、 of parts sup-plied on contract shall be made by the purchaser at thedestination.13. Rejection13.1 Parts that fail to conform to the requirements of thisspecification may be rejected. Rejection should be reported tothe producer or supplier promptly and in writing.14. Certification14.1 When specified
43、 in the purchase order or contract, aproducers certification shall be furnished to the purchaser thatthe parts were manufactured, sampled, tested, and inspected inaccordance with this specification and have been found to meetthe requirements. When specified in the purchase order orcontract, a report
44、 of the test results shall be furnished.14.2 The purchase order must specify whether or not thecertification includes chemistry.14.3 Upon request of the purchaser in the contract or order,the certification of an independent third party indicatingconformance to the requirements of this specification
45、may beconsidered.15. Supplementary Requirements15.1 For some materials, supplementary requirements maybe specified. Usually these apply only when specified by thepurchaser in the inquiry, contract, or order. These supplemen-tary requirements shall appear separately.15.2 Special Government Requiremen
46、tsRequirementsthat are special to government needs are listed in 15.2.1through 15.2.9.15.2.1 Materials shall conform to Table 1, Grade 4. Con-tractor shall furnish a percent composition analysis on anoil-free basis for each lot showing the percentage for eachelement as specified in Table 1. Bearing
47、shall conform to thisspecification and supporting military specification as appli-cable.15.2.2 High-grade non-gumming petroleum lubricants, suchas MIL-PRF-6085, MIL-PRF-17331 (Military Symbol2190TEP), or as specified on referenced military standardspecification sheets shall be used to impregnate the
48、 bearings.B 438/B 438M 05315.2.3 When specified, a first-article inspection shall beperformed on bearings. Four samples shall be made availablefor first-article inspection and tested for chemical require-ments, density, porosity, radial crushing strength, oil excretion,and dimensional characteristic
49、s as specified herein, TestMethod B 328, FED-STD-151, or in an otherwise specifieddocument. Any defect or failure shall be cause for rejection ofthe lot. Waivers for minor defects may be addressed to thecontracting officer.15.2.4 When procured from a contractor versus the actualmanufacturer, a certificate of quality conformance (COQC)supplied by the manufacturer of the bearing may be furnishedin lieu of actual performance of such testing by the contractor,provided lot identity has been maintained and can be demon-strated to the Government. The
