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ASTM B438 - 21
Standard Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated)
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Abstract
This specification covers sintered bronze, oil-impregnated bearings made primarily from elemental copper, tin, lead, and graphite powders. This specification covers the following variables: Grades (available in three bronze base compositions identifiable by different graphite contents and one leaded bronze grade) and Type (Grades 1 and 2 are available in four types described by specific density ranges. Grade 3 is available in two types and Grade 4 is available in one type). Sintered bronze bearings shall be made by molding or briquetting metal powder mixtures to the proper density. The material shall conform to the required chemical composition for copper, tin, graphite, iron, lead, zinc, nickel, and antimony. The density of bearings supplied impregnated with lubricant shall be within the prescribed limits. Oil content of bearings shall not be less than the prescribed value for each grade and type of material. The material of different grades and types shall conform to the prescribed radial crushing strength requirements. An acceptance specification for the minimum bearing breaking load may be established for any specific standard oil-impregnated bearing. Chemical analysis shall be made for each representative sample of chips, which may be obtained by milling, drilling, filing, or crushing a bearing with clean dry tools without lubrication.
This abstract is a brief summary of the referenced standard. It is informational only and not an official part of the standard; the full text of the standard itself must be referred to for its use and application. ASTM does not give any warranty express or implied or make any representation that the contents of this abstract are accurate, complete or up to date.
1. Scope
1.1 This specification covers porous metallic sleeve, flange, thrust, and spherical bronze-base bearings that are produced from mixed metal powders utilizing powder metallurgy (PM) technology and then impregnated with oil to supply operating lubrication.
1.2 Included are the specifications for the chemical, physical, and mechanical requirements of those bronze-base PM materials that have been developed and standardized specifically for use in the manufacture of these self-lubricating bearings.
1.3 This specification is applicable to the purchase of bronze-base bearings (oil-impregnated) that were formerly covered by military specifications and are intended for government or military applications. Those additional government requirements that only apply to military bearings are listed in the Supplementary Requirements section of this specification.
1.4 This specification accompanies Specification B439 that covers the requirements for Iron-Base Powder Metallurgy (PM) Bearings, (Oil-Impregnated).
1.5 Typical applications for bronze-base bearings are listed in Appendix X1.
1.6 Bearing dimensional tolerance data are shown in Appendix X2, while engineering information regarding installation and operating parameters of PM bearings is included in Appendix X3. Additional useful information on self-lubricating bearings can be found in MPIF Standard 35, ISO 5755 and the technical literature.2
1.7 With the exception of the values for density and the mass used to determine density, for which the use of the gram per cubic centimetre (g/cm3) and gram (g) units is the industry standard, the values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.8 The following safety hazards caveat pertains only to the test methods described in this specification. This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.
1.9 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.
ASTM Standards
B243 Terminology of Powder Metallurgy
B439 Specification for Iron-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated)
B939 Test Method for Radial Crushing Strength, K, of Powder Metallurgy (PM) Bearings and Structural Materials
B946 Test Method for Surface Finish of Powder Metallurgy (PM) Products
B962 Test Methods for Density of Compacted or Sintered Powder Metallurgy (PM) Products Using Archimedes Principle
B963 Test Methods for Oil Content, Oil-Impregnation Efficiency, and Surface-Connected Porosity of Sintered Powder Metallurgy (PM) Products Using Archimedes Principle
E9 Test Methods of Compression Testing of Metallic Materials at Room Temperature
E29 Practice for Using Significant Digits in Test Data to Determine Conformance with Specifications
E1019 Test Methods for Determination of Carbon, Sulfur, Nitrogen, and Oxygen in Steel, Iron, Nickel, and Cobalt Alloys by Various Combustion and Inert Gas Fusion Techniques
ISO Standards
ISO 2795 ISO 5755 Sintered Metal Materials - SpecificationsGovernment Standards
MIL-PRF-17331 Lubrication Oil, Steam Turbine and Gear, Moderate Service MIL-PRF-6085 Lubricating Oil: Instrument, Aircraft, Low Volatility QPL-17331 Lubricating Oil, Steam Turbine and Gear, Moderate Service QPL-6085 Lubricating Oil Instrument, Aircraft, Low VolatilityICS Code
ICS Number Code 21.100.01 (Bearings in general)
Referencing This Standard
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DOI: 10.1520/B0438-21
Citation Format
ASTM B438-21, Standard Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated), ASTM International, West Conshohocken, PA, 2021, www.astm.org
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