ASTM B438 PDF
ASTM B Standard Specification for Bronze-Base Powder Metallurgy (PM) Bearings (Oil-Impregnated). ASTM – B, Grade 1, Type II; MPIF – CTK26; Military – MIL-BD, Type I, Grade I (this spec only applies to Bushings & Washers. It must be requested. ASTM – B, Grade 1, Type II. Military – MIL-BD, Type I, Comp. A. MPIF – CTK Heavy industry uses Sintered Bronze as machinery components.
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Grade 3 is available in two types and Grade 4 is available in one type.
After sizing and inspection, they are impregnated with a lubricating oil unless otherwise speci? These supplementary requirements shall appear separately. Any defect or failure shall be cause for rejection of the lot. Those additional government requirements that only apply to military bearings are listed in the Supplementary Requirements section of this specification. Dimensions and Tolerances 9. Special Tolerancein.
An acceptance specification for the minimum bearing breaking load may be established for any specific standard oil-impregnated bearing. Satisfactory bearings can also be produced between Type 1 and Type 2. The astk of a sintered bearing is essentially defined by the tool design and its manufacture.
Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.
Oil Impregnated Sintered Bronze – plate, cored bar, solid bar & bushings
Plating, coating, deburring, welding, furnace brazing, heat treating, and steam treating are among the secondary operations that are used successfully in the process of fabricating finished PM parts. Repeated start-stop operation, oscillatory or reciprocating motion, high speeds, shock loads, and temperature extremes tend to decrease permissible loads. The manufacturer may, at his discretion, use prealloyed bronze powder in the mixed powder. Sintered bronze bearings are normally sized after sintering to maintain the dimensional characteristics required of the bearing.
The dash numbers remain unchanged from the MS 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. Sintered bronze bearings shall be made by molding or briquetting metal powder mixtures to the proper density.
Satisfactory bearings can also be produced between Type 1 and Type 2. The values stated in each system are not exact equivalents; therefore, each system shall be used independently of the other.
Current edition approved Nov. Combining values from the two systems may result in nonconformance with this speci? For acceptance, the radial crushing strength so determined shall meet the minimum material strength requirements prescribed in Table 5.
Then, using the correlation formula, the speci? Originally approved in Waivers for minor defects may be addressed to the contracting officer. The maximum running clearances will automatically be held within good design practice asym average conditions. The viscosity should be speci?
These bearings have slightly higher strength constants and slightly lower oil content. This standard does not purport to address all of the safety concerns, if any, associated with its use.
Chemical analysis shall be made for each representative sample of chips, which may be obtained b4438 milling, drilling, filing, or crushing a bearing with clean dry tools without lubrication. If necessary, a sintered PM component can be finished or treated just like any other metal component to achieve desired characteristics—corrosion resistance, improved strength and hardness, surface wear resistance, edge-sharpness relief, porosity sealing, and control of size and surface finish.
If you feel that your comments have not received a fair hearing you should make your views known to the ASTM Committee on Standards, at the address shown below. It is determined by breaking plain, b348 bearings or hollow cylindrical test specimens under diametrical loading, following the procedure described in Test Method Band calculating the radial crushing strength according the material strength formula contained herein.
Dimensions qstm Tolerances 9.
Oil Impregnated Sintered Bronze / SAE Products
Oil content of bearings shall not be less than the prescribed value for each grade and type of material.
Last previous edition approved in as B — 00a. The contractor may use their own or any other suitable facility for the performance of testing and inspection, unless an exception is stated. The part combinations are only limited to the design concept. The green bearing shall be sintered at a time—temperature relationship to produce a xstm that is essentially alpha bronze and contains no tin-rich phases visible at This standard has been approved for use by agencies of the B43 of Defense.
Special tolerances should not be speci? Since compaction occurs in the vertical direction, using only top and bottom motions, part lengths in the pressing direction are limited.
The Government qstm the right to perform an inspection set forth herein to assure supplies and sources conform to the prescribed requirements. Each section shall meet the minimum strength requirements prescribed in Table 5.
Users of this standard astj expressly advised that determination of the validity of any such patent rights, and the risk of infringement of such rights, are entirely their own responsibility.