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ASTM B702-93(R2019) pdf free download

ASTM B702-93(R2019) pdf free download.Standard Specification for Copper-Tungsten Electrical Contact Material
1. Scope
1.1 This specification covers electrical contact components made from copper tungsten by powder metallurgical proce- dures. 1.2 This specification covers compositions within the cop- per tungsten system normally specified by users of contacts. 1.3 The values stated in inch-pound units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 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 become familiar with all hazards including those identified in the appropriate Data Safety Sheet (SDS) for this product/material as provided by the manufacturer, to establish appropriate safety, health, and environmental practices, and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accor- dance with internationally recognized principles on standard- ization established in the Decision on Principles for the Development of International Standards, Guides and Recom- mendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
3. Significance and Use
3.1 Proprietary methods for manufacture of these materials vary significantly among suppliers and these methods influence This specification is under the jurisdiction of ASTM Committee B02 on Nonferrous Metals and Alloys and is the direct responsibility of Subcommittee B02.05 on Precious Metals and Electrical Contact Materials. Current edition approved Nov. 1, 2019. Published November 2019. Originally approved in 1982. Last previous edition approved in 2015 as B702 – 93 (2015). DOI: 10.1520/B0702-93R19. For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards volume information, refer to the standard’s Document Summary page on the ASTM website. The last approved version of this historical standard is referenced on www.astm.org. such properties as arc erosion, contact resistance, and tendency to weld in service. Since the performance of contacts in a device depends on numerous factors outside the contact itself (opening speed, closing speed, contact pressure, contact bounce, environmental variations, assembly technique and variations, etc.) this specification cannot ensure performance control in the application. As part of the qualification on initial samples it is recommended that the user functionally electri- cally test the materials for all devices applicable to the material’s use. This specification will provide a means for the contact manufacturer and contact user to reach agreement on the details of material to be supplied for a specified use and reasonable assurance that future lots will be similar in proper- ties and microstructure to the initial test or sample contacts supplied.
4. Ordering Information
4.1 Orders for this material under this specification shall include the following information: 4.1.1 Dimensions (see Section 8), 4.1.2 Chemical composition (see reference tables in Related Material as possible guideline), 4.1.3 Physical properties (see Section 6 and reference tables as guideline), 4.1.4 Certification (see Section 11), and 4.1.5 Other features as agreed upon between the vendor and the user.
5. Chemical Requirements
5.1 The material shall conform to composition limits as agreed upon between the manufacturer and the user. 5.2 The chemical analysis shall be made in accordance with the methods prescribed in the newest edition of Annual Book of ASTM Standards, or by any other approved method agreed upon between the manufacturer and the purchaser.
9. Sampling and Inspection
9.1 Lot—Unless otherwise specified, a lot shall consist of parts of the same form, and dimensions, made of powders of the same particle size range and composition, processed under the same conditions, and submitted for inspection at one time. 9.2 Chemical Analysis—At least one sample for chemical analysis shall be taken from each lot. A representative sample of chips may be obtained by milling, drilling, or crushing at least two pieces with dry tools, without lubrication. In order to obtain oil-free chips, the parts selected for test shall have the oil extracted in accordance with Test Method B328, if neces- sary. 9.2.1 These specification limits do not preclude the possible presence of other unnamed elements, impurities or additives. Analysis shall be regularly made only for the minor elements listed in the table. However, if a user knows of elements that might be detrimental to their application or has other reasons for requiring analysis for specific elements, then agreement between manufacturer and purchaser for both limits and methods of analysis should be required for elements not specified.

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