1、SAE Technical Standards Board Rules provide that: “This report is published by SAE to advance the state of technical and engineering sciences. The use of this report is entirelyvoluntary, and its applicability and suitability for any particular use, including any patent infringement arising therefro
2、m, is the sole responsibility of the user.”SAE reviews each technical report at least every five years at which time it may be reaffirmed, revised, or cancelled. SAE invites your written comments and suggestions.Copyright 2001 Society of Automotive Engineers, Inc.All rights reserved. Printed in U.S.
3、A.QUESTIONS REGARDING THIS DOCUMENT: (724) 772-7161 FAX: (724) 776-0243TO PLACE A DOCUMENT ORDER: (724) 776-4970 FAX: (724) 776-0790SAE WEB ADDRESS: http:/www.sae.org400 Commonwealth Drive, Warrendale, PA 15096-0001AEROSPACE MATERIAL SPECIFICATIONAMS 7268CIssued NOV 1969Revised OCT 1994Reaffirmed OC
4、T 2001Superseding AMS 7268BRings, Sealing, Silicone RubberLow Compression Set, Non-Oil Resistant65 - 751. SCOPE:1.1 Form: This specification covers a low-compression-set, non-oil-resistant silicone rubber in the form of molded rings.1.2 Application: These rings have been used typically for sealing r
5、ings in contact with air from -55 to +200 C (-67 to +392 F), but usage is not limited to such applications. These rings are not intended for service involving exposure to petroleum products and are not required to be tested for compatibility with such products. 1.2.1 These rings have excellent resis
6、tance to compression set at the expense of tensile strength, elongation, and tear resistance and are resistant to deterioration by ozone, smog, and weathering.1.3 Safety-Hazardous Materials: While the materials, methods, applications, and processes described or referenced in this specification may i
7、nvolve the use of hazardous materials, this specification does not address the hazards which may be involved in such use. It is the sole responsibility of the user to ensure familiarity with the safe and proper use of any hazardous materials and to take necessary precautionary measures to ensure the
8、 health and safety of all personnel involved. 2. APPLICABLE DOCUMENTS: The following publications form a part of this specification to the extent specified herein. The latest issue of SAE publications shall apply. The applicable issue of other publications shall be the issue in effect on the date of
9、 the purchase order.AMS 7268C SAE AMS 7268C- 2 -2.1 SAE Publications: Available from SAE, 400 Commonwealth Drive, Warrendale, PA 15096-0001.AMS 2817 Packaging and Identification, Preformed PackingsAS568 Aerospace Size Standard for O-RingsAS871 Manufacturing and Inspection Standards for Preformed Pac
10、kings (O-Rings)AIR851 O-Ring Tension Testing Calculations2.2 ASTM Publications: Available from ASTM, 1916 Race Street, Philadelphia, PA 19103-1187.ASTM D 624 Tear Strength of Conventional Vulcanized Rubber and Thermoplastic ElastomerASTM D 1414 Rubber O-RingsASTM D 3182 Rubber - Materials, Equipment
11、, and Procedures for Mixing Standard Compounds and Preparing Standard Vulcanized Sheets3. TECHNICAL REQUIREMENTS: 3.1 Material: Shall be a compound, based on a silicone elastomer, suitably cured to produce sealing rings meeting the requirements of 3.2.3.2 Properties: Rings shall conform to requireme
12、nts shown in Table 1, except as otherwise specified herein. For tension testing rings smaller than can be tested using 1/2 inch (12.7 mm) diameter rotating spools, spools of reduced diameter, in 1/8 inch (3.2 mm) increments, shall be used. Spool mounts shall be rotated 180degrees relative to each ot
13、her when necessary to allow closing to the unelongated length of the ring (See AIR851).AMS 7268C SAE AMS 7268C- 3 -3.3 QUALITY: Rings, as received by purchaser, shall be uniform in quality and condition, smooth, and free from chalky spots, as free from foreign materials as commercially practicable,
14、and free from imperfections detrimental to usage of the rings. Surface imperfections shall be no greater than permitted by AS871.TABLE 1 - PropertiesParagraph Property Requirement Test Method3.2.1 Hardness, Durometer “A“ or equivalent3.2.2 Tensile Strength, min3.2.3 Elongation, min3.2.4 Tear Resista
15、nce, min3.2.5 Specific Gravity3.2.6 Dry Heat Resistance:3.2.6.1 Hardness Change, Durometer “A“or equivalent3.2.6.2 Tensile Strength Change, max3.2.6.3 Elongation Change, max3.2.7 Compression SetPercent of Original Deflection, maxRing Cross Section Diameter0.066 to 0.110 inch (1.68 to 2.79 mm), inclO
16、ver 0.110 inch (2.79 mm)3.2.8 Low-Temperature Resistance:Temperature RetractionTR10 point, max70 5800 psi(5.52 MPa)125%50 pounds force/inch(8756 N/m)Preproduction Value0.03-10 to + 10-20%-35%2520-42 C (-44 F)ASTM D 1414, orASTM D 3182 when permitted by purchaserASTM D 1414ASTM D 1414ASTM D 624 on sp
17、ecimens cut with Die B from ASTM D 3182ASTM D 1414ASTM D 1414225 C 3(437 F 5)70 hours 0.5ASTM D 1414175 C 3(347 F 5)22 hours 0.25ASTM D 1414AMS 7268C SAE AMS 7268C- 4 -3.4 Sizes and Tolerances: Shall be as specified on the drawing. Inspection for conformance to dimensional requirements shall be made
18、 in accordance with AS871. Standard sizes are as shown in AS568.4. QUALITY ASSURANCE PROVISIONS: 4.1 Responsibility for Inspection: The manufacturer of rings shall supply all samples for required tests and shall be responsible for all required tests. Purchaser reserves the right to sample and to per
19、form any confirmatory testing deemed necessary to ensure that the rings conform to the requirements of this specification.4.2 Classification of Tests: 4.2.1 Acceptance Tests: Tests for requirements shown in Table 2 are acceptance tests and shall be performed on each lot:4.2.2 Preproduction Tests: Te
20、sts for all technical requirements are preproduction tests and shall be performed prior to or on the first-article shipment of rings by a manufacturer, when a change in ingredients and/or processing requires reapproval as in 4.4.2, and when purchaser deems confirmatory testing to be required.4.2.2.1
21、 For direct U.S. Military procurement, substantiating test data and, when requested, preproduction test material shall be submitted to the cognizant agency as directed by the procuring activity, contracting officer, or request for procurement.4.3 Sampling and Testing: Shall be as follows:TABLE 2 - A
22、cceptance TestsRequirement Paragraph ReferenceHardness, as received Tensile Strength, as receivedElongation, as received Specific Gravity, as receivedCompression Set 3.2.13.2.23.2.33.2.53.2.7AMS 7268C SAE AMS 7268C- 5 -4.3.1 For Acceptance Tests: Sufficient rings taken at random from each lot and, w
23、hen required, ASTM D 3182 standard sheets of equivalent cure from the same batch of compound, shall be used to perform all required tests; the number of determinations for each requirement shall be as specified in the applicable test procedure or, if not specified therein, not less than three. For r
24、ings smaller than AS568-10 dimensions, AS568-218 rings from the same batch and equivalent cure shall be used.4.3.1.1 A lot shall be all rings of the same size from the same batch of compound and presented for manufacturers inspection at one time.4.3.1.2 A batch shall be the quantity of compound run
25、through a mill or mixer at one time.4.3.1.3 A statistical sampling plan, acceptable to purchaser, may be used in lieu of sampling as in 4.3.1 and the report of 4.5 shall state that such plan was used.4.3.2 For Preproduction Tests: Shall be acceptable to purchaser.4.4 Approval: 4.4.1 Sample rings, an
26、d standard sheets when required, shall be approved by purchaser before rings for production use are supplied, unless such approval be waived by purchaser. Results of tests on production rings shall be essentially equivalent to those on the approved samples.4.4.2 Manufacturer shall use ingredients, m
27、anufacturing procedures, processes, and methods of inspection on productions rings which are essentially the same as those used on the approved sample. If necessary to make any change in ingredients, in type of equipment for processing, or in manufacturing procedures, manufacturer shall submit for r
28、eapproval a statement of the proposed changes in ingredients and/or processing and, when requested, sample rings and standard sheets. Production rings made by the revised procedure shall not be shipped prior to receipt of reapproval.4.5 Reports: The supplier of rings shall furnish with each shipment
29、 a report showing the results of tests to determine conformance to the acceptance test requirements and stating that the rings conform to the other technical requirements. This report shall include the purchase order number, lot number, AMS 7268C, manufacturers identification, part number, and quant
30、ity.4.6 Resampling and Retesting: If any specimen used in the above tests fails to meet the specified requirements, disposition of the rings may be based on the results of testing three additional specimens for each original nonconforming specimen. Failure of any retest specimen to meet the specifie
31、d requirements shall be cause for rejection of the rings represented. Results of all tests shall be reported.AMS 7268C SAE AMS 7268C- 6 -5. PREPARATION FOR DELIVERY: 5.1 Packaging and Marking: Shall be in accordance with AMS 2817.5.1.1 A lot of rings may be packaged in small quantities and delivered
32、 under the same basic lot approval provided lot identification is maintained.6. ACKNOWLEDGMENT: A supplier shall mention this specification number and its revision letter in all quotations and when acknowledging purchase orders.7. REJECTIONS: Rings not conforming to this specification, or to modific
33、ations authorized by purchaser, will be subject to rejection.8. NOTES: 8.1 A change bar ( l ) located in the left margin is for the convenience of the user in locating areas where technical revisions, not editorial changes, have been made to the previous issue of this specification. An (R) symbol to
34、 the left of the document title indicates a complete revision of the specification, including technical revisions. Change bars and (R) are not used in original publications, nor in specifications that contain editorial changes only.8.2 Dimensions and properties in inch/pound units and the Celsius te
35、mperatures are primary; dimensions and properties in SI units and the Fahrenheit temperatures are shown as the approximate equivalents of the primary units and are presented only for information.8.3 For direct U.S. Military procurement, purchase documents should specify not less than the following:T
36、itle, number, and date of this specificationSize or part number of rings desiredQuantity of rings desiredLevel A packaging, if required (See AMS 2817).8.4 Rings meetings the requirements of this specification have been classified under Federal Supply Classification (FSC) 5330.PREPARED UNDER THE JURISDICTION OF AMS COMMITTEE “CE“
