1、MILITARY SPECIFICATION MOUNTING BASES, FLEXIBLE PLASTICFOAM This specification has been approved by the Bureau of Naval Weapons, Department of the Navy 1. SCOPE 1.1 Scope - This specification covers the design and performance of mounting bases using flexible plastic foam to absorb shock and vibratio
2、n energy. 2. APPLICABLE DOCUMENTS 2.1 General - The documents listed in 6.5 of the issue in effect on the date of invitation for bids form a part of this specification to the extent specified herein. 3. REQUIREMENTS 3.1 Preproduction - This specification makes provision for preproduction testing. 3.
3、2 Materials - In the selection of materials, fulfillment of major design and performance objectives shall be the prime consideration. 3.2.1 Plastic Foam - The plastic foam used for the resilient medium for shock and vibration energy absorption shall be in accordance with MIL-F-8133L See 6.0. 3.2.2 C
4、orrosion Resistance - All metals shall be of corrosion-resistant types or shall be processed to resist corrosion and be entirely adequate for the intended purpose. 3.2.3 Dissimilar Metals - Protection of dissimilar metal combinations shall be in accordance with MIL-STD-454, Requirement 16. 3.2.4 Fin
5、ishes - Parts fabricated from aluminum alloys 3003, 5052, 6053, 6061, 6063, or 7072 shall be cleaned with a deoxidizing solution other than Caustic dip and may be used with or without other surface treatment. Other alloys shall be anodized in accordance with MIL-A- 8625. - I FSC-5340 4 Provided by I
6、HSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-= MIL-M- 81288 (WP) 3.2.5 Adhesives - The adhesive used to secure the foam shall be Goodyear Aircraft Company, Pliobond #30 or approved equivalent. Preparation of the surfaces and the bonding procedure recommended b
7、y the adhesive manufacturer shall be followed. 3.3 Design and Construction - The mounting base shall conform with all the requirements for design, construction and workman- ship, specified herein. 3.3.1 Total Weight - The total weight of the mounting base shall be the minimum required to pass the te
8、sts specified herein consistent with good design. 3.3.2 Mechanical Interference - The design must minimize projections of the equipment and rack below the top surface of the foam. See 3.4.1.3(2). 3.3.3 Safety Wiring - Safety wiring, passing through holes provided for the purpose in the thumb nuts or
9、 wing nuts of the fastener assembly and in the mounting base, shall be used to prevent loosening thereof under vibration. Safety wiring may be eliminated if suitable automatic locking devices are used. proven adequate to the satisfaction of the U. S. Naval Air Development Center (NAVAIRDEVCEN) . Suc
10、h devices, if used, must be - 3.3.4 Bonding Jumpers - Bonding jumpers shall be provided for an electrical conducting path around the plastic foam isolation element and other mating parts. The bonding jumpers shall be braided beryllium copper, or phosphor-bronze silver-plated, or cadmium-plated metal
11、 strip having a width-to-length ratio of not less than 1 to 5. A minimum of two bonding jumpers, preferably located externally at diagonally opposite corners of the mounting base, shall be provided. Bonding jumpers shall be of such length and resilience so as not to have any effect on the natural re
12、sonance of the mounting system. 3.3.5 Distribution of Load - The total load (including cables and connectors) shall be uniformly distributed over the entire foam pad. Compression of foam shall be no more than 10% of its free height. by the desired natural frequency and satisfactory shock isolation,
13、but in no instance shall it be less than 0.1 lb. per square inch nor greater than 0.5 lb. per square inch. Applied weight per square inch of foam shall be determined Foam - The foam shall be applied to the metal sur- - 3.3.6 -faces of the mounting base in a manner such that bulging or shrinking The
14、outer edge of the foam shall not be closer than does not result. 2 . r. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-M-81288 53 7793306 OLL0127 2 MIL-M- 81288(WP) 1/16 inch from the radii of all curved surfaces such as the top and bottom plate
15、. All external surfaces of the foam shall be smooth and continuous. 3.3.6.1 Sealing - All outer surfaces of the foam shall not be coated or sealed in any way. 3.3.7 Motion Limiting Devices - Motion limiting devices shall not be used. 3.4 Performance - 3.4.1 Static Parameters - 3.4.1.1 Loaded Height
16、- When the mounted unit is examined as specified in paragraph 4.5.2.1, the maximum loaded height shall be 1.563 inches. The total load (including connectors and cables) shall be uniformly distributed over the entire foam pad in such a manner that the mounted unit is parallel to its mounting surface
17、11/16 inch. 3.4.1.2 Electrical Bonding - When measured as specified in paragraph 4.5.2.2, the d-c resistance shall not exceed six milliohms. 3.4.1.3 Sway Space - When tested as specified in paragraph 4.5.2.3, the mounted unit shall meet the following requirements: (1) No part of the equipment or moc
18、k-up shall move from its normal position by more than the amount shown on Figure 1. (2) There shall be no contact between non-resilient members. (3) There shall be no failure of, or damage to, the mounting base. 3.4.2 Dynamic Parameters - 3 .f: .2.1 Vibration - (see paragraph 4.5.3.1). 3.4.2.1.1 Iso
19、lation Efficiency - When the mounted unit is tested as specified in paragraph 4.5.3.1.1, the transmissibility along each axis shall not exceed that shown on Figure 2. 3.4.2.1.2 Fatigue - When the mounted unit is tested as specified in paragraph 4.5.3.1.2, there shall be no evidence of mounting base
20、Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-damage, nor shall there be repetitive bouncing between mounting base members normally not in contact. Transmissibility at resonance shall not exceed five. 3.4.2.1.3 Isolation Efficiency After Fatigue (S
21、ee Paragraph 4.5.3.1.3) - The requirements of paragraph 3.4.2.1.1 shall apply. MIL-M-81288 53 W 7779706 OLL0130 7 W 3.4.2.2 - Shock - (See Paragraph 4.5.3.2). 3.4.2.2.1 Service Shock - When the-mounted unit is tested as specified in paragraph 4.5.3.2.1, there shall be no tearing of foam, evidence of
22、 adhesive failure, bending or distortion. 3.4.2.2.2 Shock Transmissibility - When the mounted unit is tested as specified in paragraph 4.5.3.2.2, the shock transmissibility shall not exceed 90 per cent. 3.4.2.2.3 Crash Safety - When the mounted unit is tested as specified in paragraph 4.5.3.2.3, tea
23、ring of the foam and distortion of the sheet metal shall be permitted, but the mockup must remain captive. 3.4.2.2.4 Integrity - When the mounted unit is tested as specified in paragraph 4.5.3.2.4, tearing of the foam and distortion of the sheet metal shall be permitted. However, the mock-up must re
24、main captive, and there shall be no evidence that the adhesive is failing. 3.5 Standard Conditions - The following conditions shall be used to establish normal performance characteristics under standard conditions and for making laboratory tests: Temperature Alt it ude Vibration Humid it y Room Ambi
25、ent (25 OC !5C) Normal Ground None Room Ambient up to 90% R.H. 3.6 Service Conditions - The mounting base shall operate satisfactorily under any of the environmental service conditions or reasonable combination of these conditions as specified in Specification MIL-E-5400 for Class 2 equipment. 3.7 D
26、esign Data - No data is required by this specifica- tion (other than reports accompanying samples submitted for testing covering the results.of the contractor tests) or by applicable documents, unless specified in 3.8 nameplates shall be - - the contract or order (See paragraph 6.4). Nomenclature an
27、d Nameplates - Nonenchtua ad in accordance with IIIL-N-1$307. 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-4. QUALITY ASSURANCE PROVISIONS 4.1 Responsibility for Inspection - Unless otherwise specified in the contract or purchase order, the supp
28、lier is respon- sible for the performance of all inspection requirements as specified herein. Except as otherwise specified, the supplier may utilize his own facilities or any commercial laboratory acceptable to the Govern- ment. The Government reserves the right to perform any of the inspections se
29、t forth in the specification where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements. 4.1.1 Test Equipment and Inspection Facilities - Test equipment and inspection facilities shall be of sufficient accuracy, quality and quantity to permit perfo
30、rmance of the required tests. The manufacturer shall establish adequate calibration of test equip- ment to the satisfaction of the Government. 4.1.2 Classification of Tests - Items covered by this specification shall be subjected to the following tests to determine compliance with all applicable req
31、uirements: (1) Preproduction Tests (2) Initial Production Tests (3) Acceptance Tests 4. . 2 Preproduction Tests - Preproduction tests shall be made on one nlounting base representative of the production mounting base to be supplied under the contract. Preproduction tests shall be accomplished under
32、the responsibility of the contractor and shall be conducted in accordance with the procedures set forth in paragraph 4.2.2. advised when tests are to be conducted so that a representative may be designated to witness or supervise the tests when so desired. Contractors not having adequate facilities
33、to conduct all required tests shall obtain the services of a commercial testing laboratory acceptable- to the Government. The government inspectors and the procuring activity shall be 4.2.1 Preproduction Test Data - The contractor shall submit all data collected in conducting these tests to NAVAIRDE
34、KEN for review and approval. 1.2.2 Scope of Tests - Preproduction tests shall consist of all tests of this specification. 4.2.3 Preproduction Approval - Approval of the preproduction Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,- MIL-M-L2B 53 W 779
35、7706 OLL0132 2 W - sample shall be by NAVAIRDEVCEN upon satisfactory completion of all tests. No production mounting base shall be delivered prior to the approval of the preproduction sample. mounting base prior to the approval of the preproduction sample is at the contractors own risk. retained by
36、the contractor for his use in the fabrication and testing of mounting bases to be submitted for acceptance. The preproduction sample shall not be considered as one of the mounting bases under the contract. Prefabrication of a production The approved preproduction sample shall be 4.2.4 Production Mou
37、ntinp Bases - Mounting bases supplied under the contract shall in all respects, including design, construction, workmanship, performance and quality, be equivalent to the approved preproduction sample. Each mounting base shall be capable of success- fully passing the same tests as imposed on the pre
38、production sample. Evidence of non-compliance with the above shall constitute cause for rejection and for mounting bases already accepted by the Government, it shall be the obligation of the contractor to make necessary corrections as approved by the procuring activity. 4.3 Initial Production Tests
39、- One of the first ten production mounting bases shall be selected and sent at the contractors expense to NAVAIRDEVCEN. This mounting base shall be selected by the procuring activity after the mounting base has successfully passed all individual tests. The preproduction sample shall not be selected
40、for this test. 4.3.1 to any and all tests which NAVAIRDEVCEN deems necessary to assure that the production sample is equivalent to the previously approved prepro- duction sample in design, construction, workmanship, performance and quality and that it meets all applicable requirements. Scope of Test
41、s - This mounting base may be subjected 4.3.2 Initial Production Sample Approval - Approval of the Initial Production Sample shall be by NAVAIRDEVCEN upon satisfactory completion of all tests. Any design, material or performance defect made evident during this test shll be corrected by the contracto
42、r to the satisfaction of NAVAIRDEVCEN. Failure of the Initial Production Sample to pass any of the tests shall be cause for deliveries of mounting bases under the contract to cease until proper corrective action is approved and accomplished. Corrective action shall also be accomplished on mounting b
43、ases previously accepted when requested by the procuring activity. 4.3.3 Reconditioning of Initial Production Test Sample - On completion of the initial production test, the sample may be reworked 6 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-by
44、the contractor replacing all worn or damaged items. the contractor may submit the mounting base to NAVAIRDEVCEN for examination and approval prior to acceptance for delivery on the contract. After reworking, 4.4 Acceptance Tests - The contractor shall furnish all samples and shall be responsible for
45、 accomplishing the acceptance tests. All inspection and testing shall be under the-supervision of the government inspector. Contractors not having testing facilities satisfactory to the procuring activity shall engage the service of a comercial testing laboratory acceptable to the procuring activity
46、. The contractor shall furnish test reports showing quantitative results for all acceptance tests to NAVAIRDEVCEN. by an authorized representative of the contractor or laboratory, as applicable. manufacture shall not be construed as a guarantee of the acceptance of the finished product. following: S
47、uch reports shall be signed Acceptance or approval of material during the course of Acceptance tests shall consist of the (1) Individual Tests (2) Sampling Tests 4.4.1 Individual Tests - Each mounting base submitted for acceptance shall be subjected to the individual tests. These tests shall be adeq
48、uate to determine compliance with the requirements of material, workmanship, operational adequacy and reliability. As a minimum, each mounting base accepted shall have passed the following tests: (1) Examination of Product 4.4.1.1 Examination of Product - Mounting bases shall be inspected to verify
49、that the materials, design, construction, physical dimensions, identification marking, and workmanship are in accordance with this specification. (See 3.2 and 3.3). 4.4.2 Sampling Tests - Mounting bases selected for sampling tests shall first have passed the individual tests. Mounting bases shall be selected or sampling tests by the government inspector in accordance with the following unless otherwise specified in the contract or orders: Quantity of Equi
