1、I I MIL-1-49466 2 April 1990 MILITARY SPECIFICATION INSULATOR; DISKS, PLATES, AND WASHERS GENERAL SPECIFICATION FOR This specification is approved fop use by all Departments and Agencies of the Department of Defense. 1. SCOPE 2. APPLICABLE DOCUMENTS 2.1 Government documents. 2.1.1 Specifications, st
2、andards, and handbooks. The following specifications, standards, and handbooks form a part of this specification to the extent specified herein. Unless otherwise specified, the issues of these documents shall be those listed in the issue of the Department of Defense Index of Specifications and Stand
3、ards (DODISS) and supplement thereto, cited in the solicitation. SPECIFICATIONS FEDERAL QQ-S-781 - Strapping, Steel, and Seals. PPP-B-566 - Boxes, Folding, Paperboard. PPP-8-601 - Boxes, Wood , Cleated-Plywood. PPP-B-62 1 - Boxes, Wood, Nailed and Lock-Corner. PPP-B-636 - Boxes, Shipping, Fiberboard
4、. PPP-B-676 - Boxes, Setup. Beneficial comments (recommendations, additions, deletions) and any pertinent data which may be of use in improving this document should be addressed to; US Army Laboratory Command, Reliability, Logistics and Standardization Div., ATTN: SLCET-R-S, Fort Monmouth, NJ 07703-
5、5000, by using the self-addressed Standardization Document Improvement Proposal (DD Form 1426) appearing at the end of this document or by letter. Copyright Communications - Electronics Command Provided by IHS under license with CRAINot for ResaleNo reproduction or networking permitted without licen
6、se from IHS-,-,-vIL-I-474bb 57 m 9979906 0437 1 a “ MIL-1-49466 MI L I TARY MIL-P- 116 - Preservation, Methods of. STANDARDS MI L I TARY MIL-STD-129 - Marking for Shipment and Storage. MIL-STD-794 - Parts and Equipment, Procedures for Packaging of. MIL-STD-1285 - Marking of Electrical and Electronic
7、 Parts. (Copies of specifications, stan.dards, handbooks, drawings, and publications and other Government documents required by contractors in connection with specific acquisition functions should be obtained from the contracting activity or as directed by the contracting activity.) 2.2 Other public
8、ations. The following documents form a part of this specification to the extent specified herein. Unless otherwise specified, the issues of documents not listed in the DODISS shall be the issue of the nongovernment documents which is current on the date of the solicitation. AMERICAN SOCIETY FOR TEST
9、ING AND MATERIALS (ASTM) ASTM E 1225 - Thermal Conductivity of Solids by Means of the Guarded- Comparative-Longitudinal Heat Flow Technique (Application for copies should be addressed to the American Society for Testing and Materials, 1916 Race Street, Philadelphia, PA 19103.) 2.3 Order of precedenc
10、e. In event of a conflict between the text of this specification and the references cited herein (except for associated detail specifications, specification sheets or MS standards), the text of this specification shall take precedence. Nothing in this specification, however, shall supersede applicab
11、le laws and regulations unless a specific exemption has been obtained. 3. REQUIREMENTS 3.1 Specification sheets. The individual item requirements shall be as specified herein and in accordance with the applicable specification sheets. In the event of any conflict between requirements of this specifi
12、cation and the specification sheet, the latter irhall govern. (If a specific requirement specified herein is not required for,an item it shall be indicated on the specification sheet; for example, Thermal impedance - N/A). 3.2 Quality conformance inspection. Insulators shall be products which have b
13、een inspected and passed the quality conformance inspection. 3.3 Material. Insulators shall be fabricated from material as specified. on the applicable specification sheet (See 3.1). 2 Copyright Communications - Electronics Command Provided by IHS under license with CRAINot for ResaleNo reproduction
14、 or networking permitted without license from IHS-,-,-MIL-1-49466 3.4 Design, construction, and dimensions. Design, construction, and dimensions O of the insulators shall be as specified herein and on the applicable specification sheet (see 3.11 3.4.1 Color. Unless otherwise specified, the color of
15、the insulators is optional. Color of insulators shall not affect the part number. 3.5 Thermal impedance. When tested as specified in 4.6 the thermal impedance of the material used to fabricate the insulators shall be no more than the maximum value specified on the applicable specification sheet (see
16、 3.11. 3.6 Marking. The insulators need not be marked. Marking shall be in accordance with 5.3. 3.7 Workmanship. Insulators shall be processed in such a manner as to be uniform in quality and shall be free from surface flaws and other defects that will affect life or serviceability. 4:QUALITY ASSURA
17、NCE PROVISIONS 4.1 Responsibility for inspection. Unless otherwise specified in the contract or purchase order, the contractor is responsible for the performance of all inspection requirements (examinations and tests) as specified herein. Except as otherwise specified in the contract or purchase ord
18、er,the contractor may use his own or any other facilities suitable for the performance of the inspection requirements specified herein, unless disapproved by the Government. The Government reserves the right to perform any of the inspections set forth in the specification where such inspections are
19、deemed necessary to assure supplies and services conform 0 to prescribed requirements. 4.1.1 Responsibility for compliance. All items must meet all requirements of section 3 and 5. The inspection set forth in this specification shall become a part of the contractors overall inspection system or qual
20、ity program. The absence of any inspection requirements in the specification shall not relieve the contractor of the responsibility of ensuring that all products or supplies submitted to the Government for acceptance comply with all requirements of the contract. Sampling inspection, as part of manuf
21、acturing operations, is an acceptable practice to ascertain conformance to requirements, however, this does not authorize submission of known defective material, either indicated or actual, nor does it commit the Government to accept defective material. 4.2 Classification of inspections. The inspect
22、ion requirements specified herein are classified as follows: a. Materials inspection (see 4.3). b. Quality conformance inspection (see 4.4). c. Packaging inspection (see 4.7). 4.3 paterials inspection. Materials inspection shall consist of certification 3 Copyright Communications - Electronics Comma
23、nd Provided by IHS under license with CRAINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-I MIL-1-47466 59 m 9999906 04LbL4L T m MIL-1-49466 supported by verifying data that the materials used in fabrication the insulators, are in accordance with the applicable ref
24、erenced specifications (see 3.11, and when specified the requirements of 3.5, prior to such fabrication. 4.4 Quality conformance inspection. Quality conformance inspection shall include the examination of 4.5. Additionally when 3.5 is a requirement the test of 4.6 shall apply. 4.5 Product examinatio
25、n. Insulators shall be visually and dimensionally examined to verify that design, construction, physical dimensions, marking, and workmanship are in accordance with the applicable requirements (see 3.1, 3.4, 3.6, and 3.7). 4.6 Thermal impedance. Thermal impedance shall be determined by method A (4.6
26、.1) or method B (4.6.2). 4.6.1 Method A. 44.1.1 Apparatus. The general features of the apparatus are shown in figure 1. All contacting surfaces shall be smoothly finished to within 16 microinches (0.4 micrometers) so as to approximate a true plane for the meter bars in contact with the specimen surf
27、ace. A List of the basic components required for determination of thermal impedance is as follows: a. Heater - A block of copper or other highly conductive material, into which wire wound cartridge heaters are inserted. This block is thermally insulated by a 5 mm layer of epoxy FR-4 or similar mater
28、ial. Outside this layer is a guard heater of similar-construction to thermally insulate the heater from the press and ensure that all heat is transferred to the upper meter bar. b. Meter bars - Two meter bars constructed from high thermal conductivity material having parallel working surfaces and go
29、od surface finish. A suitable material of construction is a high puri-ty grade aluminum. c. Reference calorimeter - A reference calorimeter constructed from a material which has a well characterized thermal conductivity over the range of test temperatures to be used. A recommended material is SRM-14
30、62 austenitic stainless steel. A list of other useful materials of construction is in ASTM E 1225. d. Cooling unit - The cooling unit is a metal block cooled by fluid supplied from a constant temperature bath such that the temperature is maintained uniform at 2 0.2 *C. e. Press - A press capable of
31、transmitting the specified force to the test fixture through a free-floating spherical seat attachment, preventing offset loads and uneven pressures on the test specimen. f. Insulation - A fibrous thermal insulating blanket. 4 Copyright Communications - Electronics Command Provided by IHS under lice
32、nse with CRAINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-1-49466 4.6.1.2.1 Specimens. Two pieces of material of the thickness specified in 3.1 and of the same area (length and width) as the meter bars shall be prepared from specimen. The specimen shall be t
33、ested in the as-received state. Any obvious contamination shall be removed by a suitable, non-reactive solvent prior to testing. Any cleaning shall be followed by drying procedures to assure the removal of all solvents. 0 the insulator .material specified in 3.3. The pair shall be designated as the
34、test 4.6.1.2.2 Apparatus setup. The general arrangement of the components are illustrated in figure 1. Center the test specimen between the two meter bars and insert the reference calorimeter between the lower meter bar and the cooling unit. Place the assembled test stack into the press. Apply therm
35、al insulation around the stack if measurements are to be made at temperatures above 27 OC. With the press, apply a force of 300 psi (2.07 Wal of pressure to the stack. Circulate cooling fluid and apply power to the heating element. Maintain the temperature of the guard heater to within i 0.2 OC of t
36、he heater. Continuously adjust the applied force in the press during heat-up to counter act the increased pressure on the specimen due to thermal expansion. 4.6.1.2.3 Measurement. Record the temperatures of the meter bars and the reference calorimeter at equilibrium. Equilibrium is attained when 2 s
37、uccessive sets of temperature readings are taken at 15 minute intervals and the differences between the two are observed to be within L 0.2 OC. 4.6.1.3 Calculations. a 4.6.1.3.1 Calculate heat flow from the reference calorimeter as follows: As A X Q where : - - kl - TF Q = heat flow in watts h6 = th
38、ermal conductivity of reference calorimeter, W/in OC A = area of the reference calorimeter, square in. TE = upper temperature of calorimeter, OC TF = lower temperature of calorimeter, OC X = distance between the reference calorimeter thermocouples, inches 4.6.1.3.2 Calculate the temperature of the u
39、pper meter bar as follows: where : T1 = temperature of the upper meter bar, OC TA = upper temperature of the upper meter bar, OC TB = lower temperature of the upper meter bar, OC dr = distance between thermocouples of upper meter bar, inches 5 Copyright Communications - Electronics Command Provided
40、by IHS under license with CRAINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-I-474bb 57 m 77777Ob OLIlbL43 3 MIL-1-49466 dm = distance from the lower thermocouple to the lower surface of the upper meter bar, inches 4.6.1.3.3 Calculate the temperature of the lo
41、wer meter bar as follows:- T4 = Tc + $lc-T) where : T4 = temperature of the lower meter bar, OC TC = upper temperature of the lower meter bar, OC TD = lower temperature of the lower meter bar, OC de = distance from the upper thermocouple to the upper surface of the lower do = distance between thermo
42、couples of lower meter bar meter bar , inches 4 .S. 1.3.4 Calculate thermal impedance as follows : 6 = (Tr-Ta)/q where : 8 = thermal impedance, OC in“/W q = rate of heat flow through the sample per unit area, Q/A 4.6.2 Method B, 4.6.2.1 Apparatus, List of basic components required for determination
43、of thermal impedance is as follows: a. Heater/sensor - an electrically insulated wire-wound coil for applying a measured quantity of heat energy into the assembly and a second winding used to sense the temperature in the assembly. It shall have parallel strands of #40 AWG copper wire having identica
44、l thermal resistance at 20 OC. The surface areas are closely matched. Details are illustrated in Fig 4. b. Wheatstone bridge - is used for minimizing zero shifts caused by small increments in the temperature of the heat sinks. The bridge, illustrated in F.ig. 3, uses an amplifier with a gain of 2000
45、X. The bridge shall have a standardization resistor specific to the temperature coefficient of resistance of the heater/sensor strand wire. c. Press - a spring loaded, screwthread, or hydraulic arbor press is used to maintain essentially constant force with changes in operating temperatures. d. Shee
46、t, thermally conductive - A thin, very resilient and flexible sheet material to cover the two sensors and minimize the strain sensitivity of the heater/sensors. A .1 inch (25 micrometer) polyester film is satisfactory for this material. 6 Copyright Communications - Electronics Command Provided by IH
47、S under license with CRAINot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-1-49466 4.6.2.2 Procedure. 4.6.2.2.1 Specimens. Six pieces of material of the thickness specified in 3.1 hawing ag area greater than the heater/sensor shall be prepared from the insulator
48、material specified in 3.3. The six pieces shall be designated as the test specimen. The specimen shall be tested in the as-received state. Any obvious contamination shall be removed by a suitable, non-reactive solvent prior to testing. Any cleaning shall be followed by drying procedures to assure th
49、e removal of all solvents. 4.6.2.2.2 Apparatus setuv. The general assembly of the appapatus is shown in figure 2. A schematic electrical layout is shown in figure 4. Place specimens in the assembly in accordance with configuration 1 of figure 2. With the press apply a force of 300 psi (2.07 MPa) to the system. Leave the specimen under this condition for a minimum of one hour. 4.6.2.2.3 Measurement. Turn on and zero the amplifier with the bridge p
