1、7- NIL-S-253ZB 73 777770b OLL7155 MIL-S-25392 B(ASG) 8 MAY 1968 Superse 20 December 1963 MTLITARY SPECIl?ICATJ;G2; SANDWICH CONSTRUCTION, PLASTIC RESIN, GLASS FABRIC BASE, LAMINATED FACINGS AND URETHANE FOAMED-IN-PLACE CORE, FOR STRUCTURAL APPUCATIONS This specification has been approved by the Depa
2、rtment of the Air Force and by the Naval Air Systems Command. 1. SCOPE 1.1 Scope. - This specification covers plastic molded sandwich construction using glass fabric base plastic laminate facings and urethane foamed-in-place core material for aircraft structural applications up to 350“ F, including
3、ali aircraft external plastic parts, and other weapons appications, 1.2 Classification. - The molded sandwich construction, foamed-in-place core material shall be of the following types and classes, as specified (see 6.2): TYP 1 vpe II Class 1 Class 2 General purpose (nonelectrical) General purpose
4、- for exposure to 165“ F Heat resistant - for exposure to 350“ F Radar purpose (electrical) (see 3,5) 2. APPLICABLE DOCUME3TS 2.1 The following documents, of the issue in effect on date of invitation for bids or request for proposal, form a part of this specification to the extent specified herein:
5、SPECIFICATIONS Federal L-P-383 Plastic Material, Polyester Resin, Glass Fiber Base, Low Pressure Laminated Militarq MIL-R-7575 MIL-C-8087 MIL-C-9084 MIL-R-9300 Resin, Polyester, Low-Pressure Laminating Core Material, Foamed-in-Place, Urethane Type Cloth, Glass, Finished, for Polyester Resin Laminate
6、s Resin, Epoxy, Low Pressure Laminating FSC 9339 1 -7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MILS-25392B( ASG) Plastic Laminate Materials and Sandwich Construction, Glass Fiber Base, Low Pressure Aircraft Structural, Process Specification Re
7、quirements Pressure Lanrinating MIL-P-94.00 MIL-R-2504.2 Resin, Poyester, High Temperatwe Resistant, Low STANMRDS, Federal. FEDO TEST METHOD Plastics: Methods of Testing STD. No. 4.06 Hlitary MIL-STD-l.43 MILSTb401 Specifications and Standards, Order of Precedence Sandwich Construction and Core Mate
8、rials, for the Selection of General Test Methods (Copkes of specifications, standards, drawings, and publications required by suppliers in connection with specific procurement functions should be obtained from the procuring activity or as directed by the contracting officer,) 3. RE;QUIREMENTS 3.1 Pr
9、eproduction. - This specification provides for preproduction inspection. 3.2 Materials. - Materials other than those specified may be used, provided they are suitable for the purpose. materials shall be selected in accordancB with MICSTD-243. Specifications governing these 3.2.1 Sandwich constructio
10、n, - The sandwich construction shall consist of foamed-in-place core material bonded to faces of glass fabric base laminated plastic material. 3.2.2 Face material. - The face material shall conform to the workmanship requirements of the applicable plastic materials specifications for each type and c
11、lass of sandwich construction. 3,2,2.1 Glass fabric. -The glass fabric shall conform to MIL-C-9084. 3.2.2.2 ,Laminating resins. - For type I appiications, the lamhating resin shall conform to MIL-R-7575 or MIER-9300. For type II applications, the laminating resin shall conform to ML-R-9300 or MILR-2
12、5042, type I and type II applications, the laminating resin shall also meet the additional electrical requirements of the aDplicable specification for the laminating resin, type and class requirements of MILC-8087 fQr the particular type and Glass sandwich structure fabricated. For class 1, 3.2.3 Co
13、re material, - The core material shall conform to the corresponalng 2 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-NIJ,-s-25392U( ASG ) 3.2,4 BondinR. - The foamed-in-place core material shall be capable of bonding to the premlded plastic resin, g
14、lass fabric base low pressure laminated skns. The surface of the skin to be in contact with the foam shall be properly prepared to remove surface gloss and parting agents. applied to the inner surface of the laminated skins before foaming to obtain a good bond. For class 1 materials, any adhesive pr
15、imer used shall not impair the electrical properties specified in 3.5. shall not exceed the maximum allowable requirements of figure 1 for the test panel of dimensions described in 4.3*1* 3.3 Process. - A detailed description of the manufa3turing and fabricating process and methods of control of man
16、ufacturing variables shall be submitted by the contractor in the form of a titled, numbered, and dated process specifica- tion, together with the nwaber of panels specified in 4.3.1, and 4,3.2 (the process specification shabl contain the results of al1 physical and mechanical tests required under pr
17、eproduction testing) to the procuring activity for approval in conformance to MTL-P-9400 and this specification, After approval, the process specification shall form a part of this specification, and copies shall be made available by the contractor for use by authoried Government inspectors at the c
18、ontractors plant. of the test specimens cut from sandwich panels fabricated as described in 4.4.1 shall be determined on the minimum and maximum sandwich weight (on a lb/cu.ft . basis, figure 1) that the manufacturer anticipatbs producing. in sandwich form, the mechanical strength prpperties of type
19、 I and type II materials shall conform to the requirements of figures 2 and 3, respectively. 3*4.2 Mechanic.al strength properties at 165O F. - The flexural, flatwise compression, and flatwise tensile strengths of the plastic sandwich,when tested at 165O F, shall be not less than 70 percent of the r
20、oom temperature requirements as given in figure 1 for type I materials. flatwise compression, and flatwise tensile strengths for type II sandwich, when tested at 350 F, shall be not less than 75 percent of the room temperature requirements as given in figure 3. Pwer trmsssion efficiency of foam sand
21、wich panels, when tested at a frequency between 8.5 to 10 kilomegacycles (designed for optimum performance at 9,375 il0 megacycles) and oriented at a 20-degree angle of incidence for both parallel and perpendicular polarization, shall be at least 95 percent in the Itas receivedtt condition and at le
22、ast 90 percent after environmental conditioning (4,5.4) and testing in accordance with 4.6*7+. material. An adhesive primer my be 3*2,5 Sandwich weight. - The sandwich weight for given core densities 3.4 Mechanical strength properties, - The mechanical strength properties 3.4.1 Mechanical strength p
23、roperties at room temperature. - When tested 3.4.3 Mechanical strength properties at 350“ F. - The flexural strength, 3.5 Electrical properties for types I and II (see figure 4). - The electrical No electrical tests are required for class 2 3 .- I Provided by IHSNot for ResaleNo reproduction or netw
24、orking permitted without license from IHS-,-,-1.40 l. 32 1.24 1.16 1.08 1.00 1.92 84 .i% .68 60 4 BIMJRE 1. Maximum sandwich weight of foam panel versus core density Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-25392B 93 9999906 0339359 3 I
25、I “X Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-253928 93 9999906 Oll9160 M U I 4 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-253928 73 m 7997906 OLLSLbL T mi ML-S-25392B ( ASG )
26、-3 -5 7 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-253728 73 m 7779906 OLL9L62 L m MICS-253c);)I3( WG) 3.6 Dimensions and weight. - The face thickness, overall sandwich con- struction thickness,-and maximum weight in pohds per square foot,
27、 shall be as specified in the specifications, .drawings, or contracts for the molded sand- wich construction parts. 3,7 Workmanship. - 3.7.1 Cured foam core. - Workmanship requirements of WLC-8087 shall 3.7.2 Defects. - The minimum requirements for the sandwich and maximum apply ta the cured foamed-
28、in-place core material used in sandwich construction. allowable and reparable defects shall be compleely described in the mnuiac- turer 1s process specification. the maximum allowable defects in nature, size, or extent beyond skbisfactory reparable condition shall be rejected. In general, the workma
29、nship and quality of the plastic sandwich part shall conform to MIL-P-9400 and this specification, Blistering. - The finished sandwich part shall show no blistering under service or service simulated conditions. skin of the finished part or other methods of inducing porosity on the inner skin to ins
30、ure against blistering under service or service simulated conditions is prohibited, 3,s Dimensions and makeup of sandwich construction. - The thickness, dimensions, and makeup of the laminates and core material, comprising the number of plies of the various fabrics, their position and direction, typ
31、e of resin and other specific information for the sandwich construction shall be specified in drawings, specifications,or contracts for the parts. Overlays, - Glass fabric base low pressure laminated plastic material shall not be made with a gel resin overlay, integrally molded or otherwise, or with
32、 any other such thick resin surface, or any other surfacing material, unless such overlay or surfacing is specifically approved by the procuring activity. 4. QUALITY ASSURANCE PROVISIONS Any sandwiches having defects which exceed 3.7.3 Drilling of holes on the inner 3.9 4.1 Responsibility for inspec
33、tion. - Unless otherwise specified in the contract or purchase order, the supplier is responsible for the performance of all inspection requirements as specified herein, specified in the contract or order, the supplier may use his own or any other facilities suitable for the performance of the inspe
34、ction requirements specified herein, unless disapproved by the Government. reserves the right to perform any of the inspections set forth in the specifi- cation where such inspections are deemed necessary to assure supplies and services conform to prescribed requirements, Ekcept as otherwise The Gov
35、ernment 8 Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-S-25372B 73 M 7777906 OLL7163 3 EfIGS-25392B( ASG) - ! I. 4.2 Classification of inspections, - The inspection of the sandwich . construction shall be classified as follows: (a) Preproducti
36、on inspection (4.3) (b) Quality conformance inspection (4.4) 4.3 Preproduction inspection. - 4.3.1 Preproduction sample, - Prior to production of parts on contract, a sample flat sheet of sandwich construction shall be made up in accordance with the approved process specification of each of the type
37、s and classes of core materials to be employed in production parts and shall be tested for the appicable properties specified in figures 2 and 3. In the event that parts having different core dennitdes are produced, two panels each of the minimum and-maximum core density used shall be submitted. ove
38、rall thickness shall be foamed in a vertical direction between MILC-9084, type VIX1 glass-fabric base parallel laminated skina ,0.030 -.O03 inch thick, conforming to the workmanship requirements of L-P-383,-, The test panel shall be marked to show the direction of foaming. The method used for mixing
39、 the components, as well as for pouring and curing, shall be in accordance with the manufacturer 1s instruction sheet. tested to determine conformance with the applicable requirements specified herein. These tests need be made only once and need not be repeated for new orders or different parts prov
40、ided that the materials and processes have not been changed, and that a certified statement to this effect is furnished the inspector with a copy of the report of the tests made, cases where the Government inspector considers it necessary in order to obtain material meeting the requirements of this
41、specification, he shall have the right to require the performance of any of the tests at any time. one sheet may be made and used for the tests provided that they are all comparable as to material and process of fabrication. Flat panels l/;?-inch Specimens from these panels shall be However, in thos
42、e More than 4.3.2 Electrical tests - class L materials., - Electrical tests on class 1 materials shall be perfarhed by the procuring service on two foam sandwich panels, one each of the minimum denaity core material to be produced by the manufacturer. size, with the same construction specified in 4.
43、3.1, except that the thickness shall be determined by the manufacturer on the basis of electrical design characteristics in order to conform to the requirements specified in 3.5. The outside edge of the panels shall have a 1-inch wide solid laminate border of the same type laminate used for the skin
44、 (see 6.4). fabrication process (3.3) of the panels shall be the same as those for the panels tested for mechanical strength properties (3.4). The foam sandwich panels shall be 2 feet by 3 feet in overall The core densities and 9 Provided by IHSNot for ResaleNo reproduction or networking permitted w
45、ithout license from IHS-,-,-MIL-S-25372B 73 W 7777706 OLL7Lb4 5 W MIL-S-25392B( ASG ) -, 4.4 Quality conformance inspection, - Quality conformance inspection shall consist of the following: (a) Visua examination (4*6*1) (b) Weight (4.62) (c) Compression flatwise (46.3) 4.4.1 Sampling, - Unless other
46、wise specified by the procuring activity, from each lot of foamed-in-place core material and glass fabric laminate to be used in the fabrication of parts, at least one sample flat panel of sand- wich construction plastic material shall be made up in accordance with the approved process specification
47、 of each of the types of care materials to be employed in production. This panel shall be tested for flatwise compressive strength at room temperature, and 165O F for type I and 350“ F for type II in accordance with 4.6.3, 4.6.4, and under test conditions of 4.5. The overall requirements (density, e
48、tc.) shall conform to figures 2 and 3. Five specimens shall be tested for each test from each sample. 4.4.2 the 30-mnute exposure, the The flexure specimens shall be tested at room temperature Unmedi- LO Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-
49、,-MIL-S-25392B 93 = 999990b OLL9L65 7 m 4.5.4 Environmental conditioning for electrical test ranelse- Either a thermometer or thermocouple shall be inserted into the approximate centerline of the specimen. The specimen shall be heated or cooled to temperature equilibrium, 750 C (1650 F) and -540 C (-6.50 F), respectively. The specime
