1、 INCH-POUND MIL-DTL-55668D February 20, 2009 SUPERSEDING MIL-DTL-55668C 9 September 2005 DETAIL SPECIFICATION CORD, ELECTRICAL; AUDIO, SUBMINIATURE (RETRACTILE AND STRAIGHT) Reactivated after 10 September 1993 and may be used for new and existing designs and acquisitions This specification is approv
2、ed for use by all Departments and Agencies of the Department of Defense 1. SCOPE 1.1 Scope. This specification covers subminiature audio helical retractile cords and straight cords with either stranded wire or tinsel wire conductors, for accessories associated in for the use with microphone, telepho
3、ne, switchboard, and associated communication equipment. These cords are intended for operations at audio frequencies and temperatures from -55 C to +85 C with a high degree of flexibility. Each retractile cord is designed for extension in normal service up to 6 times its nominal retracted helical l
4、ength. 1.2 Classification. The types of cords covered by this specification are classified as follows: Type I - Retractile cords with stranded wire conductors. Type II - Retractile cords with tinsel wire conductors. Type III - Straight cords with stranded wire conductors. Type IV - Straight cords wi
5、th tinsel wire conductors. 2. APPLICABLE DOCUMENTS 2.1 General. The documents listed in this section are cited in sections 3, 4 or 5 of this specification. These lists do not include documents cited in other sections of this specification or recommended for additional information or as examples. Whi
6、le every effort has been made to ensure the completeness of these lists, document users are cautioned that they must meet the requirements specified in the documents cited in sections 3, 4 or 5 of this specification, whether or not they are listed. 2.2 Government documents. 2.2.1 Specifications, sta
7、ndards and handbooks. The following specifications, standards and handbooks form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. FEDERAL STANDARD 2/18/20092/18/20091 1Beneficial comment
8、s, recommendations, addtions, deletions, clarifications, etc., and any data that may improve this document should be sent to: Defense Supply Center, Columbus, ATTN: DSCC-VAI, P.O. Box 3990, Columbus, Ohio 43218-3990, or email to WireCabledscc.dla.mil. Since contact information can change you may wan
9、t to verify the currency of this address informaiton using the ASSIST Online database at http:/assist.daps.dla.mil. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-55668D 2 FEDERAL STANDARD FED-STD-228 - Cable and Wire, Insulated; Methods of
10、Testing. DEPARTMENT OF DEFENSE SPECIFICATIONS MIL-C-572 - Cords, Yarns, and Monofilaments, Organic Synthetic Fiber. MIL-I-631 - Insulation, Electrical, Synthetic Resin Composition Non-Rigid. DEPARTMENT OF DEFENSE STANDARDS MIL-STD-104 - Limits for Electrical Insulation Color. MIL-STD-202 - Test Meth
11、ods for Electronic and Electrical Component Parts. (Copies of these documents are available online at http:/assist.daps.dla.mil/quicksearch/ or from the Standardization Document Order 700 Robbins Avenue, Building 4D, Philadelphia, PA 19111-5094.) 2.3 Non-Government publications. The following docume
12、nts form a part of this document to the extent specified herein. Unless otherwise specified, the issues of these documents are those cited in the solicitation or contract. ASTM INTERNATIONAL ASTM D1248 - Standard Specification for Polyethylene Plastics Molding and Extrusion Materials. ASTM D4101 - S
13、tandard Specification for Propylene Plastic Injection and Extrusion Materials. ASTM B33 - Standard Specification for Tinned Soft or Annealed Copper Wire for Electrical Purposes. (Copies of these documents are available online from http:/www.astm.org or ASTM International, P.O. Box C700, 100 Barr Har
14、bor, West Conshohocken, PA 19428-2959.) Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-55668D 3 NATIONAL CONFERENCE STANDARDS LABORATORIES (NCSL) NCSL Z540.3 - General Requirements for Calibration of Measuring and Test Equipment (Copies of t
15、his document are available from http:/www.ncsli.org or from the National Conference of Standards Laboratories (NCSL), 2995 Wilderness Place, Suite 107, Boulder, CO 80301-5404.) INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO) ISO 10012-1 - Quality Assurance Requirements for Measurement Equipment
16、 / Metrological Confirmation System for Measuring Equipment. (Copies of these documents are available online at http:/www.iso.ch or from the International Organization for Standardization American National Standards Institute, 11 West 42ndStreet, 13thFloor, New York, NY 10036.) 2.4 Order of preceden
17、ce. Unless otherwise noted herein or in the contract, in the event of a conflict between the text of this document and the references cited herein, the text of this document takes precedence. Nothing in this document, however, supersedes applicable laws and regulations unless a specific exemption ha
18、s been obtained. 3. REQUIREMENTS 3.1 First article. The cords furnished under this specification shall be products which have been tested to and have passed the first article inspection. First article approval is valid only on the contract under which it is granted, unless extended by the government
19、 to another contract (see 6.4). 3.2 Conductors. 3.2.1 Stranded wire. Each stranded wire shall be the equivalent of No. 26 American Wire Gauge (AWG) and shall consist of 26 strands of No. 40 AWG wire having a cross-sectional area of 9.9 circular mils and stranded with a .25 inch (6.35 mm) nominal, .3
20、8 inch (9.65 mm) maximum, unidirectional left-hand lay. The diameter of the stranded conductor shall be approximately .019 inch (.483 mm). Each strand shall be tinned, soft or drawn and annealed cadmium-copper alloy having a 1 percent, nominal, cadmium content and a minimum conductivity of 85 percen
21、t. 3.2.1.1 Tin-coating. Each strand shall be tin-coated with commercially pure tin. The tin-coating, continuity, adherence, and finish shall meet the requirements of ASTM B33 (see 4.7.2.1). 3.2.1.2 Stranded wire tensile strength and elongation. When tested as specified in 4.7.2.2, the tensile streng
22、th and elongation of the coated strands, removed from the wires of insulated conductors prior to cabling, shall be as follows: Tensile strength Elongation in 10 inches (254 mm) 40,000 psi (min.) 13 percent (min.) 3.2.1.3 Stranded wire resistance. Each strand shall have a direct current (dc) resistan
23、ce of not more than 1.27 ohms per foot. The dc resistance of the No. 26 stranded conductor shall be not more than .0556 ohms per foot. Resistance values should be measured at or corrected to 20 C when tested in accordance with 4.7.2.3 (see 6.3). Provided by IHSNot for ResaleNo reproduction or networ
24、king permitted without license from IHS-,-,-MIL-DTL-55668D 4 3.2.2 Tinsel wire. Tinsel wire shall meet the requirements type IV tinsel electrical wire, having an overall dimension of 0.022 inch (.56 mm) 0.002 inch (.05 mm) and a breaking load minimum of 10 pounds (see 6.3). 3.3 Insulation. The insul
25、ation for both stranded and tinsel wire conductors shall be a crystalline ethylene-propylene copolymer thermoplastic meeting the requirements of ASTM D4101. Insulation removed from insulated conductors of finished cords shall meet the requirements of ASTM D1248 with the following exceptions: a. Cold
26、 bend shall be performed at -55 C. b. For insulation removed from tinsel conductors, the ultimate elongation shall be 250% minimum, and the tensile strength shall be 2,500 PSI minimum. When tested for heat shock; there shall be no evidence of cracking. 3.3.1 Insulation wall thickness. Wall thickness
27、 at any section of insulation shall be nominal .007 inch (.178 mm); minimum .004 inch (.102 mm). 3.3.2 Dimensions of insulated conductors. The diameter of the insulated stranded and tinsel conductors shall be .035 inch (.889 mm), +.004, -.002 inch (+.102 mm, -.051 mm). 3.3.3 Insulation colors. Color
28、 of insulation shall conform to MIL-STD-104, class 1. The colors of individual insulated conductors in a core complement shall be in the following sequence: 1. Black 6. Yellow 2. White 7. Blue 3. Red 8. Purple 4. Green 9. Brown 5. Orange 10. Gray 3.4 Fibers and yarns. All synthetic yarns and fibers
29、employed as servings, binders, fillers, cores for tinsel strands and wires, and staycords shall be as specified herein. 3.4.1 Fillers. Filler yarn shall be used between insulated conductors to form an essentially circular cross-section core and provide a slippage between the insulated wires. Fillers
30、 shall be a yarn conforming to MIL-C-572 type PSTR (polyester) or type CTA (cellulose triacetate), or a polypropylene yarn or twisted polypropylene film. 3.4.2 Staycord. Staycord shall consist of a polyaryl-amide fiber conforming to MIL-C-572 type PAA. The cord shall have a minimum breaking strength
31、 of 20 pounds for cords of 2, 3, and 4 conductors, and 30 pounds for cords of 5 to 10 conductors. The filaments of the staycord shall be bonded together with a fungus-inert adhesive in order to facilitate knotting during termination of the finished cord. 3.4.2.1 Center core. If necessary to provide
32、a center core larger in diameter than the staycord, a filler material as specified in 3.4.1 shall be served around the staycord. Provided by IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-55668D 5 3.5 Shield. Shielding shall be served tinsel strands. Th
33、e ribbon comprising the strands shall be silver or tin-coated cadmium-copper of .0095 inch (.241 mm) nominal width and .0009 inch (.023 mm) nominal thickness. A strand shall consist of a single ribbon, spiral-wrapped 54 turns per inch, nominal, around a cotton thread, or a polyaryl-amide thread conf
34、orming to MIL-C-572, type PAA. The shield shall consist of 10 tinsel strands laid adjacent to each other, and spiral-wrapped around the insulated conductor in an even, helical, right-hand lay, with a minimum of 60 turns per foot. At no cross-section should there be less than eight strands in a turn.
35、 Shield coverage shall be 80 percent minimum, as calculated in 4.7.5. An overlapping spiral-wrap of .0005 inch (.013 mm) nominal thickness polyester tape in accordance with MIL-I-631, type G, shall be applied in a right-hand lay over the shield. Another tape may be placed between the insulation and
36、the shield. The diameter of the taped, shielded insulated wire shall be approximately .052 inch (1.32 mm). 3.5.1 Shield resistance. The dc resistance of a shield strand prior to application on the insulated conductor shall be 2.50 per foot maximum, measured at, or corrected to, 20 C (see 6.3). 3.6 J
37、acket. The jacket shall be a smooth, dense, uniform black elastomer free of surface irregularities. Jacket dimensions shall be as specified in table . The wall thickness shall be measured on the straight ends. The jacket material shall be a black vulcanized rubber compound based on one of the follow
38、ing: a. Styrene butadiene rubber (SBR) or blend of SBR and polyisoprene rubber, not exceeding 35 percent natural or synthetic polyisoprene by weight. b. A blend of SBR and ethylene-propylene terpolymer (EPDM), with 25 percent EPDM by weight, minimum. c. EPM rubber or EPDM rubber. 3.6.1 Jacket materi
39、al properties. Vulcanized rubber jacket materials shall meet the requirements of jacketing compound, type JS-L low temperature, heat resistant, styrene butadiene rubber, except as specified in table II. The actual values shall be recorded and forwarded with first article sample test data (see 3.1).
40、Unless otherwise indicated, specimens shall be taken from the straight section of finished cord; for first article inspection testing, cords may be made up with extra-long straight sections. 3.6.2 Anti-deterioration agents. The rubber compound shall contain anti-oxidants, anti-ozonants, and sunproof
41、ing waxes of the types and amounts necessary to provide long-term protection, yet not interfere with adhesion to subsequent rubber strain-reliefs, seals, or crotch-splices. 3.7 Cord construction. 3.7.1 Cord construction parameters. The core shall consist of a staycord in the center around which the
42、insulated conductors and fillers are twisted in a right-hand lay. Powdered soapstone (lubricant) shall be applied to the completed core just prior to jacketing the cord. For a retractile cord, the helical portion shall have a left-hand lay with adjacent turns contiguous and a straight length of cord
43、 at each end tangent to the coil. The cord construction parameters consisting of the number of conductors, number of shielded conductors, core diameter, core lay, jacket wall thickness, jacket diameter, and, for retractile cords, the helix outside diameter shall be specified in table I. Provided by
44、IHSNot for ResaleNo reproduction or networking permitted without license from IHS-,-,-MIL-DTL-55668D 6 TABLE I. Construction dimensions (*) for straight and retractile cords. Total number of conductors Number of unshielded conductors Number of shielded conductors Core dia. Nom/(mm) Core lay Nom/(mm)
45、 Core lay Max./(mm) Jacket wall thickness Nom/(mm) Jacket wall thickness Min/(mm) 2 2 0 .083/(2.11) .4735/(11.1) .5625/(14.3) .026/(.66) .016/(.406) 3 3 0 .085/(2.24) .625/(15.9) .75/(19) .040/(1.02) .024/(.024) 3 2 1 .095/(2.41) .4375/(14.3) .5625/(14.3) .035/(.889) .021/(.533) 4 4 0 .090/(2.29) .6
46、25/(15.9) .75/(19) .037/(.94) .022/(.559) 4 3 1 .095/(2.41) .625/(15.9) .75/(19) .035/(.889) .021/(.533) 5 5 0 .102/(2.59) .625/(15.9) .75/(19) .031/(.787) .019/(.483) 5 4 1 .098/(2.49) .625/(15.9) .75/(19) .033/(.838) .020/(.508) 6 5 1 .110(2.79) .625/(15.9) .75/(19) .027/(.686) .016/(.406) 7* 7 0
47、.116/(2.95) .75/(19) .875(22.2) .037/(.94) .022/(.559) 8* 7 1 .125/(3.17) .75/(19) .875(22.2) .032/(.813) .019/(.483) 9* 7 2 .130/(3.30) .75/(19) .875(22.2) .303/(.762) .018(.457) TABLE I. Construction dimensions (*) for straight and retractile cords - Continued. * - All dimensions are in inches Tot
48、al number of conductors Number of unshielded conductors Number of shielded conductors Jacket diameter Nom/(mm) Jacket dia. tolerance /(mm) Helix OD for retractile cords Nom/(mm) Helix OD for retractile cords Max/(mm) 2 2 0 .135/(3.43) .006/(.152) .5000/(12.7) .6250/(15.9) 3 3 0 .165/(4.19) .007/(.178) .5625/(14.3) .71825/(18.2) 3 2 1 .165/(4.19) .007/(.178) .5625/(14.3) .71825/(18.2) 4 4 0 .165/(4.19) .007/(.178) .5625/(14.3) .71825/(18.2) 4 3 1 .165/(4.19) .007/(.178) .5625/(14.3) .71825/(18.2) 5 5 0 .165/(4.19) .007/(.178) .5625/(14.3) .71825/(18.2)
