Disadvantages of metal connectors in- 

 clude: The need for additional individual con- 

 tact seals which are inherent in the inte- 

 grally molded rubber type connector; danger 

 that sealing surfaces may be damaged, caus- 

 ing possible seal failure; susceptibility to cor- 

 rosion, depending on material choice, envi- 

 ronment and the influence of other interfac- 

 ing metals and/or stray electrical currents; 

 need for insulation to provide electrical isola- 

 tion of the conductors; and the need to se- 

 cure and seal these parts. Additionally, ap- 

 plications that require the metal connector 

 to be subjected to a considerable degree of 

 pressure cycling call for special attention to 

 the manner of wiring and how the conduc- 

 tors are supported in the back end of the 

 plug between the cable-end seal and the con- 

 ductor termination. Otherwise, fatigue fail- 

 ure of the conductor can occur. Where nonre- 

 silient parts interface at plug and receptacle, 

 a minimum volume void is always present 

 because necessary dimensional tolerances 

 preclude interfacial contact at this point. 

 This void can account for some electrical 

 degradation due to condensation of moisture 

 in the contact area. This can be significant 

 depending on application and environmental 

 temperature and humidity ranges. Contact 

 insulation composed of compression glass 

 seals must be adequately protected from 

 welding temperatures when components are 

 fastened or sealed by this method. 

 Molded Plastic Connector: 



The molded thermosetting resin type of 

 connector construction is relatively inexpen- 

 sive and ideally suited to volume production. 

 It has many of the same advantages as the 

 all rubber type. For example: It takes fewer 

 components; integral molding requires no in- 

 ternal seals; no insulators are required as 

 the structural material itself is a good dielec- 

 tric; and the material is not subject to salt 

 water corrosion, since it cannot form a gal- 

 vanic couple with adjacent metal parts. 



However, experience has indicated that 

 plastics have many deficiencies as a connec- 

 tor fabricating material. Any one specific 

 thermoplastic or thermosetting resin mate- 

 rial does not seem to combine the desirable 

 electrical properties with all the required 

 physical and mechanical properties neces- 

 sary for use as a deep submergence connec- 



tor. Some of these properties include a high 

 degree of dimensional stability, high impact 

 strength, low mold shrinkage, low water ab- 

 sorption, high compressive strength and non- 

 flammability. 



Fabricating requirements further limit the 

 material choice. These include good moldabil- 

 ity — especially with any necessary reinforc- 

 ing fiber content — at reasonable tempera- 

 tures and pressures. Some of the more com- 

 mon defects found in molded connector parts 

 include the following: Cracks at points of 

 high stress which are generated in the mold- 

 ing process and proliferate with use; threads 

 that fail under load or are damaged by im- 

 pact; failure in areas that are molded resin 

 rich and lack the necessary fiber content; 

 seal surfaces that do not present the re- 

 quired finish due to excessive flash or poros- 

 ity; and a tendency under higher levels of 

 pressure cycling towards minute fiber dis- 

 placement, followed by fatigue and eventual 

 structural failure. 



Though the molded plastic connector has 

 exhibited serious design deficiencies to date, 

 especially for higher pressure applications, it 

 is quite possible that the proper combination 

 of material and design would produce a satis- 

 factory connector for low pressure applica- 

 tions. 

 Molded Elastomer Connector: 



The molded or cast elastomer type of con- 

 nector construction provides the least expen- 

 sive type of underwater connector. Basically, 

 this type of connector consists of a length of 

 cable whose conductors are terminated with 

 male or female plugs. The entire terminal 

 area is molded or cast integral with the cable 

 jacket. The contacts are positioned by exter- 

 nal means until curing or vulcanizing is com- 

 plete. The geometry of the molded area is 

 such as to provide a sealing interface be- 

 tween plug and receptacle and to provide for 

 strain transition between contact area and 

 cable. Because of the resilient qualities of 

 the material used, relatively thick sections 

 are required to provide adequate polariza- 

 tion between plug and receptacle. This re- 

 sults in a large connector. For this reason, 

 polarization, where present in this design, is 

 normally accomplished by contact pattern or 

 by the use of two or more different contact 

 diameters. Neither method is adequate be- 



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