Development and Manufacture of 



Electroformed Conductor for 



Telephone Drop Wire 



By A. N. GRAY and G. E. MURRAY 



(Manuscript received June 15, 1953) 



Telephone drop wire is that familiar black overhead wire which brings 

 the telephone service to the home. It is a parallel pair of conductors separated 

 and positioned in an extruded insulation, covered by a cotton serving and 

 jacketed with a neoprene compound of tire tread-like qualities. In the past, 

 a cast copper jacketed steel ingot, rolled and drawn to size, has been used 

 to provide a wire that combines high strength and good conductivity. In order 

 to assure more than a single source of supply and to provide improved 

 mechanical and electrical characteristics, a completely new plant has been 

 constructed for continuous plating of steel wire at completed size. This process 

 provides a stronger, yet smaller and, therefore, less costly wire than was 

 possible previously. Plating is done at 100 feet per minute on 25 wires 

 simultaneously. The conductor is then processed as formerly to provide the 

 neoprene jacketed drop wire. 



HISTORICAL BACKGROUND 



It has been customary in manufacture to apply a lead and a brass 

 plate to drop wire conductor to secure good adhesion to the insulating 

 compound. The brass proiddes the adhesion while the lead prevents at- 

 tack on the copper by the sulfur in the rubber. In 1941, two tandem lead 

 and brass plating machines were placed in service at the Point Breeze 

 Works of the Western Electric Company to apply these coatings on a 

 production basis. Their successful operation proved that electrolytic 

 deposition of two metallic coatings in tandem at high speed was com- 

 mercially practicable. It was not difficult to imagine the addition of a 

 copper plating section to deposit copper, in addition to lead and brass, 

 on a steel wire as a combined operation. The technical problems involved, 



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