1100 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1953 



however, were of considerable magnitude, and their successful solution 

 required a substantial amount of investigation and development. 



Such a process appeared to offer a number of attractive features. The 

 maximum strength of the steel core could be utiUzed since no compromise 

 in physical properties would be required to permit rolling and drawing. 

 A highly uniform cross section could be secured which would provide 

 continuous copper protection for the steel core against corrosion. Since 

 the steel core wire would be a standard commercial item available from 

 a number of manufacturers, alternate sources would be available to 

 assure continuity of supply. 



There were also substantial economic inducements. The higher 

 strength wire of uniform construction would reduce the cost of trouble 

 calls to the Bell System. It appeared that a plant could be designed 

 which would require no more labor to operate than was required for the 

 existing lead-brass plating operation. By starting with a steel wire of 

 uniform and circular cross section and applying a uniform copper jacket, 

 the desired physical and electrical requirements could be met by a con- 

 ductor 2- J^ thousandths smaller in diameter, which would, in turn, reduce 

 the overall dimension of the finished product. Although this reduction 

 might appear small, the very large footage of wire required indicated a 

 saving of a half -million pounds of copper a year, and a combined saving 

 of steel, copper, rubber, cotton and neoprene, all strategic materials, of 

 a million pounds a year. Combined savings to the Bell System Operating 

 Companies and Western Electric Company were estimated at better 

 than one million dollars a year. 



World War II prevented further work until 1946 when the project was 

 reopened and methods of obtaining heavy copper deposits investigated 

 on a laboratory scale. Initial developments showed promise and late in 

 the year, a separate development laboratory was set up to investigate 

 various electro-chemical problems and to develop information on which 

 a pilot plant could be designed. The term "Electroforming" was first 

 applied at this time because it was apparent that the process was not to 

 be one of electroplating in the ordinary sense but rather was to substan- 

 tially change the physical and electrical properties of the wire. In other 

 words, the terminology was intended to differentiate between utility 

 and what are usually decorative or protective functions. 



A pilot plant was built and installed which operated successfully the 

 first day it was placed in operation. The results obtained on the pilot 

 machine exceeded expectations. The limiting current density for the acid 

 copper plating solution determined in the laboratory was 1,000 amps./sq. 

 ft., whereas 2,000 amps./sq. ft. was realized on this machine. This in- 



