ELECTRO FORMED CONDUCTOR FOR TELEPHONE DROP WIRE 1117 



Fig. 6 — Turning section of the machine where the twenty-five channels of 

 wire, after having been cleaned and partially plated in the tanks on the left, 

 reverse their direction and travel the full length of the building, receiving added 

 copper coating in the series of plating cells. 



The production plating machine has 58 plating cells alternating with 

 57 copper contact rolls. The plating solution is very corrosive so that all 

 surfaces of containers are covered with Koroseal. Copper plates in the 

 bottoms of the cells distribute current to a bed of copper shot which 

 forms the active anode surface. 



A relatively large number of cells is required because of the magni- 

 tudes of the total plating currents involved. Faraday's Law shows that 

 several thousand amperes are required to deposit copper at the rate of 

 0.001" per minute. 



Instantaneous fusion of a steel wire 0.033" in diameter would result 

 if this current were forced through it at one time. The repeated passage 

 of smaller currents which will not overheat the wire will, however, de- 

 posit the same amount of copper. The design of a plating section thus 

 takes the form of a number of plating cells separated by contact rolls. 



The contact rolls are designed to have a wall thickness of copper ade- 

 quate to prevent more than a negligible voltage drop between the two 

 outside wires in the machine. This insures that the same voltage is ap- 



