216 



BELL SYSTEM TECHNICAL JOURNAL 



oxide, which caused the metal to shrink in solidifying.*' When ex- 

 cessive shrinkage occurs it has an adverse effect during the rolling 

 operation. 



The finished wire is inspected for dimensional limits, tensile strength, 

 elongation, and surface condition. The limits for 42 B. & S. gauge 

 wire (.002475 in.) are .00245 in. minimum and .0025 in. maximum. 



Conclusion 



The establishment of this industry as a part of the plant at Chicago 

 represents the combined effort of a large number of inventors, engineers, 

 designers, and mechanics. While the actual plant was built within a 

 comparatively short period, the advances which have been made in the 

 art represent several years' effort. Briefly, the development of com- 



CONYENTIONAL MECHANICAL 

 AND HANDLING PRACTICE 



inPROVED MECHANICAL 

 AND HANDLING PRACTICE 



MieETA ^3.SS4 5Q FT 



Fig. 26 — Wire drawing pltint 



pact and high speed wire drawing machines has required a much smaller 

 investment in buildings and equipment as compared with a plant of the 

 same capacity using commercial equipment. A comparison of the 

 relative floor area, based upon the conv^entional and the improved types 

 of wire drawing equipment, is illustrated by Fig. 26. The super- 

 visory force in charge of the operation of this new mill must be given a 

 considerable share of the credit for its successful operation. 



""Copper Refining," Lawrence Addicks. "Metallurgy of Copper," H. O. 

 Hofman. 



