1070 THE BELL SYSTEM TECHNICAL JOURNAL, SEPTEMBER 1953 



CARD ENGAGING MEMBERS 





GRiPP r-jG TR!GGER 



PROTECTING EDGE 



Fig. 22 — Bulk card handling tool. One side plate has been removed to show- 

 cards. 



The card material had to be magnetic so that electromagnets could 

 be used to assist in the manipulation required in the course of a transla- 

 tion. After giving due consideration to the use of permalloy, Armco 

 iron and several other materials it was concluded that the most prac- 

 ticable compromise would be to use hard-rolled AISI-C1008 strip steel. 



The protective finish selected was chromium flash over nickel-plate. 

 The nickel provides reasonable protection against corrosion, while the 

 chromium provides surface characteristics consistent with the need for 

 maintaining interface friction and wear at low levels. The finishes are 

 applied to the strip stock by a continuous plating process and it may 

 be interesting to point out that the current value when applying the 

 chromium is in the order of 1,000 amperes. It will be realized, therefore, 

 that one of the problems in producing satisfactory material is main- 

 tenance of the rolls over which the material is fed and which also are 

 circuit elements, free from foreign materials because otherwise high 

 resistance points may develop and cause burning. 



Flatness is important because any deviation from a plane, in effect, 

 increases the thickness of the card and thus limits the card capacity of 

 the translator. Manufacture is controlled so that the slight bowing that 

 results from handling the material in rolls always is in the same direction 

 as the material is fed to the perforating and blanking tools. Out-of- 

 flatness is held to maximum 0.012" within 72 hours after fabrication. 

 Bowing subsequently increases the out-of-flatness but not to an im- 

 portant extent. The out-of-flatness is checked by means of the gauge 

 illustrated by Fig. 23, which was developed especially for the purpose. 



