The Bell System Technical Journal 



Vol XVIII April, 1939 No. 2 



Some Ceramic Manufacturing Developments 

 of the Western Electric Company 



By A. G. JOHNSON and L, I. SHAW 



A general picture is given of the development work involved in 

 the introduction of manufacturing processes for vitreous enameled 

 resistances, vitreous enameled iron and copper base number plates, 

 pressed glass lenses, extruded and pressed porcelain parts, and 

 close tolerance ceramic insulators for use in telephone apparatus. 

 The reasons for undertaking the manufacture of these products, 

 some of the major problems encountered in developing suitable 

 processes, and the work done in overcoming these difhculties includ- 

 ing several major contributions to commercial methods of manu- 

 facturing similar parts are described. 



ORIGINALLY, the ceramic parts used in the telephone and 

 associated equipment were not manufactured by the Western 

 Electric Company because the technical requirements and volume of 

 consumption of such parts did not warrant the development or estab- 

 lishment of processes or the facilities for manufacture. The later 

 development of such manufacturing processes for some of the ceramic 

 parts has been necessitated largely by inability to secure an adequate 

 supply of parts meeting the close limits required for satisfactory 

 functioning of the apparatus, although there have usually been other 

 influencing factors. Such developments have, in most instances, 

 been advantageous from an economic standpoint. The experimental 

 work has been confined to that required for the above ends and 

 only a very limited amount of research work has been done. Some 

 of the major projects for which it was necessary to develop new methods 

 of processing to obtain the desired quality at a satisfactory cost are 

 outlined. 



Switchboard Lamp Cap Lenses 

 The first major project undertaken was the development for manu- 

 facture of switchboard lamp cap lenses of the types shown in Fig. L 

 One factor necessitating this undertaking was the difficulty experienced 



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