NEW GEXKHAL ITRPOSK UKLAY 



1011 



cooling period as the wekl is completed. A small resistance u is adde(l 

 ill series with the discharge circuit to limit the curiciit and control the 

 arcing period. 



That high weld strengths are obtained by this process is indicated in 

 Fig. 15 which shows typical distributions of Aveld strength for both the 

 percussive-welded contacts and the spot-welded twin contacts. The plots 

 show the percent of contat'ts with weld strengths e(iual to or less than 

 any prescribed value Axitliin the range of the chart. As shown, the per- 

 cussive welds are generall}^ stronger than the sj)ot welds which is, in 

 part, due to larger welded areas. 



Although percussive welding is more suitable for the stationary con- 

 tacts welded in the factory, it is planned that occasional replacement of 

 both stationary and twin contacts will be made in the field by spot 



POWER SUPPLY 



-Wv — I 



AW 



R 



CONTACT 



'Jlr^ 



MOTION I I 



H= 



\ STATIONARY 

 WIRE ASSEMBLY 



Fig. 14 — Diagram showing the essential elements of the percussive welding 

 process used for the stationary contacts. 



welding. Tliis will be done with the Bell System field welding eciuip- 

 ment^ provided with suitable electrodes. In this case, however, more 

 expensive all-palladium stationary contacts of special shape would be 

 used to facilitate the spot welding and individual hand adjustment for 

 final position of the contacts will be necessary. 



8. STANDARDIZED ASSEMBLY OF CODED PARTS 



Since assembly was one of the most promising fields for reducing costs 

 in a new relay design, special effort was made to reduce the assembly cost 

 of the AF relay. Some of the major design features which contribute to 

 low cost assembly are: 



1. The continuous molding and fabricating processes for the wire 

 spring subassemblies, Avhich avoid all individual handling of wires and 

 contacts. 



9W. T. Pritchard, "Relav Contact Welder", Bell Lab. Record, April, 1044, 

 p. 374. 



