WlUK STK AKilirKNINc; AND MOl.Di.Nd FOK KELAY.S 875 



Fig. 11 — Cutaway sections of resin blocks showing inadetiuate versus adequate 

 wire supports in molding die. 



with no significant experience in molding closely spaced arrays of small 

 diameter wires into phenolic resin. The initial effort demonstrated con- 

 vincingly, Fig. 11, that small diameter wires cannot be embedded in 

 i-esin b}' high pressure molding techniciues without the liberal use of 

 wire supports. These are needed to prevent indi\idual wires from being- 

 deformed by the pressure of the plastic as it is forced into the cavity. 

 One fundamental observed in die design subseciuently was to keep all 

 wire spans inside die cavities as short as possible. 



As expected, early studies demonstrated that lack cf cross sectional 

 symmetry caused combs to have a marked tendency to warp. While 

 warping could be reduced by increasing the time the resin was retained 

 in the molding cavity, this partial solution was unsatisfactory from the 

 standpoints both of warpage and product cost. Accordingly, every effort 

 was made, consistent with rela}^ design recjuirements, to depart as little 

 as possible from symmetrical die cavity design and where symmetry 

 could not be achieved, to attempt to distribute the resin mass uniformly 

 on each side of the center line of the wires. 



The importance of symmetry, together with the desire to keep molding 

 Hash to a minimum, influenced Western development engineers to design 

 the earlier experimental die cavities Anth the wire inserts centered at the 



