WIKE STUAIGHTENINO AND MOLDING FOK RELAYS 877 



die parting lino. In the course of die d(!V(4opment work it ])eeame ap- 

 parent that reduction in l)oth die cost and the construction time could 

 be effected in some instances by confining the grooves for locating and 

 supporting the wire array to one half of the die cavity. This type of 

 design had the added ach'antage of eliminating annoying problems relat- 

 ing to precise registration of the upper and lower die halves during the 

 molding operation. 



The design of the die cavities now used for high production molding 

 represents development work based on such considerations as those 

 outlined above. The die cavities are similar but not the same for both 

 twin and single wire combs. They differ in the location of the parting 

 line which is flush with the top of the wire array in the twin wire comb 

 die and principally at the center line in the single wire comb. The latter 

 arrangement was dictated by two considerations, (1) Use of a U shaped 

 groove in one half the die cavity for a wire as large as 0.040-inch diameter, 

 resulted in excessive molding flash and (2) The chance of obtaining com- 

 pletely filled fins on both sides of the forward block was enhanced by 

 centering the wires. 



THE DIE 



Fig. 12 shows the lower half of the complex automatically operated 

 four cavity die which was evolved from simple single cavity hand loaded 

 units. That this evolution may not be completed is indicated by the 

 fact that the section of the die operated by the air cylinder shown at the 

 top of the photograph and intended to remove molding flash from the 

 \nres is no longer used. Much better flash removal is effected by blasting 

 the combs with ground walnut shells after the molding operation has 

 been completed. The operation of the automatic die, as related to the 

 manufacture of single wire combs containing twelve 0.040-inch silicon 

 copper wires, will be described under five sub-heads in the same sequence 

 as the progression of the wire array through the five sections of the die. 

 Similar progressive operations are performed in making twin wire combs. 

 The die consists of an upper half attached immovably to the head of the 

 press and a lower half mounted on a hydraulic ram wiiich raises and 

 lowers to close and open the die. 



WIRE GUIDING 



The single wire comb die uses one 24-double head wire straightener. 

 Fig. 13 shows how^ twelve continuous strands of wire from the straight- 

 ener are guided to the required spacing in each comb array. Spring ten- 



