[Illustration: Fig. 32. Die-casting Mold shown in Fig. 31, disassembled]
Before taking up the actual machining operations of the mold-making as conducted in this factory, it will be well to take a typical die-casting mold and note its general construction. Fig. 31 shows a typical die-casting mold closed, while Fig. 32 shows the same mold disassembled on the bench to show its construction. The piece for which the mold has been made is also shown. Fig. 33 shows a similar die in section. From the three illustrations a good idea of an average die-casting mold can be obtained. Referring to these illustrations, the principal parts of this die are the ejector box _A_, and the ejector plate _B_ which is operated by the racks _C_. For operating the ejector plate, the pinion shaft _D_ having a handle suitable for turning, is furnished. This, of course, fits into a bored hole in the ejector box, bringing the pinion into mesh with the racks for raising the ejector plate. In the ejector plate are three ejector pins _E_ for removing the casting from the mold. The ejector pins operate through holes _F_. Beyond the pinion shaft may be seen the casting for which this mold has been made. It will be noticed that the top side of the casting has three projecting lugs through which are small holes. Provision for forming this side of the die-casting is made in the lower half of the mold _G_, while the upper half of the die-casting is taken care of by the top plate _H_. One of the toggles for operating the core pins through these three lugs is shown at _I_. These parts will be described more fully later. The sprue cutter is shown in position in the die at _J_.
As will be noticed from Fig. 30, the machinery in the die-making department is of modern design, for no other class of work demands as good tool equipment and as much skill in the making as die-casting molds. The die-blocks are made of machinery steel. Fig. 34 illustrates the first step in making a die-casting mold after the die-block has been shaped approximately to size. This operation consists in carefully facing off the die surfaces on a vertical-spindle grinding machine. This, of course, is a quick method of surfacing the die-block, and it insures that the top and bottom surfaces of these plates will be parallel, permitting the die-faces to come together properly.