 Two dies are used in die casting ; one is called the " cover die half " and the other the " ejector die half " . Where they meet is called the parting line . The cover die contains the sprue ( for hot @-@ chamber machines ) or shot hole ( for cold @-@ chamber machines ) , which allows the molten metal to flow into the dies ; this feature matches up with the injector nozzle on the hot @-@ chamber machines or the shot chamber in the cold @-@ chamber machines . The ejector die contains the ejector pins and usually the runner , which is the path from the sprue or shot hole to the mold cavity . The cover die is secured to the stationary , or front , platen of the casting machine , while the ejector die is attached to the movable platen . The mold cavity is cut into two cavity inserts , which are separate pieces that can be replaced relatively easily and bolt into the die halves . 
