 Other die components include cores and slides . Cores are components that usually produce holes or opening , but they can be used to create other details as well . There are three types of cores : fixed , movable , and loose . Fixed cores are ones that are oriented parallel to the pull direction of the dies ( i.e. the direction the dies open ) , therefore they are fixed , or permanently attached to the die . Movable cores are ones that are oriented in any other way than parallel to the pull direction . These cores must be removed from the die cavity after the shot solidifies , but before the dies open , using a separate mechanism . Slides are similar to movable cores , except they are used to form undercut surfaces . The use of movable cores and slides greatly increases the cost of the dies . Loose cores , also called pick @-@ outs , are used to cast intricate features , such as threaded holes . These loose cores are inserted into the die by hand before each cycle and then ejected with the part at the end of the cycle . The core then must be removed by hand . Loose cores are the most expensive type of core , because of the extra labor and increased cycle time . Other features in the dies include water @-@ cooling passages and vents along the parting lines . These vents are usually wide and thin ( approximately 0 @.@ 13 mm or 0 @.@ 005 in ) so that when the molten metal starts filling them the metal quickly solidifies and minimizes scrap . No risers are used because the high pressure ensures a continuous feed of metal from the gate . 
