 Hot @-@ chamber die casting , also known as gooseneck machines , rely upon a pool of molten metal to feed the die . At the beginning of the cycle the piston of the machine is retracted , which allows the molten metal to fill the " gooseneck " . The <unk> or hydraulic @-@ powered piston then forces this metal out of the gooseneck into the die . The advantages of this system include fast cycle times ( approximately 15 cycles a minute ) and the convenience of melting the metal in the casting machine . The disadvantages of this system are that it is limited to use with low @-@ melting point metals and that aluminium cannot be used because it picks up some of the iron while in the molten pool . Therefore hot @-@ chamber machines are primarily used with <unk> , <unk> , and lead @-@ based alloys . 
