In all casting processes, six basic factors are involved.
- A mold cavity, having the desired shape and size and with due allowance for shrinkage of the solidifying metal, must be produced.
- A suitable means must be available for melting the metal that is to be cast, providing not only adequate temperature but also satisfactory quality and low cost.
- The molten metal must be introduced into the mold in such a manner that all air and gases in the mold, prior to pouring, will escape.
- Provision must be made so that the mold will not cause too much restraint to the shrinkage that accompanies cooling after the metal has solidified.
- It must be possible to remove the casting from the mold.
- After removal from the mold, finishing operations may need to be performed to remove extraneous portions that are attached to the casting as the result of the method of introducing the metal into the cavity, or are picked up from the mold through contact of the metal with it.
