MACHINING OF CASTINGS

Castings are among the most popular semi-products used in the industry. Their popularity results from casting technology and the extensive possibilities it gives for designing structural elements. The basic benefit is the possibility to obtain complex shapes and save the material in large batches of identical parts. Casting is a method of producing products which consists in filling molds with molten metal that solidifies to keep the shape defined in the molten state.

A typical process of casting production covers five subsequent stages:

  • production of product model
  • production of casting mold
  • preparation of molten metal to fill the mold
  • filling the mold
  • parting the mold and finishing the casting

Solidified and cooled castings are knocked out of the molds, the cores are removed, the castings are cleaned of the molding sand, gating and sprue elements are cut off. Castings removed from the mold usually require finishing which could include cutting off the gating elements of flow-offs and various surpluses with the use of chisels or pneumatic hammers. Next, the castings are cleaned to remove the remains of molding sand from the surface by drum cleaning or sand blasting. Some castings are heat-treated in order to reduce their hardness prior to machining or to improve their strength.

The last stage of the casting process is the mechanical treatment of the finished casting. The process involves the machine removal of designed allowance areas in critical points for product design, geometry and the dimensions of which cannot be achieved with casting technology. The mechanical processing of castings is often a complex process that requires experience and knowledge. The main problem in this case is the stable and reproducible fixing of the casting for machining due to inclinations, thin walls or complex geometry.