9 April 2019

Difference between open die forging and closed die forging

The method of deforming a piece of metal between various dies that does not fully enclose the material is open die forging. The metal is modified by a sequence of movements as the dies "hammer" or "stamp" material until the required shape is achieved. 

Let us have a deep insight into the difference between open and closed die forging.

Difference between open and closed die forging : 

  • Open die forging is also known as free forging, meaning metal billets compressed under the external compressive force and deformed to desired dimensions in a freeway without forging dies while closed die forging is also known as impression die forging, is a process that heated by medium frequency induction heating furnace to high temperature and forced between upper and lower dies to get expected shapes like the drawing.
  • Both forging processes are also different in the side of their processes. Moulding dies are firstly made for closed die forging, and then forged steel bars are placed on the dies and drop forged to desired shapes. In open-die forging, it involves enormous compressive force imposed by the continuous strike of a hammer to make the metal billets deformed. 
  • Open die forging will require further rough machining due to its free forging and imprecise dimensions may be reached by second precision machining while closed die forging is more common in small parts for its high precision used to make forged fittings, forged flange and forged automotive parts. 
  • The open die metal forged parts are more suitable for larger parts in a number of tons whereas for small parts closed die forging is preferred as high precision is obtained in closed die forging.