Abstract
This paper presents a review on the effect of friction
during forging operation; must especially the double cup extrusion
process. The metal forming process, such as forging, is one of the
manufacturing processes where metal is pressed or forced under great
pressure into high strength parts. Before the process, lubricant is
applied to the dies in operation to promote the flow of metal, to
reduce friction and wear, and to aid in the release of the finished part.
Interfacial friction between the forgings dies and the workpiece such
as billet has a significant effect on the forging applications, forming
quality, and deformation loads. The most commonly used lubricant is
liquid based lubricant, such as water-based graphite, synthetic oils,
liquid soap, shear butter etc. Under the high pressure condition and
reductions of the lubricant film often breaks down the operation and
caused poor metal flow and wears. High interface friction is a
primary cause for adhesive pickup in cold forging.