Question

List the similarities and differences between direct extrusion and drawing. (please explain with details)

Answer 1

similarities between direct extrusion and drawing

1) both are plastic deformation process which takes beyond yield point of the material . it is also called metal forming

process.here in the plastic deformation zone, change in volume before and after the operation remains same and

poisson's ratio will always equals to zero.

2) in both, nature of strese induced includes compressive stress. in direct extrusion, triaxial compression is induced

whereas in drawing biaxial compression and tension is induced .

3) mostly ductile materials are preferred for these type of operations. Because of the ductile nature of the material ,

it can be easily modified with less force.

4) as the force is applied , first force increases to maximum value and after that molten metal moves in the radial

directions in both the cases. So because of this, in direct extrusion 16% molten metal is wasted and can not be

used for extrusion and in drawing side wall increases in thickness as the height is increased.

5) surface finish obtained by both the operations are very good and also dimensional precision is better.