COLD FORMING

 

The art of extruding and forging

Cold forming (emanation of cold forging) carries out in a combined way or not two moulding operations,  that model a blank in wire drawing metals by plastic deformation.

It concerns:

• Forging: The strain applied to the end of the blank, contained between the punch and the die, allows the material to exceed its elastic limit and causes its deformation.   The blank diameter increases by compressing its length.

• External extrusion:(also called extrusion or direct extrusion) or internal (also called drilling or back extrusion): the metal  forced under the pressure of the  punch flows through a drawing die or extruding die in the case of extruding or along a drilling needle contained in the die in the case of back extruding.

The importance and advantages of the process.

The cold formed parts have improved physical properties particularly if we compare them with their principal competing techniques: turned parts.

• The threading which is continuous and follows the contour of the part considerably increases the resistance to fatigue.

• The peening caused by the cold forming increases the mechanical resistance, the elastic limit and the hardness but at the same time decreases the constriction and the lengthening.

Moreover, this technique offers a good dimensional accuracy, an important surface consistency, an excellent repeatability and a very good productivity.