Deep drawing

Wrinkles can be prevented by using a blank holder, the function of which is to facilitate controlled material flow into the die radius.

The forming load is transferred from the punch radius through the drawn part wall into the deformation region (sheet metal flange).

Due to material volume constancy, the flange thickens and results in blank holder contact at the outer boundary rather than on the entire surface.

Commercial applications of this metal shaping process often involve complex geometries with straight sides and radii.

In such a case, the term stamping is used in order to distinguish between the deep drawing (radial tension-tangential compression) and stretch-and-bend (along the straight sides) components.

Dies are made of cast light alloys and the rubber pad is 1.5-2 times thicker than the component to be formed.

It is a double-acting apparatus: at first the ram slides down, then the blank holder moves: this feature allows it to perform deep drawings (30-40% transverse dimension) with no wrinkles.

[4][5][6][7][8] Industrial uses of deep drawing processes include automotive body and structural parts, aircraft components, utensils and white goods.

Alloy steels are normally used for the ejector system to kick the part out and in durable and heat resistant blank holders.

Some examples of lubricants used in drawing operations are heavy-duty emulsions, phosphates, white lead, and wax films.