Deep drawing

Deep drawing is a sheet metal manufacturing process. This operation transform a flat sheet blank into a three dimensional part. Usually the depth of the drawn part exceeds its diameter it is the reason why this process is called “deep”.

The way to carry out a deep drawing process is with a punch and a die. The punch has the desired shape of the base of the part. The die cavity matches the punch and is a little wider to allow for its passage, as well as clearance. Clearance must be enough to avoid cut the sheet and allow the material flow.

Sheet metal piece, called blank, is hold over the die opening by pressure apply by a blank holder. The punch travels towards the blank. The punch forces the sheet metal into the die cavity, forming desired shape. Parts manufactured by deep drawing cannot be complex shapes, being necessary do the process in several phases for complex parts.

Hydraulic or mechanical presses are necessary to carry out this industrial process. Hydraulic presses can control blankholder and punch separately but the mechanical presses are usually faster.

Deep drawing has a big production rate and a very good dimensional precision, but also generates too much strain on the material may cause defects as wrinkling or fractures. To prevent these defects is necessary to ensure a n acceptable draw ratio, a proper lubricant and a correct holder force.