Deep drawing is a sheet metal forming process in which a sheet metal blank is radially drawn into a forming die by the mechanical action of a punch. It is thus a shape transformation process with material retention. The process is considered "deep" drawing when the depth of the drawn part exceeds its diameter. This is achieved by redrawing the part through a series of dies. The flange region (sheet metal in the die shoulder area) experiences a radial drawing stress and a tangential compressive stress due to the material retention property. These compressive stresses (hoop stresses) result in flange wrinkles (wrinkles of the first order). Wrinkles can be prevented by using a blank holder, the function of which is to facilitate controlled material flow into the die radius.
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. Deep drawing is always accompanied by other forming techniques within the press. These other forming methods include:
Beading: Material is displaced to create a larger, or smaller, diameter ring of material beyond the original body diameter of a part, often used to create O-ring seats.
Bottom Piercing: A round or shaped portion of metal is cut from the drawn part.
Bulging: In the bulging process a portion of the part's diameter is forced to protrude from the surrounding geometry.
Coining: Material is displaced to form specific shapes in the part. Typically coining should not exceed a depth of 30% of the material thickness.
Curling: Metal is rolled under a curling die to create a rolled edge.
Extruding: After a pilot hole is pierced, a larger diameter punch is pushed through, causing the metal to expand and grow in length.
Ironing / Wall Thinning: Ironing is a process to reduce the wall thickness of parts. Typically ironing should not exceed a depth of 30% of the material thickness.
Necking: A portion of the part is reduced in diameter to less than the major diameter.
Notching: A notch is cut into the open end of the part. This notch can be round, square, or shaped.
Rib Forming: Rib forming involves creating an inward or outward protruding rib during the drawing process.
Side Piercing: Holes are pierced in the side wall of the drawn part. The holes may be round or shaped according to specifications.
Stamping / Marking: This process is typically used to put identification on a part, such as a part number or supplier identification.
Threading: Using a wheel and arbor, threads are formed into a part. In this way threaded parts can be produced within the stamping press.
Trimming: In the Trimming process, excess metal that is necessary to draw the part is cut away from the finished part.
Often components are partially deep draw in order to create a series of diameters throughout the component (as in the image of the deep draw line). It common use to consider this process as a cost saving alternative to turned parts which require much more raw material.
Punches and dies are typically made of tool steel, however cheaper (but softer) carbon steel is sometimes used in less severe applications. It is also common to see cemented carbides used where high wear and abrasive resistance is present. Alloy steels are normally used for the ejector system to kick the part out and in durable and heat resistant blankholders.
--- from wikipedia