What Is Deep-Draw Stamping Process?

It has long been known that stamping is an economical way to produce complex parts. Although the initial cost of stamping die is relatively high, deep-draw stamping process is usually cheaper and faster than processes like machining, casting, and forging. Deep-draw stamping process is capable of producing parts that are longer or deeper than those made by traditional stamping.

Understanding of deep-draw stamping process

Deep-draw stamping process is a form of metal stamping in which drawing is usually greater than its diameter. In practice, long and narrow cylindrical parts with length significantly greater than the outside diameter of the part can be produced. Traditional stamping processes cannot achieve such deep stretching because the material cannot be fully stretched, resulting in uneven, thinning, and tearing of the walls. In deep drawing, this challenge is overcome with careful tool design that forces the material into the die in the initial stage of the process. This ensures that enough material is available to achieve the final shape while maintaining the desired wall thickness.

How does deep-draw stamping process work?

The drawing is carried out in several stages. In the first stage, the blank will be forced into a cup shape with a diameter greater than the final part diameter. In subsequent stages, the part diameter gradually decreases and the depth increases. The tool is usually combined with some form of part transfer so that all operations are performed on one press. With these techniques, parts can be manufactured using deep-drawing methods that are more than ten times longer than their outside diameter.

The design of the deep drawing die is critical. Special care must be taken to ensure that over-stretching does not occur, so initial die and punch radii must be carefully calculated. If the die radius is too small, the material will not flow properly, and if it is too large, wrinkling will occur. All tools should be highly polished to aid material flow and high strength tool steel should be used for the radius at the die entrance. The gap between the cup and the tool is also critical to ensure the correct final ratio of stretching, flow, and work hardening. Press speed is important because if it is too high, corner cracking will occur, but if it is too low, material flow will be affected.

Advantages of deep-draw stamping process

The deep-drawing stamping process has two major advantages. First, the output is high, limited only by press speed, with press capacity typically exceeding 2,000 pieces per hour. Second, the achieved smoothness does not require further machining, and secondary operations such as flanging, grooving, chamfering, and perforating can be performed in the deep drawing die. Considering both the mold cost and the high-output nature of the process, the cost per part is low.