In case you are interested in the deep drawing process, and you want to establish a business based on it, you should make sure that you provide your clients high-quality products. During the deep drawing, a punch pushes the metal sheets into a form, and the result is a part with a defined contour. For a product to be considered deep drawn its depth has to be half of the item’s diameter. In case the depth of the depth does not have this size then the item is made with deep drawing stampings, and the process is called general stamping. There are many companies that use deep draw stampings to manufacture a wide variety of household products, such as battery casings, soup cans, kitchen sinks and even fire extinguishers. During the deep draw manufacturing process, there are involved multiple operations, according on how complex the items resulted is. However, as a manufacturer you have to be sure that your products will not be deformed by wrinkling, because it is crucial to provide only high-quality products to your partners and customers.
What causes wrinkling?
For being able to fix this issue, you have to know what the factors that lead to wrinkles in the deep drawn items are. Here is a list with the most important ones:
- Die cavity radius and depth
- Blank holder pressure
- Friction between the blank holder, blank, die cavity and punch
- Resulted part geometry
- Blank thickness and shape
- Punch speed
There are also factors as the alloy of the blank and the die temperature that will influence the drawing process, so make sure you pay attention to all of them.
What methods can I use to prevent wrinkling?
If you are looking for a simple method, then you should use a blank holder. During the deep drawing process, a blank holder pressure is applied. But if you are using a hydraulic or pneumatic blank holder cushion you can vary the pressure linearly over the action made by the machine. During the drawing action, you can use a numerically controlled die cushion to provide a variable pressure. In addition, you can use the die cavity design method. The design of the die cavity and punch can be optimized in such a way to reduce the probability of wrinkling. One option would be to choose a large enough flange radius, which will minimize the potential of wrinkles and will prevent cracking. Also, you should know that sometimes asymmetry works. If you opt for a multi-step drawing process, you will minimize the probability to obtain wrinkled deep drawn parts. The potential of wrinkling can be reduced if the excess material is minimized. The stresses of the metal blank will vary according to the orientation of the grain and of the design of the die. You should consider adjusting the grain to obtain an asymmetrical design.
What other factors should I consider?
If you want to improve the overall performance, then you should tailor the surface conditions of every one of the components. You can use lubricants to reduce the friction between the punch, blank and die cavity. You should apply lubricants to the blank before starting the deep drawing process.