In drawing operations, the product that has entered into the die is pushed out by using a knock out as shown in Fig. 1. At that time, if the material of the product is soft, the plate thickness is small, and also if the shape is such that the shoulder radius of the bottom part (the punch shoulder radius) is large, the bottom of the product becomes deformed if the product is pushed out using a knock out with the shape as shown in Fig. 2.

In the case of such products, the shape of the knock out is made to match with the bottom radius of the product as shown in Fig. 3, and the product is pushed out not at the bottom of the product but at the stronger shoulder radius part of the product. If the die design is made with a simplistic thinking that it is sufficient if the knock out just pushes out the product, you will meet with failure in such situations.