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#137 Design of Blanking Dies (10) Design of a Blanking Die

Category : Shear Forming
December 7, 2012

Figure 1 shows the structure of a standard blanking die. A die is a very important part that creates the shape of the product.
The die hole machined in the die (die plate) is prepared with the shape of the product. In the case of a blanking die, the shape obtained after the material passes through the die hole becomes the product.

Fig. 1

■ One point Explanation: "Die" as a difficult to understand terminology

The word "die" is used in various ways. Some of them are the following.

1. Firstly, it is used to represent the entire press forming die set, e.g. blanking die.
2. As is being explained here, the part with a shape that receives the punch is also called a "die". This is the meaning when we say, "the die cutting edge tip is worn".
3. Sometimes a "die" may also refer to the plate that constitutes the above mentioned shape. This is the meaning when we say "grind the die because it has worn", etc. Actually the plate from which a die is constituted ought to be called a "die plate".
4. Apart from these, there is also a word called "insert die". This implies a part that is assembled inside a die plate and constitutes the die shape. Even the word "button die" has a similar meaning.

A person who can understand the different meanings of this word "die" can be said to have understood press forming quite well.

Coming back to the main topic, when determining the dimensions of the die, it is necessary to consider the blanking clearance. SeeLesson No. 5in which this blanking clearance has been explained.

In a blanking operation, a sideward force acts during blanking. The die plate breaks (cracks) if the distance from the circumference of the die to the outer periphery of the plate becomes small. Fig. 2 gives a guideline for the distance from the circumference of the die to the periphery of the plate.


While the above applies to the planar shape, it is also necessary to consider the cross-sectional shape (the shape as viewed from the thickness direction of the die plate. When the material is passing inside the die, it is good if it does not scrape against the inner surface of the die for too long. As an example, the cross-section of a die becomes as shown in Fig. 3. It is better that about three or four products stay inside the part of the die indicated as "s" and any additional products fall down.


There are several types in the method of preparing the cross-sections of such dies. This has been explained in detail in Lesson No. 6 about the shape of blanking dies.

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