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#111 Terminology and Surroundings (5) Die Height and Shut Height

Category : Terminology
February10, 2012

In a press machine, there is a maximum height of the die that can be installed. If this maximum height is exceeded, it is not possible to install the die in the press machine. There are two methods of expressing this height, namely, die height and shut height.

These are explained using Fig. 1. When the slide is at the bottom dead center position and the slide adjustment screw has been raised to the topmost position, the distance from the bottom surface of the slide to the surface of the bolster plate is called the "die height". When the bolster plate is removed from the press machine, the surface on which the bolster plate was is called the "head surface", and the "shut height" is the distance from this head surface to the bottom surface of the slide.
Some people might have thought that these two heights are the same, but they are not, and it is important to understand the difference between them. However, recently, since the bolster plate is almost never removed from the press machine, there may not be any problem if these two words are being used interchangeably.

[Fig. 1] Die height and shut height in a press machine

However, why this shut height is used is because in the olden days it was difficult to possess a press machine because it was very costly. In those days, the bolster plate was being changed to suit the application. For example, when carrying out a blanking operation, since the work becomes easy if the blanked part is made to fall through a hole in the bolster plate, a bolster plate with a hole at the center was being used. In compression forming, since it is necessary to firmly support the bottom die, a bolster plate without any hole in it was being used.

For the sake of reference, when a die lower than the maximum adjustable height is installed, it is easy to install the die if the height is within the adjustment range of the slide adjustment screw. In the case of a die with a height smaller than the adjustment range of the slide adjustment screw, the height is adjusted using spacers (which is normally a block called "Geta" in Japanese). The work of installing a die in the press machine is called "die setting up", and this height adjustment is a big factor that affects the time taken for this die setting up. As far as possible, the height of installation of the dies should be made uniform.

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