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#113 Terminology and Surroundings (7) Insert Dies

Category : Terminology
February24, 2012

Insert type die shown in Fig. 1 is a generic name given to die using an insert type plate. Insert type plates are used frequently as die plates or as stripper plates. Very often dies using this type of plates are called precision dies, and from the point of view of accumulation of error, the positioning accuracy is lower compared to integrated dies. The reasons why they are considered precision in spite of this are the following.

  1. It is possible to machine the inserted components with high accuracy.
  2. It is possible to adjust the positioning accuracy by moving the insert plate.

[Fig. 1] Plates of insert type dies

In recent precision dies, it has become very common to assemble the dies with the stripper as the reference. Stripper reference means that the relationships such as the tolerances, etc., are adjusted by adjusting the die to correspond to the punch which is guided by the stripper. The adjustment becomes easy because of using the insert type. The changes in the method of preparing inserts are explained below.

  1. Although the shape of the hole for an integrated block type insert is prepared by the wire cut electric discharge method (WEDM), etc., which is not different from the method of preparing an integrated type insert. This is used when wanting to increase the positioning accuracy.
  2. A split type insert is intended to be prepared by machining the shape by grinding. This is used for increasing the accuracy of the shape of the hole or for increasing the accuracy of the second draught, etc. The positioning accuracy is the same as that of integrated type inserts.
  3. Inserts using spacers are designed for the purpose of making it easy to adjust the positioning accuracy. The positioning adjustment of inserts is made using shims (thin plates). Expertise is required for the handling of shims. This can be said to be an insert type which has been improved by making it easy to carry out adjustments using thick spacers. Position adjustment is not possible in the case of round inserts.

In the case of insert type dies, when the tip of a die gets worn out, only the insert is ground. The level is adjusted by putting a shim corresponding to the extent of grinding. In the case of integrated type inserts, since the grinding is done entirely, the die height changes.
In the case of insert type dies, by using materials with high wear resistance (cemented carbide, etc.) for the inserts, it is possible to extend the life of the dies.
Although round blocks are suitable from this aspect and are suitable for regrinding, there are problems in using them from the point of view of increasing the positioning accuracy.

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