HOME  > Plastic Molding Tutorial  > #051 Method of Connecting the Cavity and Core
Plastic Molding Tutorial

#051 Method of Connecting the Cavity and Core

Category : Cavity
July23, 2010

Usually the cavity and the core are connected to the mold plate of the mold base, but some typical of the other fastening methods are shown below.

Explanatory diagrams of the examples of four types are shown in Fig. 1.

Fig. 1 Methods of connecting the cavity and the core

A. Bolt connecting

Bolt connecting is the method used frequently in large molds in which there is enough space to provide screw holes and bolt fixing holes in the cavity and the core. It is possible to fasten strongly because of the screw. It is possible to consider the method of tightening the bold from the parting surface side or the method of bolt tightening from the side of the mold plate back surface. The direction of bolt tightening is selected suitably depending on the conditions.
For the screw, usually metric coarse thread is used.

B. Flange retaining

Flange retaining is the method used when sufficient space is not available for provided screw holes and bolt fixing holes in the cavity and core.
Usually, the two methods of double side flange and single side flange are used. The amount of catching by the flange is about 1 to 2mm, and the height of the flange is about 3 to 10mm, and the selection is made depending on the size of the core.

C. Key retaining

Key retaining is the method used when fastening several components in which case it is difficult to use the flange retaining or the bolt fastening methods.
The shape of the key can be that of the bracket character "]", straight key, round key, etc.
It is necessary to consider the dimensions of key mating.

D. Press fitting

Press fitting is a mold fastening method that is used very frequently in the case of large molds. The external dimensions of the cavity and core are machined so that they fit tightly in the pocket carved from the parting surface side, and the press fitting is made by hitting with a plastic hammer, etc.
If this method is used, since the dismantling of the cavity and core becomes difficult at the time of maintenance, sometimes a hitting hole is provided in the bottom surface of the pocket for dismantling.

MISUMI USA eCatalog