Have you ever wondered about what happens to the cavities undergoing a pressure of 800 to 1000 bars ?
We did it and this is the reason why, we are designing our tools so that for them to withstand at best the pressure, avoiding losses of centering which may occur when cavities undergo the pressure and also limiting at best the fatigue phenomena which could drastically shorten the tools lifetime.
The molds dedicated to gears require then very peculiar knowledges in terms of design.
It includes among others:
- the understanding of the tool behavior undergoing the injection pressure
- the steels selection on which depends also tools lifetime
- the kinematics of the tool
- its venting
Of course, up-to-date technologies such as 3D CAD, Moldflow analysis, FEA,.. are of valuable help to take up this challenge that consists in designing tools for precision gears but here again, the experience and the know-how of our design and tooling engineers remain our most important strength.
Plastic shrinkage is taken into account for the design of gear cavity. The tooth profile of plastic part isn’t the same as the one in the mold cavity. The modified tooth profile in mold depends on :
the processed plastic material
the position of the injection gates
the gear structure
the flow orientations…
Example of filling analysis for a gear: