3 Fundamentals of press design

Principles of die manufacture
Fig. 4.1.18 Polystyrene pattern of a die
Compared to the use of other pattern materials such as wood, metal,
or plastic, the designer is not restricted by the limitations of the conventional
casting technology. As the pattern remains inside the form,
there is no need to consider the parting line, undercuts, conicity and
the tapers for pattern removal.
All ferrous materials are suitable as casting material for production
dies. The residual matter left over from the vaporisation of the pattern
impairs the finish of the surface quality of the die only to a minimal
degree. However, in order to ensure that the operating surface of the die
can have the best surface quality, this surface is placed face down in the
casting box. The maintenance of the pattern during fabrication presents
no problems – with a specific weight of 20 kg/m 3 , even large polystyrene
patterns can be transported without having to use large cranes.
Compared to conventional preparation methods such as welding, casting
techniques have the following advantages:
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