Re: Applications

From: Greg Redden (CSIRO  Institute of Industrial Technologies)
To: RP-ML
Date: Friday, March 17, 1995
Subject: Re: Applications
It seems strange to me that such an emphasis in being placed on the use of
investment casting, using RP patterns, for the production of hard tooling.
Granted, investment casting is often the most appropriate process for
producing complex metal parts, this is especially the case when the  part
has features such as undercuts. However investment casting (unlike Shaw
process or plaster casting) has the distinct disadvantage that for every
casting an expensive RP pattern is lost (in some instances tooling to create
waxes can however be used).

Why are few people using processes such as plaster and Shaw process casting
to produce multiples of parts or tooling?  One possible answer to this
question may be the loss of dimensional accuracy across parting lines in
such processes. (Parting lines are necessary in order to recover patterns).
This answer is not however valid for tooling applications where such parting
lines will not affect the critical dimensions of a tool.  In fact over the
past forty years many more tools have been cast in steel using the Shaw
process than using investment casting.

I invite comment.
Greg Redden