Re: zinc castings

From: Mnr. D de Beer (DDEBEER@ENG.TOFS.AC.ZA)
Date: Wed Jul 16 1997 - 10:40:56 EEST


Jeff

I am not sure what you have in mind, but I would start looking for
someone active in "spincasting" (or centrifugal rubber mould
casting). We have our casting system in operation for just over a year
now, and can report very good products (replicas made in zink or other low melting-
point alloys - various products to suit different needs).

This method is somewhat unique compared to investment casting, as
your master (prototype) remains in tact for further use if necessary.
A further advantage is the price - a fraction of the price of other
processes.

Dependent on the number of replicas needed, there would be different
options:

The traditional route would be to make an RTV mould for spincasting,
to produce a number of masters, which will bet used in a production mould
(vulcanised silicone mould). This opens up the door for a lot of
different RP technologies, as models made in almost any material
(wax, paper, epoxy, etc) can be used as a master pattern.

 Again, the planning of a master mould will depend on the part size and geometry.
(sometimes only one part will be used in a production mould) However, we have
 succeeded in making vulcanised moulds directly from SLA patterns - even though
the temperature exceeds the glass-transition temperature of the epoxy resin. Up to
now we had our SLA patterns made by a service bureau - thus limiting
 experimentation due to the cost thereof, but our SLA machine is being shipped at
this moment, and work in this area will continue.

I will keep you posted on our progress once our machine is
operational.

Deon de Beer
Faculty of Engineering
Technikon Free State
South Africa



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