Re: INJECTION MOULDING

From: Jean-Marc Boéchat (jean-marc.boechat@mimsystems.com)
Date: Tue May 27 2003 - 09:39:50 EEST


Injection molding of gold does exist but at this point, as far as I
know, there is not commercial feedstock you can buy.

The problem that often bother, to say the least, the jewelry industry
with injection molding is the density. It is possible but not easy and
not very practical to get 100% dense parts by injection molding of
metal. What you should know is that the base metal is used in this
process in a powder form and then sintered. Hence the density reached is
under 100 % with the basic process. We get usually densities from 95 %
up to 99.7% of the theoretical density which in this case is not too
bad. But if you have less than 100% it means you have pores in the
structure. If you polish your surface the risk exists that a pore will
appear on the surface and ruin your day and your part!!!!.

I have seen an article in Metal Powder Report, vol 57 N0 12 (dec 2002)
page 18 describing a process to build gold ring with powder metallurgy
techniques. Maybe you should have a look at it.

Have a nice day, hope this helps

Jean-Marc

> ----- Original Message -----
> From: Mehmet SALIM
> To: rp-ml@rapid.lpt.fi
> Sent: Monday, May 26, 2003 1:49 AM
> Subject: INJECTION MOULDING
> Hello to all list,Does anyone know any kind of research or
> trials of making INJECTION MOULDING and INJECTION of Gold
> ?We are in Jewellery industry and the main problem with
> working rubber moulds for wax patterns to use in Investment
> casting is standardization of the part and the part weight.
> And the other problem is the air bulbs inside of the casted
> parts which make a bad outlooking on the surface of the
> part. If gold material can be used as Aluminium for
> injection it will be a revolution for jewellery
> industry....I am curious about if anyone out there is
> working on this subject or tried before... regards, Mehmet
> SALIM
>

--
Jean-Marc Boéchat               email:
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MIM Systems Ltd                 phone:+4126 430 08 08  fax: +4126 430 08
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