RE: Rapid Mold Making

Date: Fri Nov 14 1997 - 01:54:34 EET


> Is LOM used to make master patterns for investment casting?
I have used LOM for investment casting two ways: directly and

Indirectly, I have been able to make molds for wax directly on the LOM.
Thorough finishing is important to seal the paper from the moisture of
the wax. This only works for simple geometries like an auto door hinge,
pump rotors, etc. Failure mode is delamination of mold after 50 or so
shots of paste wax.

Directly, I have make several parts where the LOM part is the
investment. One must burn out the LOM pattern at 2000F for about 8
hours, and use about 4 times the normal amount of gates. But it does
work. It does not seem to be geometry dependent, but again finishing is
important: only use wax for repairs (not putty, leaves residue in
shell), only use lacquer for sealing (others leave residue also). Main
failure mode was poor finishing allowed slurry to leech into the LOM
part causing expansion & shell breakage upon firing.

> Regards,
> Dan Davis
> Division Head, RP&M
> Perusahaan Otomobil Nasional Berhad (PROTON)
Hicom Industrial Estate
Batu 3 PO Box 7100
Shah Alam, Selangor D. E.
> +60 3 511-1055
> +60 3 515-2380 direct fax

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