From: Blasch, Larry (LBlasch@OPW-FC.com)
Date: Thu Aug 22 2002 - 17:09:46 EEST
Ben,
We are using lost foam for some or our complex, thin-wall Aluminum castings
here at OPW.
It is a hybrid casting process that uses a machined or molded foam pattern.
The patterns are glued to a sprue and/or runner also made of foam, and then
dipped into a clay/ceramic slurry and dried (overnight) The clay/ceramic
coated assembly is then mounted into a casting barrel and loose sand is
showered around it until it is fully embedded. (You vibrate the barrel to
compact the sand) The molten metal is poured into the foam sprue and it
vaporizes the foam in a slowly moving wave and fills in the clay shell.
Dimensional accuracy is better than traditional sand casting and not quite
as good as investment casting.
Patterns are made in several ways, either molded from expanded polystyrene
beads in aluminum molds, or machined from extruded polystyrene foam. Getting
the foam density just right is the challenge.
The real beauty of lost foam is the complexity of the parts that can be
created. since the foam can be assembled and glued together, there is no
real limit to the part shape and size. I have heard of large casting
patterns being assembled in pits dug in the floor and used to make generator
engine blocks weighing thousands of kilos.
We work with Willard Industries in Cincinnati Ohio USA,
http://www.willardindustries.com/ <http://www.willardindustries.com/> and
their tooling specialist: the Austin Group at http://www.lostfoam.com/
<http://www.lostfoam.com/>
but I have also heard of http://www.richards-engineering.co.uk/Lostfoam/
<http://www.richards-engineering.co.uk/Lostfoam/> in the UK.
Sincerely,
Larry Blasch
Lawrence R. Blasch
Design Engineer
CAE Systems Administrator
OPW Fueling Components
P.O. Box 405003
Cincinnati, OH 45240-5003 USA
Voice: (513) 870-3356
Fax: (513) 870-3338
-----Original Message-----
From: Ben May [mailto:benmay@pdd.co.uk]
Sent: Thursday, August 22, 2002 6:11 AM
To: 'rp-ml@rapid.lpt.fi'
Subject: A bit off topic - lost foam sand casting
Greetings RP'ers
Anyone out there know anything about lost foam sand casting. Most people
I've spoken too seem to assume that it's an investment casting process
wheras I'm sure I've heard of it being used for sand-casting. I need to know
2 things:-
What grade of expanded polystyrene is typically used for the sacrificial
patterns?
Is there a foundry (preferably in the UK) that has experience of producing
large bronze components using this process?
Thanks in advance for your help
Ben May
Senior Development Manager
Pankhurst Design and Developments Ltd
85-87 Richford St
London W6 7HJ
Tel: 020 8735 1111
Fax: 020 8735 1122
benmay@pdd.co.uk
http://www.pdd.co.uk <http://www.pdd.co.uk>
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