lost foam sand casting

From: William Bankes (bbankes@globalms.com)
Date: Thu Aug 22 2002 - 15:31:38 EEST

A bit off topic - lost foam sand castingAs a member of the list, the lost
foam process is our main rapid prototype method. We work with several
investment cast foundries to generate castings using both EPS (expanded bead
polystyrene) and extruded Dow board polystyrene.

We have provided pattern as large as 9 ft in diameter for an aluminum
foundry, to a 4in diameter impeller part. The metals include aluminum, grey
iron, steel, bronze. The process we have seen success with includes putting
a wax on the surface and dipping the part in a ceramic. The foam is then
heated slowly to allow the foam to shrink and be removed or fired up to
completely burn the pattern out.

The savings in this process comes from:

1. Avoiding the tooling process. Typically a steel tool is fabricated 4-12
weeks lead time to inject wax into to make wax investment patterns.Tooling
$5000 - $20,000 not unusual.

2. The ability to experiment with various sizes from part to part.


1. Not very many foundries will do this type of lost foam process.
2. Surface finish can be rough.
3. Tolerances in foam at +/- 20 thousanths.

With the proper technique we have seen castings that we as smooth as a wax

William Bankes
Global Manufacturing Solutions
9562 North Dixie Hwy
Franklin, Oh 45005
866-897-4894 Toll Free
937-743-9944 Fax

    From: Ben May
    To: 'rp-ml@rapid.lpt.fi'
    Sent: Thursday, August 22, 2002 6:10 AM
    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
    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

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