Plastic material for making casting patterns

[Stewart HartParticipant @stewarthart90345]

Hi all

I've seen some ware a plastic for making casting patterns on CNC machines, does any one know what this material is called and where you can purchase it from.

Thanks

Stew

[Stewart HartParticipant @stewarthart90345]

[Brian OldfordParticipant @brianoldford70365]

Are you thinking of Sikablock? It's available from the likes of http://www.johnburn.co.uk/

I use it from time to time in my professional capacity.

[Stewart HartParticipant @stewarthart90345]

Bloody hell that was a quick reply.

That,s the stuff.

Thanks Brian

Stew

[Neil WyattModerator @neilwyatt]

Hello Stew, I think they use polystyrene and polyurethane foam in industry.

Neil

[Brian OldfordParticipant @brianoldford70365]

Polystyrene is frequently used as a sacrificial pattern material. Useful for large-ish one-offs. OK for CI but other processes need to be added if casting steel or other materials where the carbon content must be controlled.

Sikablock (and similar from other vendors) is just such a polyurethane material. It's available in a huge range of densities. The lightest has similar mechanical properties to Oasis that used by flower arrangers. The densest could be used to drive nails in with.

[Sam StonesParticipant @samstones42903]

Stewart,

To add a little more to this thread –

Polystyrene – actually expanded polystyrene (or EPS) is a foamed thermos-plastic, which will melt when heat is applied. It is often used as a form similar to the lost wax or investment casting process, melting and burning off as molten metal is poured into the mould.

Polyurethane is generally a thermo-setting plastic, which therefore doesn’t melt when heated.

Try **LINK**

Sam

[David BrandonParticipant @davidbrandon24162]

I use polyurethane foam for most of my patterns. I use 50 lb per cubic ft. Most signs are now carved from this stuff using 15 lb/ft

Dave

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