Re-usable mould to cast ally parts.

[Me.Participant @me1]

I'd like to cast some ally parts but want to re-use the mould. What would be the best way to do this. What material would be most suitable to make it from.

I'd like to make 10 items the same.

My thoughts would be to 3D print the part and then make the mould from that.

[Me.Participant @me1]

[noel shelleyParticipant @noelshelley55608]

Depends on the item as to wether this is possible in the home workshop. Better to greensand mold from your 3D printed pattern. A steel mold ! You will be looking at between 650 – 750C for heat – dull red. Noel.

[Nigel Graham 2Participant @nigelgraham2]

I believe there are refractory material boards made for such purposes as insulation in domestic heating boilers, stoves, and the like.

I don't know if it would be possible to use this material, which can be cut and drilled though probably not to greater accuracy than you'd achieve with sand.

It's probably not very readily available either – you may need ask a GasSafe or HEATAS accredited plumbing firm rather than search the Screwfix catalogue.

[PatJParticipant @patj87806]

There is a fellow on ytube called Olfoundryman, and he die-casts aluminum using I think a steel mold.

He says you have to spray on a special ceramic coating onto the mold, else the aluminum will stick.

You could cast a permanent mold in gray iron, but that would be a rather tedious thing to do.

The standard reusable mold material is greensand or perhaps oil-based sand (Petrobond).

Aluminum typically pours at 1,350 F, or 732.2 C.

Temperatures in excess of this will give a poor surface finish on aluminum.

 

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Edited By PatJ on 30/09/2022 22:22:01

[Ramon WilsonParticipant @ramonwilson3]

When I was making parts for the Bentley rotary engine there was a need to cast the manifold elbows in aluminium.

I made a mould from two pieces of EN1a steel located by taper dowels and machined each side separately to tight tolerances to ensure alignment

I proved the mould by using lead and smoking the surfaces with a candle

Though I carried out the above fairly early on in the making it was not used 'in anger' for many years until I loaned it to someone who was also building the same engine.

He not only successfully cast sufficient elbows for himself from it but enough for my project too

As you can see the mould was quite heat stressed but unaffected by the twenty plus parts.

I have an idea that the OP wants to create a mould from a pattern similar to a silicone mould but though that will take molten lead or white metal I doubt it could withstand the temp of molten aluminium

Might be of help though

Tug

[Neil LickfoldParticipant @neillickfold44316]

Cast Iron is also a good material for Ali casting as well.

For a few parts there is someone 3d printing, then pouring the Ali into the mould, and the ali melts out the plastic as it is poured in. Can't remember the plastic type used. Im sure an internet search will find the process though.

[JasonBModerator @jasonb]

Can you post an image of the part as if you need an open single part mould or two part will also affect how the mould could be made.

If the shape of the item can be pulled fairly easily when you take a mould of it you could consider using an investment powder to form an open mould but would really be single use.

ay simply be easier to print 10 parts for lost PLA or similar rather than making and proving a mould.

[noel shelleyParticipant @noelshelley55608]

As Tug has shown, a steel mold will work ! BUT the time spent making the mold and also the fact that it should have been cored, therefore the extra time in boring out the casting. Sand molding would have been quicker and easier and since using 3D printing one could make a double pattern or even more off one gating system and save even more time. Noel.

[Ramon WilsonParticipant @ramonwilson3]

Hi Noel, Hope you are well.

Spoken like a fine foundry man

I did consider a core but at the time the extra work to the mould to hold such far outweighed the extra work to bore the castings from each side whilst the respective faces where being machined.

I offered the above purely as an example of what I did and the end result achieved – certainly not the only way to approach this

Theres an awful lot of cats in this one for sure.

Best – Tug

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