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Requesting Suggestions for Investment Casting Prototypes

Question asked by Dennis Dohogne on Mar 19, 2019

I need to find a good way to rapidly prototype investment castings.  This means finding a way to quickly and affordably make multiple (10-20) wax masters.  I have looked into wax 3D printers and have found some that do an amazing job, but either they are for jewelry and dental work, which is far too small for our parts, or they take a long time and are expensive.  Our parts are typically 2" x 2" x 6".  I had a sample printed on a high-end machine and the result was beautiful, far smoother than I expected.  The machine is over $100k so we are not interested in making that kind of purchase.  Also, it took 45 hours just to print the one part.  Though printing two or three at a time would not be multiples of the 45 hours, it would still take a lot longer.  As a further complication of the part, the geometry is such that it requires core pulls for molding the master.

 

So now I am considering two options and seek the advice of anyone that has done them.

Option 1.  3D print the part master and make a silicone mold(s) from it for the wax.

Option 2.  3D print the mold itself, including the core pulls.

In both options we would likely use a high resolution SLA for the 3D printing.

 

Option 1 concerns me due to the typical flexing of the silicone mold, that we might break the wax in removing it.

Option 2 concerns me about the wax releasing from the SLA mold.  Perhaps it is easily solved with an appropriate mold release coating.

 

If you have direct experience with this type of situation I would really appreciate your help/suggestions.

 

Edit:  I forgot to add that we have evaluated the SLA materials that burn out, but for the size of our parts and the thicknesses it does not burn out cleanly enough.

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