> Does anybody have any experience of investment casting using 3D Systems
> Actua models, in particular no. and type of shell coats & burnout times. My
> understanding is that the models behave pretty much like wax patterns, but
> any I would be interested to learn of any potantial probelms that anyone is
> aware of.
we often build actua parts for investment casting rather than Quickcast parts - particularly when we are in a hurry and/or the down facing surfaces are not critical or are easy to post process. Yes they seem to behave just like injected waxes, maybe even a bit better since they are not as dense and therefore put less stress on the shell during burnout.
Pattern PostProcess: 1 hour 1 Day
Shell Building: 1 Day (6-7 coats) 2 Days (up to 10)
Burnout&fire: 40mins 1.5-2 hour
(incl. casting): 2 Days 4 Days
(For burnout we use a Flash Fire furnace)
As for accuracy, well we've been very impressed by the actua, with careful calibration its almost as good as the Quickcast. But as Mike Maguire said in a recent post, the pattern inaccuracies are generally insignificant compared to the casting distortions. Also the stress on the shell during burnout seems to play a big part in the final dimensions. We have benchmarked waxes, SL, SLS, FDM, LOM for investment casting - some of the waxes (including wax FDMs) were the most inaccurate patterns yet produced the most accurate castings! I can email you these results if you wish.
-- Tony Riek, Rapid Prototyping and Tooling Team, Telephone: +61 7 3364 0736 Queensland Manufacturing Institute, Facsimile: +61 7 3364 0786 P.O. Box 4012, Eight Mile Plains, QLD 4113. Internet: email@example.com
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