Dear list,
The basic idea of Rapid Freeze Prototyping (RFP) is using water to build ice prototypes. I am a PhD student working on RFP from the very beginning (1998) of the project, previously in New Jersey Institute of Technology. According to my experience in RP field, there are three advantages of RFP:
1.. Surface quality. I just updated an introductory web at http://www.umr.edu/~vrpl/rfp.htm. I added some new pictures of ice patterns we made recently. Actually you can hardly see the stair-stepping effect. This is not possible if the contact angle between water and ice is not small. Yet we have no quantitative number now.
2.. Colorful parts.
3.. Faster building speed. This is due to the low viscosity of water. We can flush lots of water into a fast built ice shell. Even if we pour 20mm (200 layers if the layer thickness is 0.1mm) 0C water into an ice shell, the shell won’t collapse! Please look at http://131.151.113.65/sui/buildingcon1.jpg and http://131.151.113.65/sui/buildingc2.jpg for a more detailed explanation.
4.. Rapid tooling. Investment casting with ice patterns achieved very good result.
The most challenging problem now is the suitable support material. The considerations of support materials include melting point, solubility, wettability, and thermal conductivity. We came up with a lot of ideas like dry ice, alcohol. But it seems no one works now. Vegetable oil seems to be a good choice if we use print-heat instead of valves to build ice parts. Oil becomes harder at lower temperature and it is easy to be separated from ice part. The problem is its conductivity is not good. Thus it limits the building speed, which is dominated by heat transfer.
Merry Christmas to you and your family!
Guanghua Sui
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ME Department, University of Missouri – Rolla
573-341-6815
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