Rapid Freeze Prototyping

Rapid freeze prototyping (RFP) is a relatively new solid freeform manufacturing process that builds a three-dimensional part according to the CAD model by depositing and freezing water droplets layer by layer.

Rapid freeze prototyping is a solid freeform manufacturing (SFF) method that uses ice water as its medium. The system consists of a pressurized water container unit, an X-Y table for manipulating the plate to obtain the correct geometry of the component, a Z-axis elevator for raising the nozzle for successive layers, a circuit- driven nozzle, and a freezer. Figure 3.15 shows the schematic of the configuration. The nozzle is a precision micro-dispensing drop-on-demand nozzle that is cyclically opened by a function generator. The nozzle is supplied with water through a Teflon tube. Once the water leaves the Teflon tube, it enters the nozzle where it encounters stainless steel, polyphenylene sulfide, polyetherketone, ethylene/propylene rubber, butyl, epoxy, and finally sapphire before it is released to the substrate below. The materials with which the water comes into contact are critical because, if the water sticks to these materials, the flow rate would be greatly reduced due to adhesion. Materials that comprise the feed tube and the nozzle are materials that the water flows through with minimal adhesion.

There are many advantages to using rapid freeze prototyping over other SFF techniques, including stereolithography, fused deposition modeling, selective laser sintering, laminated object manufacturing, three-dimensional printing, and direct material deposition. Many SFF techniques use various materials in their methods, including UV curable resin, wax, ABS, metal/ceramic/polymer powders, and adhesive coated papers. As RFP uses water as a working material, the working environment is much

FIGURE 3.15 Principle of rapid freeze prototyping.

cleaner than alternative SFF techniques. Water is also easily available and inexpensive to use. RFP also provides quick construction time, less energy usage, clean and simple substrate detachment, and a very good surface finish.

3.9 FDM 3D PRINTING FOR ZYGOMATIC