Rapid freeze prototyping

Presentation on Rapid Freeze Prototyping

Submitted by –Sandeep Kashyap

M.Tech. (Prod. Engg.)2015PR21

Submitted to –Dr. Praveen Kumar AgarwalMechanical Engg. Deptt.MNNIT Allahabad

Overview Rapid Freeze Prototyping IntroductionProcessPotential ApplicationsAdvantages and Disadvantages

RAPID FREEZE PROTOTYPING

Introduction : Most of the existing rapid prototyping processes are still quite

expensive and many of them generate substances such as smoke, dust, hazardous chemicals, etc., which are harmful to human health and the environment.

Dr. Ming Leu of the University of Missouri-Rolla, Virtual & Rapid Prototyping Lab. is developing a rapid prototyping process that uses cheap and clean materials and can achieve good layer binding strength, fine build resolution, and fast build speed.

They have invented such a process, called Rapid Freeze Prototyping (RFP), that can make three-dimensional ice parts of arbitrary geometry layer-by-layer by freezing of water droplets.

Process : As shown in Figure 1, water is pumped from a reservoir to the

nozzle by a pump and then deposited onto the previous solidified ice surface or the substrate.

The newly deposited material is cooled by both the low temperature environment and the ice surface.

As a result the deposited water freezes rapidly and sticks to the previous layer, forming a new layer of the part. Where necessary, brine is used instead of water to build the support.

The nozzle and the transmission pipe are heated and kept at a temperature just above the freezing point of water so that the material may flow smoothly.

Potential Applications :(1) Part Visualization : Parts can be built for the purpose of

visualization. Example can be seen in Figures 3.

(2) Ice Sculpture Fabrication : One application of rapid freeze prototyping is making ice sculptures for entertainment purposes, while Figure 5 shows the part made by RFP.

(3) Silicon Molding : The experiments on silicone molding have shown that it is feasible to make silicone molds with ice patterns (see Figures 6). The key advantage of using ice patterns instead of plastic or wax patterns is that ice patterns are easier to remove (without pattern expansion).

(4) Investment Casting :For making patterns for the investment casting. Figure 7 shows a metal model made by investment casting using ice patterns from RFP.

Advantages and Disadvantages :

RFP has the following advantages:

(1) Low running cost : Rapid Freeze Prototyping (RFP) process ischeaper and cleaner than all the other rapid prototyping processes. The energy utilization of RFP is low compared with other rapid prototyping processes such as laser stereolithography or selective laser sintering.

(2) Good accuracy : RFP can build accurate ice parts with excellent surface finish. It is easy to remove the RFP made ice part in a mold making process, by simply heating the mold to melt the ice part.

(3) Good building speed : The build speed of RFP can be significantly faster than other rapid prototyping processes, because a part can be built by first depositing water droplets to generate the part boundary and then filling in the enclosed interior with a water stream (see Figure 8). This is possible due to the low viscosity of water. It is easy to build colour and transparent parts with the RFP process.

On the other hand, RFP has also the following disadvantages:

(1) Requires a cold environment : The prototype of RFP is made of ice and hence it cannot maintain its original shape and form in room temperature.

(2) Need additional processing : The prototype made with RFP cannot be used directly but have to be subsequently cast into a mold and so on and this increases the production cost and time.

(3) Repeatability : Due to the nature of water, the part built in one run may differ from the next one.

References : Chua C.K., Leong K.F. and Lim C.S., Rapid Prototyping: Principles and Applications 2nd Edition, World Scientific Publishing Co. Pte. Ltd., Singapore, 2003

Wei Zhang, Ming C. Leu, Zhimming Ji, Yongnian Yan. Rapid Freezing Prototyping with Water. (a)Department of Mechanical Engineering, New Jersey Institute of Technology, MEC 204, 200 Central Ave., Newark, NJ 07102, USA (b)Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

Thank You