Rapid Freeze Prototyping and Manufacturing



 

Investigators:

Ming Leu (mleu@mst.edu, 573-341-4482), Von Richards, Robert Landers, Gary Bertrand, Qingbin Liu, Francie Bryant, Mike Mason, Joel Lamson

Funding Source:National Science Foundation, Department of Education, Tel Med Technologies, University of Missouri Research Foundation
Project Description:

This project is aimed at developing a novel solid freeform fabrication process, called Rapid Freeze Prototyping, and developing a new investment casting process using the fabricated ice patterns to produce metal castings. Rapid Freeze Prototyping builds ice parts from CAD models by selectively depositing freezing droplets of water in a layer-by-layer fashion. Compared with other SFF processes, it has many advantages including cheaper equipment and material, cleaner material and process, less energy consumption, faster building speed and better surface finish. We have studied the technical feasibility of this rapid prototyping process and its investment casting application. We have investigated issues including part and support materials, geometric coverage, dimensional accuracy, and surface finish. We are developing on-line process control strategies that adjust the process parameters to regulate the part morphology. The goal is to develop an enabling technology capable of building three-dimensional ice parts of any three-dimensional geometry accurate enough for making metal castings used in industrial and medical applications.

Web link for this project: http://web.mst.edu/~vrpl/proj-rp.htm

Publications:

1. “Rapid Freezing Prototyping with Water,¿? W. Zhang, M. C. Leu, Z. Ji, and Y. Yan, Journal of Materials and Design, Vol. 20, June 1999, pp. 139-145.

Abstract: Rapid Freezing Prototyping (RFP) with water is a novel solid freeform fabrication technique that can generate three-dimensional ice objects by depositing and rapidly freezing water layer by layer. It provides a means to build a solid (ice) part with the potential of better performance than other solid freeform fabrication techniques in many aspects. The support, where necessary, is made of material whose freezing point is lower than pure water. After building the part, the support can be removed by utilizing the melting temperature difference between water and the support material. Preliminary experiments have shown that the ice patterns can be used for design visualization and silicone molding. This paper presents the concept and some experimental results of the RFP process as well as its potential applications.

2. “An Experimental and Analytical Study of Ice Part Fabrication with Rapid Freeze Prototyping,¿? M. C. Leu, W. Zhang, and G. Sui, Annals of the CIRP, Vol. 49, No. 1, 2000, pp. 147-150.

Abstract: This paper presents the results of study on a novel, environmentally conscious solid freeform fabrication process called Rapid Freeze Prototyping. This process builds a three-dimensional ice part by depositing and rapidly freezing water according to its CAD model in a layer-by-layer manner. It provides a means to build a solid part with the potential of better performance than other rapid prototyping processes, including use of cheap and clean material, potential to build accurate ice parts with excellent surface finish, and ease of building color and transparent parts. An experimental system with a low-temperature building environment, a three-axis positioning mechanism, a water feeding and extruding subsystem, and control hardware and software has been built. Experiments conducted on this system demonstrate the feasibility of making three-dimensional ice parts. A heat transfer analysis helps understand the freezing process and provides useful information to the selection of building parameters.

3. “Study of Part Geometric Features and Support Materials in Rapid Freeze Prototyping,¿? M. C. Leu, Q. Liu and F. D. Bryant, Annals of the CIRP, Vol. 52, No. 1, 2003, pp. 185-188.

Abstract: This paper describes the investigation of part geometric features and support materials in the fabrication of ice parts by Rapid Freeze Prototyping (RFP). The achievable geometric features of the ice part including the smallest thickness of a wall and the smallest diameter of a rod are analyzed and expressed as functions of process parameters including water pressure, nozzle diameter, valve open/close frequency and duty cycle, and x-y table moving speed relative to the nozzle. The validity of the predicted results of geometric features from the analysis is verified using our experimental RFP system. In order to realize fabricating ice parts of any complex 3-D geometry, support materials are also studied. The experimental results showed a eutectic mixture of dextrose and water works well as the support material while a eutectic mixture of salt and water does not work satisfactorily.

4. "Thermal Analysis of Ice Wall Built by Rapid Freeze Prototyping," G. Sui and M. C. Leu, ASME Journal of Manufacturing Science and Engineering, Vol. 125, No. 4, November 2003, pp. 824-834.

Abstract: Rapid Freeze Prototyping builds ice parts by depositing and freezing water in a layer-by-layer manner. This paper presents a one-dimensional transient heat transfer model for a thin ice wall built by this process. Closed-form solutions for temperatures of the ice wall during solidification of a layer of water are derived, which can be used to estimate the solidification time. Natural cooling of the ice wall after solidification of a water layer is also studied. The analytical solutions of heating and cooling of the ice wall agree well with both numerical and experimental results.