9312980 Gordon The overall goal of the research is to develop a practical shaping and grinding technology based on the use of a high speed water ice microparticle mixture (icejet). The acquired knowledge will be used for equipment design, selection of operational conditions, and demonstration of the capability of the technology. Preliminary experiments have yielded some ice in a high velocity water stream. The main technical uncertainty in the work is the ratio of ice to water that can be achieved in practical implementations. Several approaches will be studied, but one is favored because it will clearly work to at least some extent and is relatively straightforward to implement. The desired technology may include the following, individually or in combination: (1) The use of cooled water as it enters the nozzle; decompression and mixing of the water as it emerges, putting it into a turbulent, supercooled state which will produce ice on a microsecond time scale. (2) Use of liquid CO2 or other low temperature fluid as part of the stream to achieve further cooling during decompression. (3) Entrainment of ice particles in the stream as in conventional abrasive waterjet. (4) Injection of a waterjet (WJ) into a water ice layer. A second area of uncertainty involves the effectiveness of ice particle as an abrasive medium. A practical procedure for icejet formation will be developed and the interaction of the resulting jet with various engineering materials will be investigated. The experiments will be conducted under a wide variety of process variables (pressure, temperature, flow rate) and various designs of the nozzle and mixing chamber. The temperature change a nd size of generated particles will be closely monitored. Parameters for IJ machining will be established and the range of practical use of IJ machining will be identified. The end result of the study will be a design for a pilot plant for IJ machining. It is anticipated that the developed IJ will combine the positive features of a laser (the high material removal rate, ability to remove a wide variety of engineering materials, and small beam diameter when desired) and a WJ (cleanliness, high continuous power, a wide range of flow cross section areas, simplicity of the process control, minimal heating, and limited damage area). Such combination of features will enable development of an effective, flexible tool for material shaping, grinding and cleaning. The expected use of IJ includes such fields as high productivity drilling of small diameter holes (<5 mils) in multilayer circuit boards, food processing, precision grinding of very large metal and glass surfaces, and bioengineering/medical applications. Success in this endeavor will result in an effective and productive alternative to laser and waterjet machining that would be useful for cleaning and polishing hard materials and for high speed cutting of food and live tissue.
