Ultrahigh-Pressure Cryogenic Jet Cutting of Steel

This project will advance the state of the art of ultrahigh-pressure (UHP) jet machining technology. Existing technology uses water as the working fluid that accelerates abrasive particles in high-velocity, highly coherent jets. Despite successful demonstration and industrial utilization of the technology in cutting, cleaning, drilling, turning, milling, and surface-preparation operations, it remains poorly suited to important applications in which environmental considerations (safety, cleanliness, waste management) prohibit the use of liquid water. For such situations, liquefied gases are emerging as attractive alternatives to water as the UHP jet working fluid. In Phase I, the feasibility of obtaining cryogenic UHP jets of liquid nitrogen (LN2) will be demonstrated, and their cutting performance will be investigated. An in-house cryogenic pump will be used to pressurize the LN2 up to 150 MPa (22 ksi). This phase of the project will explore the thermodynamic conditioning of the UHP cryogen necessary to achieve jets with cutting power; optimal nozzle materials and geometries; and hardware requirements for addition of abrasive particles to the cryogenic jet. It is anticipated that the proposed work will verify the feasibility of incorporating cryogenic liquids into UHP jet technology. Exploratory tests will also be performed to entrain abrasives into the LN2 jet. Based on these data, conceptual design of a prototype system will be prepared for fabrication and testing in Phase II.