Generation of liquid CO2 jets under atmospheric conditions for cutting applications

As an addition to conventional manufacturing methods, CO 2 jet cutting represents a promising option to process materials. The use of liquid carbon dioxide enables residue-free and dry processing, as it evaporates after the procedure. In CO 2 jet cutting, the medium is compressed to some hundred MPa before expanding through a nozzle to atmospheric conditions. With a triple point pressure of 0.518 MPa, carbon dioxide should not exist as liquid after expansion, if in thermodynamic equilibrium. However, under specific conditions, liquid jets can be generated, especially with nozzle diameters smaller than 0.1 mm. After a few centimeters of coherent liquid jet, phase transition occurs and the jet disintegrates into a spray. So far, it has been possible to generate liquid CO 2 jets that are suitable for cutting soft materials such as polymers. Jet stability, length and cutting properties are significantly affected by pre-expansion pressure and temperature, as well as nozzle diameter. • A novel system for CO 2 jet cutting with a movable cutting head has been developed. • It is possible to generate liquid carbon dioxide jets at atmospheric pressure. • Low fluid temperatures and high pressures favor the generation of liquid jets. • The cutting depth of the liquid CO 2 jets decreases with reduced nozzle diameters. • Finer cutting kerfs can be produced with smaller nozzle diameters.