Liquid carbon dioxide jets for cutting applications

In this work, the applicability of high pressure carbon dioxide jets for cutting applications was investigated. For the cutting process, carbon dioxide is compressed to up to 1600 bar and expanded via a sapphire nozzle. A pressure chamber is installed downstream the orifice to keep the post-expansion conditions above the triple-point pressure of carbon dioxide. To use the advantages of a thermodynamically stable, liquid cutting jet, carbon dioxide has to be expanded to an environment of increased pressure. By applying this procedure, single-phase ‘liquid’ or two-phase ‘liquid/gaseous’ jets can be generated. We show that it is generally possible to cut different materials with these jets. While a carbon dioxide jet does not show any effect on different material samples under atmospheric pressure, the impact increases dramatically using an elevated pressure downstream the nozzle. Different materials, such as wood, aluminium, and polycarbonate could be perforated with liquid CO2. It could be observed that the pre-expansion pressure shows a significant influence on the cutting results. The impact of the jet can be improved by increasing the liquid fraction, for example. Furthermore, the observations suggest that a carbon dioxide jet allows to process materials more precisely and more gently than a high pressure water jet does.