Design oriented simulation for plasma arc cutting consumables and experimental validation of results

Abstract

Electrode and nozzle erosion mechanisms in plasma arc cutting processes of mild steel have been studied while designing a prototype mono-gas plasma torch, operating in the range 25–160 A. The correlation between the distribution of different quantities inside the plasma chamber and the erosion mechanisms of the hafnium emitter surface and of the nozzle inner surfaces have been investigated by means of a 2D ANSYS FLUENT-based numerical model, with the final aim of optimizing the overall performances of the prototype. Modelling and numerical simulation have allowed better understanding of the physical phenomena evidenced by experimental results and have suggested successful design solutions for consumables (in particular nozzle, electrode and primary gas diffusers). The correlation between the results of experimental tests and numerical simulations has proven useful in overcoming the critical aspects initially pointed out, significantly improving the expected lifetime of consumables. Results have been analyzed with respect to plasma behaviour, and conclusions have been drawn, concerning the powerfulness of numerical simulation as a tool for designing plasma cutting torches.