Design of Experiment and Evaluation of Abrasive Waterjet Cutting in Titanium Alloy Sheet

Abstract

High demands on components in the aerospace industry empower the use of advanced manufacturing processes in order to increase quality and reduce costly processing steps. This includes non-conventional machining such as Abrasive Waterjet where the components are cut through abrasive impingement by means of abrasives accelerated by pressurized water. While avoiding effects of heating in the material, the technique entails some considerable characteristics. Thus this master thesis aims to analyze the process and experimentally study the effect of selected process parameters. Titanium alloy sheet samples of different thicknesses were cut by abrasive waterjet while varying cutting speed, water pressure, abrasive feed and grit size with both a standard technique and a finer micromachining technique. Sections of the samples were prepared by polishing followed by etching and then analyzed through visual inspection, optical and scanning electron microscopy and XEDS analysis. The analyses of the samples indicated varying extent of known characteristics and through statistical analysis their relations to process parameters could be assessed. Main factors of the abrasive waterjet process were found to be the material thickness and cutting speed, influencing all responses to some extent. Through the design of experiments approach it was found that some responses could be correlated to models with significance, while other correlations lacked significance due to difficulties in measurements or other error sources. Grit embedment in the kerf was confirmed which might conflict present specifications on contamination. Yet, the consequence and distribution of grit particles needs to be considered.