OBSERVATIONS OF TITANIUM SURFACES IMPINGED WITH ULTRA-HIGH PRESSURE WATERJETS

Over the past decades, waterjet processing has become a viable alternative to conventional material removal methods such as chemical milling or grinding. In full, waterjets have exhibited capabilities for cutting, surface texturing, cleaning, material removal, and peening processes – many of which fall into the field of surface preparation. As material advancements continue, research into alternate surface processing methods must strive to keep pace. One material in particular that has experienced an increase in use in the biomedical and aerospace industries is titanium – due largely to its high strength to weight ratio and corrosion resistance. In this study, a waterjet was used to process a titanium alloy at pressures ranging from 275 MPa (40 ksi) to 600 MPa (87 ksi) to characterize the erosion rates based on (i) supply pressure, (ii) traverse rate, and (iii) standoff distance. The erosion rates, resulting surface roughness parameters, and erosion widths were analyzed using optical methods and white light scanning electroscopy. Based on the results of this study, a need exists for a means of minimizing the stochastic nature of the waterjet removal process with respect to erosion width and removal rates. One solution is reducing the traverse rate, but another that has shown promise is the use of the fuzzy waterjet, or water-air jet. Preliminary results for the fuzzy waterjet show that a strong potential exists for uniform material removal at increased processing speeds.