Parametric Effects on Particle Deposition in Abrasive Waterjet Surface Treatments

Abstract

The abrasive waterjet (AWJ) has primarily been used for net-shape sectioning of engineering materials. In this study an AWJ was adopted for the surface treatment of commercially pure titanium (cpTi) and the contribution of treatment parameters to material removal and the deposition of particles within the substrate were examined. The surface texture and material removal rate were analyzed using conventional techniques whereas the quantity of abrasive particles embedded within the cpTi surfaces was determined using energy dispersive X-ray analysis (EDXA). Parametric effects related to particle hardness were distinguished from a comparison of surfaces treated with Aluminum oxide, garnet, and crushed glass abrasives. According to an analysis of variance (ANOVA), treatment responses were found to be primarily dependent on the abrasive size, abrasive hardness, angle of incidence, and jet pressure. The minimum and maximum concentration of particles embedded in the AWJ treated cpTi (in percent surface area covered) was 2.5 and 21.6%, respectively. Particle concentration and mean particle size in the cpTi increased with abrasive size, angle of incidence and jet pressure; the particle concentration reached saturation at an angle of incidence near 80 . Although abrasive hardness was important to the ORDER REPRINTS treatment responses, an increase in hardness beyond 800 on the Rosiwal scale resulted in minimal changes in material removal or other features of the process.

An in vitro investigation of the effect and retention of bioactive glass air-abrasive on sound and carious dentine

“…Similar findings were noted in studies looking at abrasive retention on metal surfaces 11 and were attributed to the more brittle nature of the glasses examined, causing the particle to fracture rather than embed in the substrate. The nature of dentine is very different to that of metals however and the reason for the results seen here might not be the same.…”

Abrasive waterjet cutting of a titanium alloy: The influence of abrasive morphology and mechanical properties on workpiece grit embedment and cut quality

“…Since there was no iron in the titanium alloy substrate, the iron signal from these surfaces could be attributed entirely to the presence of garnet grit. As suggested by Arola and Hall (2004), the area percentage of grit was determined as the ratio of the proportion of iron in the cut surface and the proportion of iron in the garnet particles which had been employed to process the material. It is important to note that the accuracy of EDX analysis is related to the roughness of the surface being analysed (EDX analysis should be used on a polished surface for highest accuracy); thus, accuracy will be reduced on analysis of the rough as-cut surfaces, particularly in the case of the specimens cut at the higher jet-traverse speed where the roughness was higher.…”

“…It was found that both the amount of residual grit and the penetration depth of the sub-surface embedded grit increased with increasing grit size. In milling of surfaces with AWJ (as opposed to throughcutting), a number of workers, including Fowler et al (2005), Arola and Hall (2004) and Shipway et al (2005) have shown that grit embedment increased with increasing impact angle (defined as the smallest angle between the jet axis and a vector lying in the plane of the surface onto which the jet is impinging) due to the higher impulse during impact as the impingement angle was raised. They also demonstrated that the grit embedment was controlled by both abrasive particle size and its impact velocity.…”

“…They demonstrated that up to 40% of the area of a milled surface consisted of embedded abrasive. Arola and Hall (2004) used AWJ for the surface treatment of commercially pure titanium (cpTi) and examined the embedment of grit as a function of process variables, including size and type of abrasive. Embedment area fractions of up to 21% were observed.…”