Abstract
Abrasive jet micro-machining is a process that utilizes small abrasive particles entrained in a gas stream to erode material, creating micro-features such as channels and holes. Erosion experiments were carried out on aluminum 6061-T6, Ti-6A1-4V alloy, and 316L stainless steel using 50 μm A1₂O₃ abrasive powder launched at an average speed of 106 m/s. The dependence of erosion rate on impact angle was measured and fitted to a semi-empirical model. The erosion data was used in an analytical model to predict the surface evolution of unmasked channels machined with the abrasive jet at normal and oblique incidence, and masked channels at normal incidence. The predictions of the model were in good agreement with the measured profiles for unmasked channels at normal and oblique impact, and masked channels in at normal incidence up to an aspect ratio (channel depth/width) of 1.25. For the first time, it has been demonstrated that the surface evolution of features machined in metals can be predicted.
Highlights
Surface evolution models of Abrasive jet micro-machining (AJM) require as input the erosion rate as a function of the angle of attack, E(α)
Scanning electron micrographs and Energy-dispersive x-ray (EDX) analysis of the eroded surfaces of 316L stainless steel showed a significant amount of particle embedding, with a lesser amount in the Ti6Al-4V alloy (Figure 5-7)
The major findings and contributions of this thesis were as follows: 1. The angular dependence of erosion indicated a ductile erosion response with maximum erosion occurring between 20-35° for aluminum 6061-T6, 316L stainless steel and Ti6Al-4V when eroded with 50μm Al2O33 abrasive
Summary
Conventional micromachining techniques often are limited by material type or present rather costly solutions. The advantages of AJM are its low capital and operating costs, it is an environmentally friendly process that poses no major health hazards, and it has the ability to machine anisotropic and suspended structures on the same substrate [9]. The main objective of this thesis was to develop and test a model capable of predicting the surface morphology of the cross-section of channels machined using AJM in aluminum 6061-T6, 316L stainless steel, and Ti-6Al-4V alloy. This was accomplished by meeting the following secondary objectives: i. Compare the predictions of the surface evolution model to measured cross-sectional profiles from the experiments of (ii)
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