Surface evolution models for abrasive slurry jet micro-machining of channels and holes in glass

Abrasive slurry jet micro-machining (ASJM) uses a jet of abrasive slurry to erode features with relatively high resolution without the need for a patterned mask. The present study investigated the ability of a surface evolution model to predict the profiles of micro-channels and holes machined in borosilicate glass with a newly developed ASJM system. The system could produce micro-channels with depth and width variations along their length of less than 3%, and a channel-to-channel repeatability within 5%. The fundamental erosion rate of the borosilicate glass was measured as a function of impact angle using a slurry of water mixed with a low concentration of 10 and 25 µm nominal diameter aluminum oxide particles. This erosion rate-impact angle relationship was used in an existing model developed previously for the abrasive air jet micro-machining of brittle materials. The results demonstrated that, despite the differences in abrasive flow patterns between air and slurry based systems, the surface evolution model accurately predicted the profiles of micro-channels with a maximum error of 7% for aspect ratios (depth/width) of up to 5. The predicted profiles of holes were also in reasonable agreement with a maximum error of 14% for aspect ratios close to 1.