Machining characteristics of abrasive jet machining

Abstract

This paper describes the performance of the high-pressure abrasive jet machining (AJM) system and the relationship between injection and machining characteristics on drilling of quartz workpiece. AJM process is similar to the sand blasting, and effectively removes hard and brittle materials such as glass and ceramics. AJM uses fine abrasive powders and small nozzles whose inner diameter (ID) is below 1 mm. As the abrasive jet stream from the nozzle is focused onto the workpiece, small holes or slots can be machined easily. Impact velocity Vp0 (velocity of abrasive before collision) and density of impacting abrasives n (frequency of impacting abrasives per unit area) are measured through a laser Doppler anemometer. Results are as follows: (1) Impact velocity Vp0 is proportional to the 0.23 power of carrier gas pressure Pc, in the mixing chamber of the AJM unit. (2) The density of impacting abrasives n is constant and independent of Pc in a large ID nozzle. In a small ID nozzle, the value of n decreases in smaller Pc. (3) As the gap between nozzle and workpiece increases, the value of Vp0 increases and the n decreases. (4) The larger value of Pc and the smaller supply of abrasives are, the straighter hole can be drilled. (5) Stock removal rate is proportional to the 3.7 power of impact velocity in this experimental condition.