Jet properties and mixing chamber flow in a high-pressure abrasive slurry jet: part I—measurement of jet and chamber conditions

摘要

Techniques to enhance the performance of a high-pressure abrasive slurry jet micro-machining process (HASJM) were investigated by altering the conditions within the jet. The slurry flow rate was controlled using six inlet tubes (cross-sectional areas of 0.2, 0.46, 1.27, 1.77, 3.08, and 4.51?mm_(2)), and was found to have a large effect on the conditions within the mixing chamber. The tubes permitted the use of high-concentration slurry solutions, which resulted in increased machining rates and the ability to machine glass targets without cracking by using a minimum particle concentration of 17?wt%. Slurry tubes producing large slurry flow rates caused the mixing chamber to flood, resulting in a much lower jet velocity. The size of the smallest slurry tube size that caused the mixing chamber to flood was dependent on the pump operating pressure, and varying from 1.27?mm_(2)at 134?MPa, to 1.5?mm_(2)at 233?MPa. Mixing chamber flooding significantly reduced the erosion rate of the jet and increased the machining time, as discussed in the second part of this two-part paper. Mixing chamber pressures were found to be low enough to cause boiling, which increased the jet diameter and the width of features that could be machined without a mask.