Process repeatability in abrasive jet micro-machining

Abrasive jet micro-machining (AJM) is a useful process for the fabrication of channels and holes in micro-fluidic and microelectronic devices. The small scale of these features and the need to achieve a high degree of accuracy has revealed several problems inherent with traditional abrasive jet equipment. Poor repeatability of the erosion rate in a pressure feed AJM system was traced to uncontrolled variation in the abrasive particle mass flux caused by particle packing and local cavity formation in the reservoir. The introduction of a mixing device within the pressure reservoir ensured that the powder remained loose and able to flow through the orifice to the air stream. This produced a significant improvement in AJM repeatability. Additional factors affecting erosion repeatability such as particle size stratification and the effect of powder level in the reservoir were also examined.