Micro AWJ Technology for Meso-Micro Machining
Waterjet technology has technological and manufacturing merits that cannot be matched by most established machine tools. There is considerable demand for downsizing beam diameters of abrasive-waterjets (AWJs) to reduce costs for machining of various microproducts. Current production AWJ systems are limited to cutting features around 200 to 300 μm due to difficulties in further downsizing AWJ nozzles. Although waterjets with beam diameters 25 μm or finer have been in use for cutting a limited set of soft materials, it is the AWJ that is difficult to downsize below 200 μm. First of all, the three-phase slurry inside the mixing tube gradually shifts from gravity to capillary dominated flow as the beam diameter of AWJ reduces below 200 μm. In addition, the size of abrasives must reduce accordingly to prevent clogging of miniature mixing tubes resulting from bridging of large particles. The changes in the flow characteristics and flowability of very fine abrasives are most challenging toward nozzle downsizing. Funded by two NSF SBIR grants, OMAX has demonstrated the feasibility of downsizing AWJ nozzles for machining 100 to 50 μm features. Prototypes μAWJ systems are under development. Preliminary results are presented through demonstrating sample parts machined with experimental μAWJ nozzles.