Micro Abrasive Water Jets Machining Equipment Design And Processing

The hard brittle materials such as glass, silicon wafer and ceramics etc. are basic materials for electronic components and optical components. Demand for the processing of such materials with high hardness, high brittleness, high melting point just increases continuously.Micro Abrasive Water Jet (MAWJ) is a new micro processing technique developed based on the fundamental of traditional Abrasive Water Jet (AWJ), it doesn't change the mechanical, physical and chemical performance of the material. Now MAWJ has become a basal technology for micro processing of hard and brittle materials.A new MAWJ machining equipment and the research of the machining process for brittle materials are presented in this thesis. Detailed experiments are carried out to analyze the influence of the process parameters such as jet pressure, impacting time, impacting angle and abrasive concentration on the mass loss, depth and diameter of the hole, finally the similarities and differences of the MAWJ and AWJ are analyzed. The major results are as follows:(1) The diameter of nozzle of the MAWJ can be change from 0 to 0.25mm, working pressure can change from 0 to 35MPa, and the device can be used for cutting, drilling and polishing diffirent kinds of materials.(2) The glass with thickness of 2.5mm can be drilled through when the jet pressure reaches 1MPa, and the stainless steel with thickness of 0.6mm can be cut through when the jet pressure reaches 5MPa.(3) Furthermore, a new method to improve the machining precision that machining workpiece under a cladding material is discussed.(4) The experiment of drilling glass shows that the mass loss of wordpiece increases with the growth of jet pressure, impacting time and abrasive concentration, contrary with stand off distance. The most remarkable influence factor on mass loss and the depth of the hole is impacting time, the most remarkable influence factors on the diameter of the hole is impacting time and jet pressure. The impacting time is the most important factor for drilling brittle materials. The results shows that the drilling hole is more fine and deep with low jet pressure, abrasive concentration, small stand off distance and impacting angle of 90 degree. To decrease the stand off distance and increase the impacting time is an effective manner to increase the mass loss. (5) The experiment of cutting steel plate with AWJ shows that the most remarkable influence factor on top kerf width and kerf taper angle is stand off distance, the most remarkable influence factor on the smooth depth of cut is cutting speed. The top kerf width can be reduce by reducing the stand off distance, while reducing cutting speed can increase the smooth depth of cut and reduce the kert taper angle.(6) Comparing with MAWJ and AWJ, the impact time and abrasive concentration have the same infection on machining capability and fineness, impact pressure and stand off distance in reverse. The structure of MAWJ nozzle should be improved base on the structure of AWJ nozzle to satisfy the performance and life demands for MAWJ. MAWJ's processing precision is higher, while efficiency is lower.