A Study On Precision Abrasive Airjet Polishing Technology

Abrasive Airjet Machining has many advantages, such as high machining versatility, almost no heat generated and low machining cost. So it is a very ideal technology to machine hard-brittle materials. However, there is a few of study on precision polishing technology of Abrasive Airjet Machining. Therefore, in this thesis, the polishing performance and the erosion mechanisms of Abrasive Airjet Machining is investigated on polishing quartz and KDP. This research will provid an effective precision machining technology for hard-brittle materials, and promot the application of Abrasive Jet Machining in industrial.The effect of various process variables on the surface roughness are studied by experiments. The results show that the polished quartz surface roughness first decreases with an increase in airjet pressure, and then increases. And the polished quartz surface roughness increases with an increase in nozzle traverse speed and incidence angle, and first increases with an increase in standoff distance and abrasive flow rate, and then decreases. The polished surface morphology quality of quartz is becoming firstly better with an increase in airjet pressure and then becoming worse, and also is becoming better with an decrease in nozzle traverse speed, standoff distance, abrasive flow rate and incidence angle. The predictive models for surface roughness related to various process variables are constructed.The polishing performance of quartz and KDP with Abrasive Airjet Machining is studied by experiments. It is shown that the effect order of process variables on the polished quartz surface roughness is airjet pressure, incidence angle, standoff distance, abrasive flow rate, and the nozzle traverse speed. The effect order of process variables on the polished KDP surface roughness is standoff distance, airjet pressure and the nozzle traverse speed. The most superior experimental combination in chosing process parameters is obtained, and the predictive models for the polished quartz and KDP surface roughness are established by regression analysis. The erosion mechanisms of Abrasive Airjet Machining is investigated, and effective erosion kinetic energy models of single abrasive particle in fracture erosion and ductile erosion is analyzed. If the erosion kinetic energy is reduced, the erosion is formed in the ductile erosion mechanism and the good surface quality can be obtained.A study on the erosion mechanisms of Abrasive Airjet Polishing for hard-brittle quartz is conducted. It is shown that brittle-ductile transition mechanisms of polishing quartz materials with Abrasive Airjet do exist. Under lower erosion kinetic energy conditions, the ductile erosion occurs without scratch damage in material.. So the precision Abrasive Airjet polishing technology is a promising technique on machining hard-brittle materials.The mathematical model for the surface roughness polished with Abrasive Airjet for one single-pass is established. The polished profile of a single-pass polishing of the jet can be built as a form of zigzag. Therefore, the surface roughness model is established using the ductile erosion mechanism and verified experimentally.