Research On Mechanism And Application Of Abrasive Jet Machining

Abrasive jet machining(in brief, AJM) is a kind of special machining method in which gaseity-solid mixture is formed by mingling high-pressure air or other gas with abrasives. Applied by specially-designed nozzle, these particles impact and erode workpiece so as to remove materials. As the development of modem machining technology, AJM is widely used for surface-treatment and micro-machining, especially for micro- parts of an apparatus made of hard and brittle materials such as glasses, ceramics and single-silicon.Firstly, the process of AJM is analysed. Optical microscopy has indicated that abrasive particles used in AJM have sharp edges with shape similar to cone or pyramid. Moreover, microscopic examination of cross section of work sample eroded by AJM shows that, for brittle materials, material removal is due to intersection and propagation of cracks produced by adjacent impacting particles on target surface. Based on these phenomena, this dissertation proposed that in brittle material, a crack develops on an impact and many such cracks further aggregated by the following impacts intersect each other, resulting in material removal. Circumstance of acting force of a single abrasive particle is analysed and an analytical model has been developed based on this.Experiments are carried to analyse the process of AJM using lab equipments and a device designed by author. Factors affecting AJM such as mass flow rate, velocity of abrasive particles are being fully discussed and the model is verified based on experiment data. All these provide a clear picture of the mechanism of AJM and found a base of its future application.