Study Of Tool Wear In Micro Machining Of Ceramic Compacts

Ceramics has many excellent properties, such as high strength, high hardness, and resistance to corrosion, wear and high temperature. With the development of MEMS, the demand of micro parts is increasing and ceramics is attracting the attention of industries. The sintered ceramic compact is difficult to be machined using traditional machining methods because of its high strength and hardness. The method used widely is non-traditional manufacturing process such as EDM, USM, laser machining. The accuracy of rapid prototyping technology is low. However, the process is complex and the equipment is expensive. The low strength of green ceramic body is makes it easy to be machined. The quality of machined micro structure is low. Therefore, it is necessary to find a suitable method to improve the quality of machining results of ceramic materials.In this paper, the generation of micro structures was achieved through micro machining pre-sintered ceramic materials. The pre-sintered ceramic compact is sintered below the final sintered temperature, which has an appropriate strength suitable for micro machining.The micro machining tools were prepared using the technology of wire electrode discharge grinding. The machining program was developed. Combining with the rotation of the spindle and the feed movement, the micro tools with different cross sections such as semicircle, triangle, square, etc. were produced. The micro ceramic structures were able to be machined based on the vertical machining tool and the control program.The tool wear influences on the process of machining and the quality of the micro structure seriously. It is very important to study the phenomenon and value of the tool wear. Therefore a series of micro cavities were machined on the pre-sintered ceramic compacts. The tool wear was studied under the conditions of different processing parameters including the cross section of the micro tool, the strength of the pre-sintered compact, the milling thickness of layer, the rotation speed, the cutting speed, etc. According to the experimental results of the axial and radial wear of the micro tools and the quality of the micro cavity, the most suitable machining parameters were selected for the micro machining. The optimized machining parameters were used to machine three different sizes of the micro cavities. The machining gap and tool wear were measured. The machining gap is the gap between the micro tool and the wall of the cavity. The tool wear mainly refers to the axial wear. The tool wear was measured by the relative volume attrition rate. The machining gap and the tool wear were calculated under the condition. The micro cavities were compensated mainly through changing the size of the machining structures. The sizes of the micro cavities after compensating were measured and they were very close to the target sizes. The result showed that the compensation method was feasible.