Graphite high-speed machining technology

When developing high-speed machining processes, the following aspects need to be comprehensively considered: (1) cutting parameters; (2) feed method; (3) tool geometry; (4) number of cutting edges and tool shank overhang; (5) cooling conditions; (6) clamping method of the tool shank and machine tool; (7) clamping method of the cutting insert, etc. Currently, scholars in Japan and Germany have conducted some related research on the optimization of cutting parameters and tool geometry angles for high-speed milling and turning of graphite with large diameter milling cutters (≯12 mm). The research results show that: (1) in terms of tool wear, increasing the cutting speed reduces the wear area; increasing the feed per tooth of the milling cutter increases tool wear; increasing the tool rake angle decreases the depth of the crater on the rake face (KT), but the width of the crater on the rake face (KB) changes little; increasing the clearance angle reduces the wear on the flank; the smaller the graphite grain size, the longer the tool life; the tool life is roughly proportional to the bending strength and Shore hardness. (2) in terms of cutting force, the cutting force of graphite material is only 10% of that of cutting ductile metals such as aluminum and copper. When turning graphite material, the cutting force and its fluctuation amplitude increase with the increase of feed rate; the cutting force decreases with the increase of tool rake angle, but when the clearance angle increases to 60°C, the change in cutting force is no longer significant; the higher the material's bending resistance, the greater the cutting force; the influence of cutting speed on the cutting force in brittle materials can generally be neglected. (3) in terms of machined surface quality, increasing the cutting speed and cutting feed rate can degrade the surface quality; increasing the tool rake angle degrades the surface quality. Rough machining of graphite aims to remove a large amount of material in a short time, and can be achieved using contour milling or profile milling. The quality of the rough machining process depends on NC programming based on the tool surface contour curve function, enabling fast and simple milling along the envelope contour lines. During finishing, the treatment of corners should consider the impact of the milling direction on machining accuracy and surface quality. When milling along a curved surface, pull milling and drill milling phenomena may occur, and tool deformation can lead to deviations in the workpiece contour. The strategy for milling along a planar contour is to use a combination of up milling and planar contour milling. The main problem in machining prismatic surfaces is the fracture of local edges and corners of the mold, and the direction of the cutting force should be mainly considered. Currently, in China, the process parameters adopted in the high-speed machining strategies commonly used by graphite high-speed machining enterprises are mainly selected based on general principles relying on the experience of programmers. However, theoretical and applied research on programming strategies and process parameter optimization for special structural components has not yet been conducted.