The choice of tool material for machining magnesium alloys depends on the amount of machining that needs to be done. When processing small batches, ordinary carbon steel tools with a particularly long service life are generally used; when processing large batches, carbide-inlaid tools are usually preferred; when processing batches are large and tolerance requirements are strict, higher-cost diamond-inlaid tools can be used. To save the tedious reset compensation adjustment work.
Tools for machining steel and aluminum are generally also suitable for machining magnesium alloys. However, due to the low cutting force and relatively low heat capacity of magnesium, the machining tool should have a large external clearance angle, a large chip clearance, a small number of cutting edges and a small rake angle. In addition, it is important to ensure that the surfaces of the tool are smooth. 1.3.3 Tool sharpening
An important principle of machining magnesium alloys is that the tool should be kept as sharp and smooth as possible and must be free of scratches, burrs and curling edges. If the tool has cut other metals, even if the cutting angle has not changed, it should be re-sharpened and sharpened.
A medium-grained grinding wheel can be used for initial grinding of the tool, then a fine-grained grinding wheel is used for sharpening, and if necessary, a fine or ultra-fine oilstone is used for manual honing. For high-speed steel tools, 100-mesh alumina grinding wheel can be used for fine grinding to obtain satisfactory results; for sharpening tools inlaid with cemented carbide, 320-mesh silicon carbide grinding wheels or 200-300-mesh diamond grinding wheels are generally used. 1.4 Influence of cutting fluid on machining
Cutting fluid has two functions, cooling and lubrication. Due to the rapid heat dissipation of magnesium, the temperature of the machined surface can be kept at a lower level. In addition, the easy machinability of magnesium makes it difficult to glue with steel, and lubrication is generally not required during cutting.
When machining magnesium alloy parts, no matter with high or low cutting speed, with or without cutting fluid, a smooth machined surface can be obtained, and the use of cutting fluid is mainly to cool the workpiece and reduce the distortion of the parts and the ignition of chips as much as possible. possibility. Therefore, in the machining of magnesium alloy parts, the cutting fluid is generally called coolant. When producing large batches, coolant is one of the factors that prolong tool life.
The coolant is generally mineral oil. Mineral sealing oils and kerosene have been successfully used as coolants for magnesium alloy machining. For better cooling, the cutting oil should have a lower viscosity. In order to prevent corrosion of magnesium alloy parts, the free acid content in the cutting fluid should be less than 0.2%.