Compared with most steel and cast iron materials, aluminum has many significant characteristics in physical properties: strength and hardness are much higher than pure aluminum, but lower than steel, cutting force is smaller, and thermal conductivity is good.
Because aluminum alloy CNC machining is soft, plastic, easy to stick to the tool, BUE is formed on the tool, and welding may occur on the blade during high-speed cutting, causing the tool to lose cutting ability, affecting machining accuracy and surface roughness. In addition, aluminum has a large thermal expansion coefficient, and cutting heat can easily cause thermal deformation of the workpiece and reduce machining accuracy.
In summary, the selection of cutting fluid for aluminum alloy CNC machining is very important, and good lubrication, cooling, filtration and rust prevention must be guaranteed. Therefore, the cutting fluid for aluminum CNC machining is different from ordinary cutting fluid, and it is crucial to choose the right cutting fluid.
Different cutting fluids should be selected according to the aluminum alloy CNC machining conditions and precision requirements. Since high-speed CNC machining will generate a lot of heat, such as high-speed cutting and drilling, if the heat generated cannot be taken away by the cutting fluid in time, sticking will occur, and even BUE will occur, which will seriously affect the machining roughness and tool life of the workpiece, and will also cause thermal deformation of the workpiece, seriously affecting the accuracy of the workpiece. Therefore, the selection of cutting fluid needs to consider its own lubricity and cooling performance.
For grinding, the grinding chips are very small, and a lot of heat will be generated during the grinding process. It is necessary to consider both the lubrication and cooling performance of the cutting fluid and the filtration of the cutting fluid. If the selected cutting fluid viscosity is too large, the chips cannot be deposited or filtered out, and it will scratch the surface of the workpiece processing area as the coolant circulates, thereby affecting the surface finish processing. Therefore, ultrafine grinding is selected for grinding or low-viscosity grinding oil or semi-synthetic cutting fluid for grinding and grinding.
When selecting cutting fluid, in addition to considering the lubrication and cooling properties of the cutting fluid, the corrosion resistance, cost and easy maintenance of the cutting fluid should also be considered. Cutting oil is easy to choose a relatively low-viscosity base oil anti-friction additive, which can achieve lubrication friction and good cooling and easy filtration. However, cutting oil has the problems of low flash point, large smoke during high-speed cutting, high risk factor, fast volatilization, and correspondingly high user cost. Therefore, water-soluble cutting fluid should be used as much as possible when conditions permit.
For water-based machining fluids, it is more important to consider rust prevention. Commonly used water-based rust inhibitors are aluminum silicate and phosphate esters. For long-term processing of workpieces, a cutting fluid phosphate ester rust inhibitor is easy to use during processing. As a silicon-based material, long-term contact corrosion with aluminum produces black "silicon spots". The pH value of the cutting fluid is maintained above 8-10. If the rust is not good, aluminum materials are easily corroded under alkaline conditions. Therefore, water-soluble cutting fluids must have good aluminum corrosion resistance.
