1.Introduction of grinding fluids for CBN wheel
CBN high-speed grinding has become a widely used grinding method with excellent machining accuracy and grinding performance. With the rise of ultra-high-speed grinding in recent years, broking through the previous grinding efficiency limit, achieving high performance grinding of difficult-to-grind materials, making the ability and application of grinding processing expanded, it is a new processing technology that can compete with machining such as turning, milling and planer.
The high temperature in the grinding zone formed by high-speed grinding will cause excessive wear of CBN grinding wheel, which will deteriorate the surface integrity of the workpiece and seriously affect the improvement of the machining accuracy of the part. Therefore, it is of great significance to further improve the application level of CBN grinding technology by selecting the appropriate grinding fluid and the related application technology for the development of grinding fluid for CBN high speed grinding.
At present, comprehensive research on grinding fluids has attracted attention as a major support technology for high-speed grinding and has become an important part of this integrated high-tech field.
2.Selection of grinding fluids for CBN wheel
The functions of the grinding fluid mainly include the following 4 aspects(1)lubrication, (2)cooling,(3) cleaning, and (4) rust-proof. For CBN high speed grinding, because of high efficiency and high heat, it requires high lubrication performance and cooling performance of high speed grinding fluid. In addition, pay attention to the other functions, that is, corrosion resistance, fire resistance, defoaming, harmlessness, and antioxidant stability.
The lubrication function of the oil-based grinding fluid (mineral oil) is superior to that of water-based grinding fluid. It not only prevents the abrasion of CBN grain cutting edge, but also inhibits the hydrolysis reaction of CBN, improves the durability of the grinding wheel, and can effectively reduce the grinding efficiency, and reduce the grinding heat and improve the surface integrity of the workpiece.
If adding the sulfur-based and chlorine-based extreme pressure additive into the oil-based grinding fluid, it can obtain the superior effect. This is particularly true in high efficiency deep grinding based on ultra-high-speed grinding. At the same removal rate, the use of oil-based grinding fluid can increase the grinding ratio by 5-10 times or more, and the higher the speed, the more obvious the effect.
However, the oil-based grinding fluids have big oil mist during working, and it smokes and fires. So, for the use of oil-based grinding fluids, use fire safety protection and reliable oil and gas separation technology. Try to replace the oil-based grinding fluid with the special water-based grinding fluid containing a large number of surfactants, oily agents and extreme pressure additives, enhancing safety performance and reducing the comprehensive application cost of the grinding fluid.
Low foam grinding fluids should be sued on the closed CBN high efficiency grinding machines. Otherwise, as the flow rate of the grinding fluid increases and the pressure increases, the foam in the grinding fluid will seriously affect the actual liquid supply of the grinding fluid, so that the grinding zone is not sufficiently cooled and lubricated. Preventing premature corrosion of the grinding fluid is another important factor related to the grinding efficiency. Frequent replacement of the grinding fluid will greatly reduce the grinding quality of the workpiece and the efficiency of the grinding process.
Due to the special orientation of CBN grinding wheel and its objects, the selection of right grinding fluids for CBN wheel can greatly improve the grinding efficiency, safety, and quality of the product.