In the wide application of titanium alloy materials, titanium rods, as one of the best, its processing quality is directly related to the performance and appearance of the final product. In order to realize the smooth appearance of titanium rods and achieve the high standard of accuracy such as H11, H9, H8, H7, etc., the centerless grinder has become an indispensable key equipment. In this paper, we will discuss in depth the grinding characteristics of titanium alloy bar on centerless grinder, and how to optimize the process and equipment to achieve high-precision machining.
Advantages of centerless grinding machine
Centerless grinding machine can achieve high efficiency and precision grinding with its unique processing method, i.e. no workpiece axis positioning is required. The machine consists of three mechanisms: the grinding wheel, the adjusting wheel, and the workpiece holder, which work in tandem to respond flexibly to a variety of processing needs. Especially for titanium alloy and other high-strength, high-hardness materials, centerless grinding machines show excellent processing capabilities.
Five characteristics of titanium alloy grinding
High hardness: the hardness of titanium alloy is usually between HV350 and 400, which poses a serious challenge to the grinding tools and easily leads to tool loss and breakage.
Low thermal conductivity: The low thermal conductivity of titanium alloy makes the heat pile up quickly when grinding, and the cutting fluid is difficult to be discharged effectively, which affects the processing surface quality.
Susceptible to oxidation: under high temperature and high pressure environment, titanium alloy is easy to oxidize, affecting the surface quality, need to use suitable grinding fluid to strengthen the cooling and lubrication.
Tool adhesion and wear: The friction between grinding wheel and titanium alloy generates high temperature, which leads to the deformation of titanium alloy and adhesion to the grinding wheel, accelerating the wear of the grinding wheel.
Cold hardening phenomenon: the high temperature generated by grinding causes chemical reaction on the surface of titanium alloy, resulting in surface hardening and increasing the processing difficulty.
The art of grinding wheel selection
For the grinding characteristics of titanium alloy, the choice of grinding wheel is of vital importance. Silicon carbide grinding wheels are preferred for their high hardness and low wear characteristics, while cubic boron nitride and polycrystalline diamond are widely used in high-end machining for their high temperature resistance and stability. The selection of these grinding wheel materials is aimed at reducing grinding temperatures and improving grinding quality.
Importance of coolant
During centerless grinding, the coolant is not only a coolant, but also a cleaning agent. It needs to have the ability to carry away heat quickly and at the same time effectively rinse away fine sand from the surface of the product and residues from the surface of the grinding wheel. The use of water-soluble grinding fluids with a variety of extreme pressure additives can further improve machining results and reduce positioning errors.
Optimization of grinding parameters
The setting of grinding parameters has a direct impact on processing quality. Taking TC4φ10 titanium rods as an example, through repeated tests and accumulation of experience, we have concluded that the optimal grinding depth is 0.05~0.1mm and the optimal wheel speed is 25m/s. Under this parameter combination, the wheel adhesion rate is minimized and the grinding surface quality is optimal.
With the continuous expansion of the application field of titanium alloy materials, the machining precision and performance requirements for titanium alloy bars are getting higher and higher. By continuously optimizing the process parameters of the centerless grinder and selecting the appropriate grinding wheel and coolant, we are able to achieve high-precision and high-quality machining of titanium alloy bars. In the future, with the advancement of technology and the upgrading of equipment, we have reason to believe that the machining level of titanium alloy materials will step up to a new level.
