In the process of diversification and high-grade development of industrial products, how to improve the quality of mold, which directly affects the quality of products, is an important task. In the process of titanium alloy screw mold manufacturing, the smooth processing and mirror processing after shape processing are called parts surface grinding and polishing processing, which is an important process to improve the quality of the mold. Mastering a reasonable polishing method can improve the quality and service life of titanium bolts, and then improve product quality.

Common polishing methods and working principles

01 Mechanical polishing

Mechanical polishing is by cutting or making the surface of the material plastic deformation and remove the workpiece surface bulge to get a smooth polishing method, the general use of stone strip, wool wheel, sandpaper, etc., mainly manual operation, surface quality requirements can be high polishing method. Super finishing polishing is the use of special grinding tools, in the polishing liquid containing abrasive, tightly pressed on the workpiece to be machined surface, for high-speed rotation. The surface roughness of Ra0.008μm can be achieved by using this technology, which is the best surface roughness among various polishing methods. This method is often used in optical lens molds. Mechanical polishing is the main method of mold polishing.

02 Chemical polishing

Chemical polishing is the material in the chemical medium so that the surface of the micro-convex part is preferentially dissolved than the concave part, so as to obtain a smooth surface. This method can polish the titanium bolts with complex shape, and can polish many workpieces at the same time, with high efficiency. The surface roughness obtained by chemical polishing is generally Ra10 μm.

03 Electrolytic polishing

The basic principle of electrolytic polishing is the same as that of chemical polishing, that is, by selectively dissolving small protruding parts on the surface of the material to make the surface smooth. Compared with chemical polishing, it can eliminate the influence of cathode reaction, and the effect is better.

04 Ultrasonic polishing

Ultrasonic polishing is a processing method of polishing brittle and hard materials by abrasive suspension by using tool section to make ultrasonic vibration. Titanium bolt is put into the abrasive suspension and placed together in the ultrasonic field, and the abrasive is ground and polished on the workpiece surface by relying on the oscillation of the ultrasonic wave. Ultrasonic processing macroscopic force is small, will not cause workpiece deformation, but tooling production and installation is more difficult.

05 Fluid Polishing

Fluid polishing is the purpose of polishing the titanium bolts surface by washing the flowing liquid and the abrasive particles carried by it. Hydrodynamic grinding is driven by hydraulic pressure, and the medium is mainly made of special compounds (polymer-like substances) with good flow under low pressure and incorporated into abrasive, abrasive can be made of silicon carbide powder.

06 Magnetic grinding and polishing

Magnetic grinding and polishing is the use of magnetic abrasive under the action of magnetic field to form an abrasive brush, grinding the workpiece. This method has the advantages of high processing efficiency, good quality and easy control of processing conditions. With suitable abrasive, titanium bolts surface roughness can reach Ra0.1μm.

07 EDM ultrasonic composite polishing

In order to improve the polishing speed of the titanium bolts whose surface roughness Ra is more than 1.6μm, ultrasonic wave and special pulse power supply with high frequency narrow pulse peak current are used for composite polishing. Ultrasonic vibration and corrosion of electric pulse act on the surface of the workpiece at the same time to rapidly reduce its surface roughness. This is very effective for polishing the rough surface of the die after machining by turning, milling, EDM and wire cutting.