A Comprehensive Analysis of Titanium Alloy Screw Mold Polishing Methods

In the process of industrial products moving towards diversification, improving the quality of molds that directly affect product quality has become a key task. In the manufacturing process of titanium alloy screw molds, the smooth processing and mirror finish processing after shape processing, that is, the surface grinding and polishing processing of the parts, are important procedures for improving mold quality.

Mastering the appropriate polishing method not only can enhance the quality and service life of titanium alloy screw molds, but also can further guarantee product quality.

1. Mechanical Polishing
Mechanical polishing removes the protruding parts on the surface of the workpiece through cutting or inducing plastic deformation of the material, thereby obtaining a smooth surface. Tools such as oilstone strips, wool wheels, sandpaper, etc. are usually used, with manual operation being the main method. For workpieces with higher surface quality requirements, the method of ultra-precision grinding and polishing can be adopted. Ultra-precision grinding and polishing uses specially made grinding tools, which are pressed tightly onto the processed surface of the workpiece in the polishing liquid containing abrasive materials, and perform high-speed rotational movement. With this technology, the surface roughness of the workpiece can reach Ra0.008 μm, which is the lowest surface roughness among many polishing methods. Optical lens molds often adopt this method. Mechanical polishing occupies a dominant position in the field of mold polishing.

II. Chemical Polishing
Chemical polishing is a process where the material is placed in a chemical medium, causing the microscopic protrusions on the surface to dissolve more readily than the depressions, thereby resulting in a smooth surface. This method can polish complex-shaped workpieces and can simultaneously polish multiple workpieces, with high efficiency. However, the surface roughness obtained through chemical polishing is generally around Ra10μm.

III. Electrolytic Polishing
The basic principle of electrolytic polishing is similar to that of chemical polishing. Both rely on the selective dissolution of the tiny protrusions on the material's surface to make the surface smooth. Compared with chemical polishing, electrolytic polishing can eliminate the influence of cathodic reactions and offers better polishing results.

IV. Ultrasonic Polishing
Ultrasonic polishing utilizes the cross-section of the tool to vibrate under ultrasonic waves. It uses a suspension of abrasive particles to process brittle and hard materials. The specific operation is to place the workpiece in the abrasive suspension and simultaneously place it in the ultrasonic field. By relying on the oscillating effect of the ultrasonic waves, the abrasive particles perform grinding and polishing on the surface of the workpiece. The macroscopic force of ultrasonic processing is relatively small, which does not cause the workpiece to deform. However, the manufacturing and installation of the tooling are relatively difficult.

V. Fluid Polishing
Fluid polishing achieves the polishing effect by using flowing liquid and the abrasive particles it carries to scour the surface of the workpiece. Fluid power grinding is driven by hydraulic power. The medium mainly consists of special compounds (polymeric substances) with good fluidity under low pressure, which are mixed with abrasive materials to form. The abrasive can be silicon carbide powder.

VI. Magnetic Grinding and Polishing
Magnetic grinding and polishing utilizes magnetic abrasive materials to form abrasive brushes under the influence of a magnetic field, and then performs grinding on the workpiece. This method has high processing efficiency, good quality, and the processing conditions are easy to control. By using the appropriate abrasive, the surface roughness after processing can reach Ra0.1 μm.

VII. Electrospark Ultrasonic Composite Polishing
To increase the polishing speed of workpieces with a surface roughness Ra of 1.6 μm or above, a combined polishing method using ultrasonic waves and a dedicated high-frequency narrow pulse peak current pulse power supply can be adopted. This combined polishing method combines the advantages of ultrasonic waves and electrical discharge polishing, effectively enhancing the polishing efficiency and quality.

Different polishing methods have their own characteristics and applicable scopes. In the actual polishing process of titanium alloy screw molds, based on the specific requirements of the molds, the complexity of the shapes, and the surface roughness requirements, it is necessary to select the appropriate polishing method or combine the use of multiple methods to achieve the desired polishing effect, improve the quality of the molds, and lay the foundation for the production of high-quality titanium alloy screw products.