A Comprehensive Analysis of Polishing Methods for Titanium Alloy Screw Molds

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 processing after shape processing, that is, the surface grinding and polishing processing of parts, are important procedures for enhancing the quality of molds.

Mastering the appropriate polishing methods can not only enhance the quality and service life of titanium alloy screw molds, but also further ensure product quality. Next, we will introduce several commonly used mold polishing methods and their working principles in detail.

I. Mechanical Polishing Mechanical polishing removes the protruding parts on the workpiece surface by cutting or causing plastic deformation on the material surface, thereby obtaining a smooth surface. Usually, tools such as oilstone strips, wool wheels, and sandpaper are used, and manual operation is the main method. For workpieces with high surface quality requirements, superfinishing polishing can be adopted. Superfinishing polishing uses specially made grinding tools, which are tightly pressed against the workpiece surface to be processed in a polishing liquid containing abrasive materials and perform high-speed rotational motion. With this technology, the surface roughness of the workpiece can reach Ra0.008μm, which is the lowest among various polishing methods. Optical lens molds often use this method. Mechanical polishing holds a dominant position in the field of mold polishing.

II. Chemical Polishing
Chemical polishing involves immersing the material in a chemical medium, where the microscopic protrusions on the surface dissolve preferentially over the recesses, thereby achieving a smooth surface. This method can polish workpieces with complex shapes and can simultaneously polish multiple workpieces, making it highly efficient. However, the surface roughness obtained through chemical polishing is generally Ra10μm.

III. Electrolytic Polishing
The basic principle of electrolytic polishing is similar to that of chemical polishing, both relying on the selective dissolution of the minute protrusions on the material surface to make it smooth. Compared with chemical polishing, electrolytic polishing can eliminate the influence of cathodic reactions and achieve a better polishing effect.

IV. Ultrasonic Polishing
Ultrasonic polishing utilizes the ultrasonic vibration of the tool's cross-section to process brittle and hard materials with the aid of abrasive suspension. Specifically, the workpiece is placed in the abrasive suspension and both are put into the ultrasonic field. Relying on the oscillation effect of ultrasonic waves, the abrasives perform grinding and polishing on the surface of the workpiece. The macroscopic force of ultrasonic processing is relatively small, which will not cause deformation of the workpiece, but the manufacturing and installation of the fixture are relatively difficult.

V. Fluid Polishing
Fluid polishing relies on the flow of liquid and the abrasive particles it carries to scour the surface of the workpiece, thereby achieving the polishing purpose. Fluid power grinding is driven by hydraulic pressure, and the medium mainly uses special compounds (polymer-like substances) with good fluidity at lower pressures, and is mixed with abrasives to make it. The abrasive can be silicon carbide powder.

VI. Magnetic Abrasive Polishing
Magnetic abrasive polishing utilizes magnetic abrasives to form abrasive brushes under the influence of a magnetic field, for grinding workpieces. This method features high processing efficiency, good quality, and easy control of processing conditions. With the use of appropriate abrasives, the surface roughness of the processed workpiece can reach Ra0.1μm.

VII. Electrical Discharge Ultrasonic Compound Polishing
To increase the polishing speed of workpieces with a surface roughness Ra of 1.6 μm or more, a combined polishing method using ultrasonic waves and a dedicated high-frequency narrow pulse with a high peak current pulse power supply can be adopted. This combined polishing approach integrates the advantages of ultrasonic and electrospark polishing, effectively enhancing polishing efficiency and quality.

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