Common Polishing Methods for Titanium Alloy Screws and Their Working Principles

Titanium alloy screws often require polishing processes to improve surface quality, reduce roughness, enhance corrosion resistance, and meet precision manufacturing requirements. Common polishing methods include mechanical polishing, chemical polishing, electrolytic polishing, ultrasonic polishing, fluid polishing, magnetic abrasive polishing, and electrodischarge-ultrasonic composite polishing.

Mechanical polishing is a traditional polishing method that removes surface irregularities through cutting or plastic deformation, resulting in a smoother surface. Common tools include oil stones, wool wheels, and sandpaper, and the process is typically performed manually. For applications requiring extremely high surface quality, ultra-fine polishing can be applied. This method uses specially designed polishing tools pressed against the workpiece surface while rotating at high speed in a slurry containing abrasives. Ultra-fine polishing can achieve surface roughness values as low as Ra 0.008 μm, making it one of the most precise polishing techniques available. It is widely used for polishing precision molds, including optical lens molds.

Chemical polishing achieves surface smoothing by selectively dissolving microscopic protrusions on the material surface in a chemical medium. This method is suitable for workpieces with complex geometries and allows multiple components to be processed simultaneously, providing high production efficiency. The typical surface roughness achieved through chemical polishing is approximately Ra 10 μm.

Electrolytic polishing operates on a similar principle to chemical polishing, where microscopic surface peaks are selectively dissolved to improve smoothness. Compared with chemical polishing, electrolytic polishing reduces the influence of cathodic reactions, resulting in a cleaner surface and better polishing quality. It is commonly used when higher surface finish and improved surface performance are required.

Ultrasonic polishing uses high-frequency ultrasonic vibrations generated by a tool to drive abrasive particles in a slurry, allowing them to impact and polish the workpiece surface. The workpiece is immersed in an abrasive suspension and exposed to an ultrasonic field, where the vibration of abrasives removes surface irregularities. Since the applied macroscopic force is relatively small, this method causes minimal deformation of the workpiece. However, the fabrication and installation of specialized tooling can be relatively challenging.

Fluid polishing utilizes a flowing liquid containing abrasive particles to remove material from the workpiece surface. In fluid dynamic grinding, a hydraulic system drives a special polymer-based compound mixed with abrasives through the surface area at low pressure. Abrasives such as silicon carbide powder can be used to enhance the polishing effect. This method is particularly suitable for processing complex surfaces and improving surface uniformity.

Magnetic abrasive polishing uses magnetic abrasives controlled by an external magnetic field to form flexible abrasive brushes. These abrasive brushes move along the workpiece surface and remove microscopic defects through grinding action. This technique offers high processing efficiency, excellent surface quality, and easily adjustable processing parameters. With appropriate abrasive materials and conditions, surface roughness values can reach approximately Ra 0.1 μm.

Electrodischarge-ultrasonic composite polishing combines ultrasonic vibration with a high-frequency pulse power supply featuring narrow pulse widths and high peak currents. The combined effects of ultrasonic impact and electrical discharge rapidly remove surface irregularities and significantly reduce roughness. This method is particularly effective for improving the surface quality of titanium alloy screws after machining processes such as turning, milling, electrical discharge machining (EDM), and wire cutting.

Overall, different polishing methods provide various advantages depending on the required surface quality, workpiece geometry, and processing conditions. For titanium alloy screws, selecting an appropriate polishing technique is essential for achieving the desired surface finish, dimensional accuracy, and functional performance.