In the process of diversification and high-grade development of industrial products, how to improve the quality of molds that directly affect product quality is an important task. In the mold manufacturing process, smoothing and mirroring after shape processing is called part surface grinding and polishing, which is an important process to improve mold quality. Mastering a reasonable polishing method can improve the quality and service life of the mold, thereby improving the quality of the product.
1. Commonly used polishing methods and working principles
(1). Mechanical polishing Mechanical polishing is a polishing method that removes the protrusions on the surface of the workpiece by cutting or plastic deformation of the material surface to obtain a smooth surface. Generally, oil stone sticks, wool wheels, sandpaper, etc. are used. Manual operation is the main method. Those with high surface quality requirements can be used. The method of super-precision polishing. Ultra-precision polishing is the use of special abrasive tools, which are pressed tightly on the processed surface of the workpiece in a polishing fluid containing abrasives for high-speed rotation. The surface roughness of Ra0.008 μm can be achieved by using this technology, which is a banned word for surface roughness in various polishing methods. Optical lens molds often use this method. Mechanical polishing is the main method of mold polishing.
(2). Chemical polishing Chemical polishing is the process of dissolving the microscopically protruding part of the surface in a chemical medium preferentially than the concave part, so as to obtain a smooth surface. The method can polish workpieces with complex shapes, and can polish many workpieces at the same time, with high efficiency. The surface roughness obtained by chemical polishing is generally Ra10 μm.
(3). Electrolytic polishing The basic principle of electrolytic polishing is the same as that of chemical polishing, that is, it relies on the selective dissolution of small protrusions 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.
(4).Ultrasonic polishing Ultrasonic polishing is a processing method that uses the tool section to make ultrasonic vibrations and polishes brittle and hard materials through abrasive suspensions. Put the workpiece in the abrasive suspension and put it together in the ultrasonic field, relying on the oscillation effect of the ultrasonic, so that the abrasive is ground and polished on the surface of the workpiece. Ultrasonic machining has a small macroscopic force and will not cause deformation of the workpiece, but it is difficult to manufacture and install tooling.
(5). Fluid polishing Fluid polishing relies on flowing liquid and the abrasive particles carried by it to wash the surface of the workpiece to achieve the purpose of polishing. Hydrodynamic grinding is driven by hydraulic pressure. The medium is mainly made of special compounds (polymer-like substances) with good flowability under lower pressure and mixed with abrasives. The abrasives can be made of silicon carbide powder.
(6). Magnetic grinding and polishing Magnetic abrasive polishing is to use magnetic abrasives to form abrasive brushes under the action of a magnetic field to grind the workpiece. This method has high processing efficiency, good quality and easy control of processing conditions. Using suitable abrasives, the processed surface roughness can reach Ra0.1 μm.
(7). EDM ultrasonic composite polishing In order to improve the polishing speed of the workpiece with a surface roughness Ra of 1.6 μm or more, ultrasonic and a special high-frequency narrow pulse high-peak current pulse power supply are used for composite polishing. The corrosion of ultrasonic vibration and electric pulse acts on the surface of the workpiece at the same time, which rapidly reduces Its surface roughness is very effective in polishing the rough surface of the mold after machining by turning, milling, EDM and wire cutting.
Post time: Sep-16-2021