1.1 mechanical polishing:

Mechanical polishing is a polishing method to obtain a smooth surface by cutting and plastic deformation of the surface of the material to remove the polished convex part. Generally, oilstone strips, wool wheels, sandpaper, etc. are used, mainly by manual operation. For special parts such as the surface of the rotary body, auxiliary tools such as turntables can be used, and the method of ultra-fine polishing can be used for high surface quality requirements. Super-finishing polishing is the use of special grinding tools, containing abrasive polishing fluid, tightly pressed on the workpiece is processed surface, for high-speed rotation.

1.2 chemical polishing

Chemical polishing is to make the surface of the material in the chemical medium micro convex part of the concave part of the preferential dissolution, so as to get a smooth surface. The main advantage of this method is that it does not require complex equipment, can polish workpieces with complex shapes, and can polish many workpieces at the same time, with high efficiency.

1.3 electrolytic polishing

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

1.4 ultrasonic polishing

The workpiece is placed in the abrasive suspension and placed together in the ultrasonic field, relying on the ultrasonic oscillation, so that the abrasive grinding and polishing on the surface of the workpiece. Ultrasonic machining macro force is small, will not cause deformation of the workpiece, but tooling production and installation is difficult. Ultrasonic machining can be combined with chemical or electrochemical methods. On the basis of solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution to separate the dissolved products on the surface of the workpiece, and the corrosion or electrolyte near the surface is uniform. The cavitation effect of ultrasonic wave in the liquid can also inhibit the corrosion process and is conducive to the surface brightening.

1.5 fluid polishing fluid polishing

Is to rely on high-speed flow of liquid and abrasive particles to wash the surface of the workpiece to achieve the purpose of polishing. Commonly used methods are: abrasive jet processing, liquid jet processing, fluid power grinding. Fluid power grinding is driven by hydraulic pressure, so that the liquid medium carrying abrasive particles flows through the surface of the workpiece at high speed. The medium is mainly made of a special compound (usually a polymer-like substance) with good flowability at a lower pressure, and the abrasive can be made of silicon carbide powder.

1.6 magnetic grinding and polishing

Magnetic grinding and polishing is the use of magnetic abrasive under the action of a magnetic field to form an abrasive brush to grind the workpiece. This method has high processing efficiency, good quality, easy control of processing conditions, and good working conditions.

2 The basic method of mechanical polishing The polishing in plastic mold processing is very different from the surface polishing required in other industries. To be precise, the polishing of the mold should be called mirror processing. It not only has high requirements for polishing itself, but also has high standards for surface flatness, smoothness and geometric accuracy. Surface polishing is generally required to obtain a bright surface.

2.1 basic mechanical polishing procedures in order to obtain high-quality polishing results, the most important thing is to have high-quality polishing tools and auxiliary products such as oilstone, sandpaper and diamond abrasive paste. The choice of polishing procedure depends on the surface condition after pre-processing, such as machining, EDM, grinding and so on. The general process of mechanical polishing is as follows:

(1) The surface after rough polishing, milling, electric spark, grinding and other processes can be polished at a rotating surface polishing machine or ultrasonic grinding machine. This is followed by manual oilstone grinding, and strips of oilstone plus kerosene as a lubricant or coolant.

(2) semi-precision polishing semi-precision polishing mainly uses sandpaper and kerosene.

(3) the main use of fine polishing polishing diamond grinding paste.