The polishing in mold processing is very different from the surface polishing required by other industries. Surface polishing usually only needs to obtain a bright surface, and mold polishing strictly speaking, it should be called mirror processing. Not only the polishing itself requires high, the surface of the flatness, smoothness, geometric accuracy also has a high standard.

The specific method of 1. mold mirror polishing
The process of mold mirror polishing is mainly to reduce the roughness of the surface of the workpiece. Different mold polishing schemes are given for different mold polishing, so there are several methods for mold polishing:
(1) mechanical polishing. This method mainly relies on cutting or plastic deformation of the surface of the material to remove the convex part of the surface to obtain a smooth surface. Usually use oilstone, wool wheel, sandpaper and other tools, mainly manual operation. For the mold with high surface quality requirements, the method of super polishing can be used. This method can use special abrasive tools and abrasive polishing liquid to achieve very high surface roughness.
(2) chemical polishing. Chemical polishing involves placing the mold in a chemical medium that preferentially dissolves the protruding portions of the surface by chemical action, resulting in a smooth surface. This method does not require complex equipment, can polish workpieces with complex shapes, and process multiple workpieces at the same time, but the surface roughness is generally only about 10 μm.
(3) electrolytic polishing. The principle of electrolytic polishing is similar to chemical polishing, and the surface is polished by selectively dissolving the tiny protruding parts of the mold surface. This method can eliminate the influence of cathode reaction and obtain better polishing effect.
(4) ultrasonic polishing. The workpiece is placed in the abrasive suspension and placed in the ultrasonic field, and the surface of the workpiece is ground and polished by the oscillation of the ultrasonic wave. This method has small macro force and will not cause deformation of the workpiece, but it is difficult to make and install the tooling.
(5) fluid polishing. This method relies on the high-speed flow of liquid and its carrying abrasive scour the surface of the workpiece to achieve polishing effect. Including abrasive jet processing, liquid jet processing, fluid dynamic grinding.
(6) magnetic grinding and polishing. The abrasive brush is formed by magnetic abrasive under the action of magnetic field to grind the workpiece.
These methods have their own characteristics and are suitable for different types of molds and different surface quality requirements. Which method to choose depends on the specific process requirements, equipment conditions and economic factors. The common way of mold polishing is the first three ways.

The benefits of 2. mold polishing
(1) After polishing, the mold cavity will be smoother, easier to demold during the production process, improve production efficiency, reduce production cycle, and achieve cost reduction.
(2) After polishing, the roughness of the mold is lower, and the flatness and smoothness are higher, so the appearance of the products produced is more atmospheric, beautiful, more acceptable, and easy to open the market.
(3) I believe many people know how high the cost of opening a set of molds is, so after many molds are polished, customers will perform electroplating, and the molds after electroplating have more wear resistance and corrosion resistance, which greatly extends the use of the molds. life.
(4) After the mold is polished, the precision of the mold clamping surface can be improved to prevent burrs and affect normal production.

Basic procedures for 3. hand polishing
In order to obtain a high-quality polishing effect, it is important to have high-quality polishing tools and accessories, such as oilstone, sandpaper, diamond grinding paste, etc., and then perform manual (manual) polishing. There is also a polished working environment that requires a dust-free workshop. The choice of polishing procedure depends on the surface condition after preliminary machining, such as machining, electric discharge machining, grinding, etc.

4. manual polishing should pay attention to what problems
Do not destroy the structure of the workpiece; do not destroy the rounded corners of the workpiece, and do not destroy the rationality of the demoulding slope; pay attention to the order of use of polishing tools; pay attention to the polishing strength.
When sanding with sandpaper, the following points should be noted:
(1) Use cork or bamboo sticks and sand paper. When polishing round or spherical surfaces, use a cork to better match the radian of the round and spherical surfaces. Harder wood, such as cherry wood, is more suitable for polishing flat surfaces. Trim the end of the wood strip to make it consistent with the surface shape of the steel part, so as to prevent the acute angle of the wood strip (or bamboo strip) from contacting the surface of the steel part and causing deep scratches.
(2) When using different types of sandpaper, the sanding direction should change between 45 ° and 90 °, and the stripes and shadows left by the previous sandpaper can be distinguished. Before replacing different types of sandpaper, the polishing surface must be carefully wiped with cleaning fluid, because small gravel remaining on the surface will destroy the entire polishing process. This cleaning process is also important when switching from sandpaper polishing to diamond paste polishing. Clean all particles and kerosene before continuing polishing.
(3) In order to avoid scratching and burning the surface of the workpiece, special care must be taken when sanding with #1200 and #1500 sandpaper. So to light load, with a two-step polishing method to polish the surface. When sanding with each type of sandpaper, it should be sanded twice in two different directions, rotating 45-90 degrees each time between the two directions.