Mold polishing knowledge, valuable mold information, not to be missed!

In the process of diversification of industrial products, how to improve the quality of molds that directly affect product quality is an important task. In the mold manufacturing process, shape processing after the smooth processing and mirror processing called parts surface grinding and polishing processing, it is to improve the quality of the mold is an important process. Mastery of reasonable polishing methods, can improve the quality and service life of the mold, and thus improve product quality.     

1 common polishing methods and working principle  

1.1 Mechanical polishing  

Mechanical polishing is by cutting or plastic deformation of the surface of the material to remove the surface of the workpiece protruding part of the smooth surface of the polishing method, the general use of oil stone strips, wool wheels, sandpaper, etc., mainly hand-operated, the surface of the surface of high quality requirements can be used in the ultra-fine research and polishing methods. Ultra-precision research and polishing is the use of special abrasives, in the research and polishing liquid containing abrasives, tight pressure on the surface of the workpiece being processed, for high-speed rotary motion. Using this technique, the surface roughness of Ra0.008 μm can be achieved, which is a good surface roughness among various polishing methods. Optical lens molds often use this method. Mechanical polishing is the main method of mold polishing.   

1.2 chemical polishing  

Chemical polishing is the material in the chemical medium so that the surface microscopic convex part of the concave part of the priority of the dissolution, so as to get a smooth surface. This method can polish the complex shape of the workpiece, can be polished at the same time many workpieces, high efficiency. The surface roughness obtained by chemical polishing is generally Ra10 μm. 

1.3 Electrolytic polishing 

 The basic principle of electrolytic polishing is the same as that of chemical polishing, that is, by selectively dissolving the tiny protruding parts of the material surface, so that the surface is smooth. Compared with chemical polishing, it can eliminate the influence of cathodic reaction, the effect is better.  

1.4 Ultrasonic polishing  

Ultrasonic polishing is the use of tool sections for ultrasonic vibration, through the abrasive suspension polishing brittle hard materials, a processing method. The workpiece is put into the abrasive suspension and placed together in the ultrasonic field, relying on the oscillation of ultrasonic waves, so that the abrasive grinding and polishing on the surface of the workpiece. Ultrasonic processing macro force is small, will not cause deformation of the workpiece, but the production and installation of equipment is more difficult. 

1.5 Fluid polishing  

Fluid polishing is to rely on the flow of liquid and the abrasive particles it carries to flush the surface of the workpiece to achieve the purpose of polishing. Fluid power polishing is driven by hydraulic pressure, the media is mainly used in the lower pressure flow through the good special compounds (polymer-like substances) and mixed with abrasive made of abrasive can be used silicon carbide powder.   

1.6 Magnetic grinding and polishing 

Magnetic grinding and polishing is the use of magnetic abrasives in the magnetic field under the action of the formation of abrasive brushes, grinding and processing of the workpiece. This method has high processing efficiency and good quality, and the processing conditions are easy to control. Using suitable abrasives, the surface roughness of the processing can reach Ra0.1 μm.    

1.7 EDM ultrasonic compound polishing  

In order to improve the surface roughness Ra for more than 1.6 μm workpiece polishing speed, the use of ultrasonic and special high-frequency narrow pulse high peak current pulse power supply for composite polishing, by the ultrasonic vibration and electrical pulse corrosion at the same time act on the surface of the workpiece to rapidly reduce its surface roughness, which is processed by the car, milling, EDM and wire cutting and other crafts after the rough surface of the mold polished effect is obvious, very effective.     

2 mold polishing commonly used tools and specifications categories  

Mold polishing tools are commonly used: sandpaper, oil stone, felt wheel, abrasive paste, alloy files, diamond grinding needles, bamboo, fiber oil stone, round rotating grinding machine.   

Sandpaper:150#,180#,320#,400#,600#,800#,1,000#,1,200#,1,500#;   

Oil stone:120#,220#,400#,600#; Flannel wheel:cylindrical,round vertebrae,square tip;   

Abrasive paste: 1# (white) 3# (yellow) 6# (orange) 9# (green) 15# (blue) 25# (brown) 35# (red) 60# (purple);   

Files:square,round,flat,triangular and other shapes;   

Diamond grinding needles: generally 3/32 shank or 1/8 shank, round wave shape, cylindrical, long straight column, long round vertebrae;   

Bamboo: various shapes suitable for the operator and mold shape and manufacturing, the role is to press the sandpaper, grinding on the workpiece to achieve the required surface roughness;  

 Fiber oil stone: 200 # (black) 400 # (blue) 600 # (white) 800 # (red).    

 3 Polishing process  

3.1 Rough polishing  

Fine milling, EDM