Industry information

Method and technology of mold polishing

2021-06-10

Method and technology of mold polishing

Polishing not only increases the beauty of the workpiece, but also can improve the corrosion resistance and wear resistance of the surface of the material. It can also make the mold have other advantages, such as making plastic products easy to demoulding and reducing the production injection cycle.Therefore, polishing is a very important process in the process of plastic mold production.

 

At present, there are several commonly used polishing methods:

1.1 Mechanical polishing

Mechanical cutting, polishing is to rely on material surface plastic deformation after removed by polishing the convex part of the smooth surface polishing method, commonly used article oil stone, wool wheel, abrasive paper, etc., with manual operation is given priority to, special components such as surface of solid of revolution, can use tools such as turntable, high surface quality can be used over lapping method.Super-fine grinding and polishing is made of special abrasive tools. In the grinding and polishing liquid containing abrasive materials, the workpiece is pressed tightly on the machined surface to make high-speed rotating motion.The surface roughness of RA0.008μm can be achieved by using this technique, which is the highest among various polishing methods.This method is often used in optical lens moulds.

 

1.2 Chemical polishing

Chemical polishing is to make the convex part of the surface of the material in the chemical medium is preferred to the concave part of the dissolution, so as to get a smooth surface.The main advantage of this method is that it does not need complex equipment, can polish the workpiece of complex shape, can polish many workpiece at the same time, high efficiency.The key problem of chemical polishing is the preparation of polishing fluid.The surface roughness obtained by chemical polishing is generally 10μm.

 

1.3 Electrochemical polishing

The basic principle of electropolishing is the same as that of chemical polishing, which selectively dissolves the tiny protrusions on the surface of the material to make the surface smooth.Compared with chemical polishing, the effect of cathodic reaction can be eliminated and the effect is better.

 

The electrochemical polishing process is divided into two steps:

(1) The solution of macroleveling diffuses into the electrolyte, and the geometrical roughness of the material surface decreases, and Ra > 1μm.

 

(2) The anodic polarization of low light level increases the surface brightness, and Ra is less than 1μm.

 

1.4 Ultrasonic polishing

The workpiece is put into the abrasive suspension and placed together in the ultrasonic field, and the abrasive is grinding and polishing on the surface of the workpiece by relying on the oscillation of the ultrasonic wave.Ultrasonic machining has small macroscopic force and will not cause the deformation of the workpiece, but it is difficult to make and install the tooling.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, so that the dissolved products on the surface of the workpiece are separated, and the corrosion or electrolyte near the surface is uniform.Ultrasonic cavitation in the liquid can also inhibit the corrosion process, which is conducive to surface lighting.

 

1.5 Fluid polishing

Fluid polishing is to rely on the high-speed flow of liquid and its 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, etc.Hydrodynamic grinding is driven by hydraulic pressure, which makes the liquid medium carrying abrasive particles flow through the workpiece surface at high speed.The medium is mainly made of special compounds with good fluidity under low pressure (polymer material) and mixed with abrasive, which can be made of silicon carbide powder.

 

1.6 Magnetic grinding and polishing

Magnetic abrasive polishing is the use of magnetic abrasive under the action of the magnetic field to form an abrasive brush, the workpiece grinding processing.This method has the advantages of high processing efficiency, good quality, easy control of processing conditions and good working conditions.With suitable abrasive, the surface roughness can reach Ra0.1μm.

Specific process to be continued