Mechanical polishing:

Principle: By relying on cutting and material surface plastic deformation to remove polished protrusions, a smooth surface is obtained.

Tools: Oil stone strips, wool wheels, sandpaper, etc. are generally used, with manual operation being the main method. For special parts such as rotating surfaces, auxiliary tools such as turntables can be used. For those with high surface quality requirements, the ultra precision grinding and polishing method can be used, which involves using specially designed grinding tools to press tightly against the surface of the workpiece being processed in a grinding and polishing liquid containing abrasives, and perform high-speed rotational motion.

Effect: The use of ultra precision polishing technology can achieve a surface roughness of Ra0.008 μ m, which is the highest among various polishing methods. This method is commonly used for optical lens molds.

Chemical polishing:

Principle: Allow the micro protruding parts of the material's surface to dissolve preferentially in the chemical medium, resulting in a smooth surface.

Advantages: No need for complex equipment, can polish workpieces with complex shapes, can polish many workpieces at the same time, high efficiency.

Core issue: Preparation of polishing solution. The surface roughness obtained by chemical polishing is generally tens of micrometers.

Electrolytic polishing:

Principle: Similar to chemical polishing, it relies on 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 cathodic reactions and achieve better results.

Process: The electrochemical polishing process is divided into two steps. The first step is macroscopic leveling, where the dissolved products diffuse into the electrolyte and the geometric roughness of the material surface decreases, Ra>1μm。 The second step is to achieve low light leveling, anodic polarization, and increase surface brightness, Ra<1μm。

Ultrasonic polishing:

Principle: Place the workpiece in an abrasive suspension and place it together in an ultrasonic field. By relying on the oscillation effect of ultrasonic waves, the abrasive is ground and polished on the surface of the workpiece.

Characteristics: Ultrasonic machining has low macroscopic force and will not cause deformation of the workpiece, but it is difficult to manufacture and install the fixture. Ultrasonic processing can be combined with chemical or electrochemical methods. Based on solution corrosion and electrolysis, ultrasonic vibration is applied to stir the solution, causing the dissolved products on the surface of the workpiece to detach and the corrosion or electrolyte near the surface to be uniform. The cavitation effect of ultrasound in liquid can also suppress the corrosion process and promote surface brightening.

Fluid polishing:

Principle: The purpose of polishing is achieved by flushing the surface of the workpiece with high-speed flowing liquid and its carried abrasive particles.

Common methods: abrasive jet machining, liquid jet machining, fluid dynamic grinding, etc. Fluid dynamic grinding is driven by hydraulic pressure, which causes the liquid medium carrying abrasive particles to flow back and forth at high speed over the surface of the workpiece. The medium is mainly made of special compounds (polymer like substances) with good flowability at lower pressures and mixed with abrasives, which can be made of silicon carbide powder.

Magnetic grinding and polishing:

Principle: Utilizing magnetic abrasives to form abrasive brushes under the action of a magnetic field for grinding and processing workpieces.

Advantages: High processing efficiency, good quality, easy control of processing conditions, and good working conditions. By using appropriate abrasives, the surface roughness can reach Ra0.1 μ m.