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China mainly uses sandpaper, abrasive belt, PVA grinding wheel or even grinding paste to process outer round fine grinding or fine polishing. Sandpaper and mortar are required to be operated by skilled workers, and the efficiency is very low. Although the abrasive belt and PVA wheel are highly efficient in large-area processing, the ultra-precision grinding effect is not ideal due to the limitations of the tool itself and the machine. At present, foreign countries such as the United States and Japan have successfully developed a precision grinding system for grinding films, which makes the polishing effect of processed products more precise and consistent.

The 3M company's precision grinding system mainly uses a film coated with abrasive material to be processed in a single direction. The grinding and polishing contact surfaces are all unused high-precision abrasives. Since the abrasive is not reused, the disadvantages of the first and last polishing effects of the workpiece during the general polishing are avoided. The advantages of the 3M precision grinding system also include ensuring that the shape of the workpiece itself does not produce oscillating and vibrating lines. The grinding wheel is easy to replace, easy to operate, and can save up to 50% of working time, and the polishing effect is more precise (<0.025~μm).

The abrasive film is an abrasive tool which uniformly coats several tens of μm of fine abrasive grains with a synthetic resin binder on a mylar film substrate having a thickness of about 25 to 100 μm.

The structure of the abrasive film has four major elements:

(1) Substrate: Polyester film 857 (PET) has large tensile strength in the longitudinal and transverse directions, small stretchability, and uniform and stable toughness. The thickness of the substrate is: 25, 50, 75 μm. With the current automation requirements, longer films are required, and thick films are not desirable, so there are 7, 10, 12, 23, 27, 30, 37 μm series.

(2) Abrasive grains: Al2O3, SiC, and Cr2O3 (grinding head), CeO2, synthetic diamond single crystal, polycrystal, FeO, etc. are mainly used in Japan. The particle size is required to be fine, and the distribution is uniform, which requires strict control of the particle size distribution and no large particles. 3M precision grinding in the United States produces four kinds of abrasive grains: Al2O3, SiC, artificial box stone, CBN. All abrasive grains are finely screened and will not have a rough pattern when used. The products are waterproof, dry or wet.

(3) Binder: mainly a polymer resin and dozens of compound additives. Commonly used are propylene, epoxy, and ethyl urethane. The first two are harder and the latter one is softer. It is generally required to apply twice on the film, the first application is to increase the adhesion of the film.

(4) Coating; mainly using electrostatic method and roll coating method. In the electrostatic method, the binder is phenol. The substrate is a polyester film. The abrasive is A12O3, SiC. The roll coating method mainly uses the printing technology, the abrasive and the binder are mixed and rolled, and the coating thickness is controlled by the roller, that is, adjusting the sound gap of the roller to adjust. There are also mixing methods, sintering methods, electroplating methods, and Ni plating methods.

The heat-resistant temperature of the abrasive film in Japan is the temperature of the polymer binder used, which is about 25 ° C. In the case of grinding, the principle of wet processing is as follows. The coolant is water and oil. Generally, water can meet the requirements (such as tap water). Pure water is used for precision machining, and kerosene is used for grinding aluminum alloy.

Precision grinding systems that use abrasive films will be the trend for future finishing and are more advanced than abrasive belt tools. It can improve production capacity and efficiency, with high qualification rate, good quality, widening production range, and accurate control of the entire grinding process. The re-production rate is low, and employees can get on the job after a little training. It can be said that the fine polishing industry will be the world of abrasive film tools in the future.