The main function of the hydraulic oil filter is to filter oil, and various impurities inevitably appear in the hydraulic system. The main sources are: mechanical impurities remaining in the hydraulic system after cleaning, such as scale, casting sand, welding slag, iron filings, paint, paint skin and cotton yarn scraps, etc. Dust that enters the dust ring, etc., impurities generated during the working process, such as fragments formed by the hydraulic action of the seal, metal powder generated by the relative wear of the movement, colloid, asphaltene, carbon residue, etc. generated by the oxidation of the oil. .

After the impurities are mixed into the hydraulic oil, with the circulation of the hydraulic oil, they will play a destructive role everywhere, seriously affecting the normal operation of the hydraulic system, such as making the small gap between the relative moving parts in the hydraulic components and the throttle holes and gaps stuck. Dead or blocked; destroy the oil film between relative moving parts, scratch the surface of the gap, increase internal leakage, reduce efficiency, increase heat generation, intensify the chemical action of the oil, and deteriorate the oil. According to production statistics, more than 75% of the failures in the hydraulic system are caused by impurities in the hydraulic oil. Therefore, it is very important to maintain the cleanliness of the oil and prevent the pollution of the oil.

Generally, pollutants with a particle size below 10 μm have little effect on the pump, but those with a particle size greater than 10 μm, especially those above 40 μm, have a significant impact on the service life of the pump. The solid pollution particles in the hydraulic oil can easily aggravate the surface wear of the relative moving parts in the pump, so it is necessary to install an oil filter to reduce the degree of oil pollution. Filtration accuracy requirements: 10-15 μm for axial piston pumps, 25 μm for vane pumps, and 40 μm for gear pumps. The pollution wear of the pump can be controlled within the allowable range. High-precision oil filters are increasingly used, which can greatly extend the service life of hydraulic pumps.