1) Set target cleanliness level

The manufacturing gap in hydraulic components can be divided into two basic ranges, namely the minimum 5 for high-pressure components μ m. Maximum 25 for lower pressure components μ M. The actual working gap of a component is determined by its type and the working process conditions it has experienced. These gaps help determine the required oil cleanliness for the component. Based on engineering data and on-site experience, recommended pollution levels for pumps, motors, directional valves, pressure control valves, and flow control valves can be selected by referring to relevant design manuals.

The hydraulic system should clearly indicate the target cleanliness level in its engineering documents, taking into account various factors that affect the system, including oil, working and starting temperatures, temporary load rate, the required service life of the system components, and safety issues, before setting this goal. Due to the fact that the actual cleanliness level of the oil varies with the sampling points in the system (i.e. fuel tank, pressure pipe, return pipe, etc.), unless otherwise specified, it is assumed that the target cleanliness level is set for the return pipe and the return pipe upstream of the filter.

2) Turn off the flushing

The most critical time for the lifespan of a hydraulic or lubrication system is the initial running in period. During this period, various components generate a lot of debris and are mixed with debris during the assembly process, which is washed over the entire system by oil. Quickly capture and remove this pollutant from the system while operating without load. The flushing process consists of three steps. Firstly, drive the pollutants out of the dens and transport them to the filters; Secondly, activate the machine to allow oil to flow through all pipelines and components; Thirdly, use high-efficiency filters to capture pollution. It is best to drive out and transport pollutants by using low viscosity fluids that flow at high speeds. Special flushing fluid can be used or system hydraulic oil can be used at high temperatures. In order to flow through all pipelines, all valves should be operated several times. In some cases, it is necessary to bypass the component connection pipeline in order to allow a large flow of oil to flow through the pipeline. Quickly capture debris and flush the system to the required level of contamination. The target cleanliness level for washing should be two ISO codes lower than the target cleanliness level for system operation. When new oil is introduced into a properly flushed system, achieving system balance will take less time.

3) Regularly check the quality of oil products

The performance of oil products can be selected according to specific needs, but strict control must be exercised over the cleanliness and cleanliness of the oil products. When refueling, it is necessary to filter to prevent the invasion of dust and fiber debris. The oil level should be checked frequently. For new machines, the magnetic rods in the hydraulic oil tank, return oil filter, and the magnetic cup of the servo circuit filter should be cleaned frequently. Dust accumulation in the hydraulic cooler should be removed, and the filter element should be replaced. Regular inspection of oil quality mainly includes the following three aspects:

(1) The degree of oxidation of hydraulic oil. During use, hydraulic oil will gradually be oxidized due to temperature changes, oxygen in the air, and sunlight, resulting in changes in its viscosity and other properties. The degree of oxidation is usually judged by the color and odor of hydraulic oil. If the color of the hydraulic oil is black brown and there is a foul odor, it indicates that it has been oxidized. The darker the brown color and the stronger the foul odor, the more severe the oxidation. At this point, a new oil should be replaced.

(2) The degree of moisture in hydraulic oil. If water is mixed in hydraulic oil, it will reduce its lubrication performance and corrode metals. To determine the degree of water mixing in hydraulic oil, it is usually based on the changes in its color and odor. If the color of hydraulic oil is milky white and the odor does not change, it indicates that too much water has been mixed; Additionally, a small amount of hydraulic oil is dropped onto the hot iron plate. If a "beep" sound is emitted, it indicates that there is moisture present. At this point, the oil should be replaced with a new one.

(3) The presence of impurities in hydraulic oil. After working mechanically for a period of time, take a few drops of hydraulic oil and place them in your hand. Twist them with your fingers to see if there are metal particles, or observe if there are small flash points under sunlight. If there are many metal particles or flash points, it indicates that the hydraulic oil contains a lot of mechanical impurities. At this point, the hydraulic oil should be replaced or drained for at least 42 hours of sedimentation, and then filtered before use.