The harm of oil pollution to the system is as follows:

Solid particles enter the clearance of the moving pair, resulting in cutting wear or fatigue wear on the surface of the parts. The impact of solid particles on the surface of components in high speed liquid flow causes erosion wear. The water in the oil and the products oxidized by the oil have corrosive effects on the components.

Solid particles block the gap and the orifice of the hydraulic valve, causing the valve core to block and clamp, affecting the working performance, and even leading to serious accidents.

3. The water and air in the oil are oxidized at high temperature, while the metal particles in the oil play an important catalytic role in the oxidation of the oil, and the water and suspended bubbles in the oil significantly reduce the strength of the oil film between the moving pairs, Reduce the lubrication performance.

A, the types of pollutants

Solid pollutants: can be divided into hard pollutants, there are: diamond, cutting, silica sand, dust, wear metal and metal oxides; Soft pollutants are: additives, water condensates, oil decomposition and polymers and maintenance of cotton silk, fiber.

Liquid pollutants: usually does not meet the requirements of the system cutting tank oil, water, paint and chlorine and its halides, etc., is usually difficult to remove, so in the selection of hydraulic oil to choose the hydraulic oil in line with the system standards, to avoid some unnecessary failures.

Gaseous pollutants: is mainly mixed into the system of air. These particles are too small to precipitate down, suspended in the oil, and finally squeezed into the gaps of various valves. For a reliable injection molding machine hydraulic system, the cleanliness of these gaps is extremely important to achieve limited control, importance and accuracy.

Two, the source of pollutants

The source of pollutants in the oil of the system mainly has the following aspects:

external intrusion of pollutants: is closely related to the use of the environment, mainly gravel or dust in the atmosphere, usually through the tank porosity, cylinder seal shaft, pump and motor shaft intrusion system.

Internal pollutants : components in the processing, assembly, debugging, packaging, storage, transportation and installation and other links of residual pollutants, some special components in the assembly and debugging need to be carried out in the environment of clean room or clean table, in order to improve.

Pollutants produced by the hydraulic system of injection molding machine: System in the process of operation due to the wear and tear of the components caused by the particles, the sand falling off the casting, the metal particles falling off the pump, the valve and the joint, the rust in the pipeline to its oil oxidation and decomposition of the particles and glue, more serious is the system pipeline before the formal operation without washing and a large number of impurities.

Three, the maintenance of the system

A system in the formal input before generally have to be washed, remove the residual pollutants in the system, metal chips, fiber compounds, core, etc., it is recommended to clean the system oil circuit according to the following steps:

1) Clean the tank with a kind of easy to dry cleaning solvent, and then remove the solvent residue with filtered air.

2) Clean all the pipes of the system, in some cases need to impregnate the pipes and joints.

3) Install oil filter in the pipeline to protect the oil supply pipeline and pressure pipeline of the valve.

4) Install a flushing plate in the collector to replace precision valves, such as electro-hydraulic servo valves, etc.

5) Check that all lines are properly sized and properly connected.

If the electro-hydraulic servo valve is used in the system, the washing plate of the servo valve should make the oil flow from the oil supply pipeline to the collector, and directly return to the tank, so that the oil can be repeatedly circulated to flush the system, so that the oil filter can filter out the solid particles, during the washing process, every 1 to 2 hours to check the oil filter to prevent the oil filter from being blocked by pollutants, At this time, do not open the bypass, if it is found that the oil filter begins to block, immediately change the oil filter.

Flushing cycle is determined by the structure of the system and the degree of system pollution, if the sample of the filter medium has no or few foreign pollutants, then install the new oil filter, remove the washing plate, install the valve to work!

2) regularly flush the imported oil filter of the oil pump.

3) Check the hydraulic oil is polluted, the smell of hydraulic oil can roughly identify whether the deterioration.

4) Repair the leakage in the system.

5) Ensure that no foreign particles enter the tank through the vent cap of the tank, the plug seat of the oil filter, the sealing gasket of the return line, and other openings of the tank.

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