Contamination and maintenance of injection molding machine hydraulic system

- Nov 24, 2017-

The quality of injection molding machine hydraulic system depends not only on the rationality of system design and the performance of system components, but also on the pollution prevention and treatment of the system. The pollution of the system directly affects the reliability of the hydraulic system of injection molding machine and the service life of the components.

According to statistics, the domestic and foreign injection molding machine hydraulic system fault about 70% is caused by pollution. The harm of oil pollution to the system is as follows:

1. Pollution wear of components

All kinds of pollutants in oil cause wear of components in various forms, and solid particles enter into the clearance of the moving pair, resulting in cutting wear or fatigue wear on the surface of the parts. Surface erosion of solid particles in high speed liquid flow causes erosion wear. The oxidation products of water and oil in oil are corrosive to the elements. In addition, the air in the oil system causes cavitation, leading to erosion and destruction of the surface of the components.

2. Component blocking and clamping failure

Solid particles block the gap and orifice of the hydraulic valve, causing the spool blocking and clamping, affecting the performance, and even lead to serious accidents.

3, to accelerate the deterioration of the performance of the oil

The energy of water and air in oil is the main condition for the oxidation of oil, and the metal particles in Oil play an important catalytic role in the oxidation of oil. In addition, the water and suspension bubbles in the oil decrease the strength of the oil film between the moving pairs, and reduce the lubricity.

First, kinds of pollutants

Pollutants are the substances that harm the system in the oil system of the injection molding machine. They exist in different forms in the oil, and can be divided into solid pollutants, liquid pollutants and gaseous pollutants according to their physical form.

Solid pollutants can be divided into hard pollutants, including: diamond, cutting, silicon sand, dust, wear metal and metal oxides; soft pollutants are: additives, condensate of water, decomposition of oil and polymer and maintenance of cotton fiber, fiber.

Liquid pollutants usually do not meet the requirements of the system groove oil, water, paint and chlorine and their halide, etc., usually we are difficult to remove, so in the selection of hydraulic oil to choose the system standard hydraulic oil, to avoid some unnecessary faults.

Gaseous pollutants are mainly mixed into the air of the system.

These particles are often so small that can precipitate and suspended in the oil, finally squeezed into the gap of various valves, a reliable injection molding machine hydraulic system, the gap of limited control, importance and accuracy is extremely important.

Two. Sources of pollutants

The sources of pollutants in the system oil are mainly in the following aspects:

1, the external invasion of pollutants: the external invasion of pollutants mainly in the atmosphere of sand or dust, usually through the fuel tank pores, cylinder seal shaft, pump and motor shaft into the system. The main impact is the use of the environment.

2, the internal pollutant pollutant residues elements in processing, assembly and testing, packaging, storage, transportation and installation in the process of course, these processes can not be avoided, but can be reduced to a minimum, some special components in a clean room or clean the environment in the assembly and debugging of.

3, pollutants produced in hydraulic system of injection molding machine: the system in the operation process of the element wear caused by particles, falling down on the casting sand, metal particles off pump, valve and pipe joints, corrosion and exfoliation with its oil oxidation and decomposition of particles and colloidal material to produce more. Serious is the system of pipeline without flushing and some impurities before officially put into operation.

Three. System maintenance

Before a system is put into general to go through the washing, the washing purpose is to remove residual contaminants in the system, scrap metal, fiber core compounds, etc., in the first two hours of work, even if not completely damage the system will cause a series of failures. Therefore, the following steps should be used to clean the oil circuit of the system:

1) clean the tank with an easy dry clean solvent, and then purge the solvent residue with filtered air.

2) cleaning system all the pipeline, in some cases need to pipe and joint impregnation.

3) installed in the pipe oil filter to supply line and pressure line protection valve.

4) a flush plate is installed on the collector to replace the precision valve, such as electrohydraulic servo valve.

5) check all pipe size is correct, the connection is correct.

If the use of electro-hydraulic servo valve system, servo valve plate to make the flushing oil can flow from the oil pipeline to the collector, and return the tank, allowing the oil circulation to flushing the system repeatedly, let the oil filter out solid particles, washing process, every 1 ~ 2 hours to check the oil filter, oil filter to prevent pollutants is blocked, this time not to open the bypass, if found oil filter immediately began to block oil filter.

The cycle of washing is determined by the structure of the system and the degree of system pollution. If there is no or very few foreign contaminants in the filter medium, a new oil filter is installed, the flushing plate is removed, and the valve is installed!

Planned maintenance: establish regular maintenance system, recommend the maintenance system of injection molding machine hydraulic system as follows:

1) check and replace oil filters at most 500 hours or three months.

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

3) check the hydraulic oil is acidified or other pollutants pollution, the smell of hydraulic oil can roughly identify whether deterioration.

4) repair the leak in the system.

5) ensure that no foreign particles enter the tank from the breather cap of the fuel tank, the plug seat of the oil filter, the gasket of the return line, and the other openings of the tank.