Pollution Causes and Maintenance of Hydraulic System of Injection Molding Machine

Quality of hydraulic system of injection molding machine not only depends on rationality of system design and performance of system components, but also due to pollution prevention and treatment of system, pollution of system directly affects reliability of hydraulic system of injection molding machine and use of components life.

Hydraulic System of Injection Molding Machine 

According to statistics, about 70% of hydraulic system failures of injection molding machines at home and abroad are caused by pollution. Main hazards of oil pollution to system are as follows:

1. Component blockage and clamping failure

Solid particles block gaps and orifices of hydraulic valve, causing blockage and clamping of valve core, affecting working performance, and even causing serious accidents.

2.Contamination and wear of components

Various pollutants in oil cause various forms of wear of components, solid particles enter gap of moving pair, causing cutting or fatigue wear on the surface of part. Impact of solid particles in high-speed liquid flow on the surface of component causes erosion and wear.

Water in oil, oxidation and deterioration products of oil have a corrosive effect on components. In addition, air in oil of system causes cavitation, which leads to erosion and damage to surface of components. 

3. Accelerate deterioration of oil performance

Water and air in oil are main conditions for oil oxidation due to their thermal energy. Metal particles in oil play an important role in oxidation of oil. In addition, water and suspended bubbles in oil significantly reduce strength of oil film between movement pairs and reduce lubrication performance.

Types of pollutants

Pollutants are substances that are harmful to system in oil of plastic injection molding machine hydraulic system. They exist in different forms in oil. According to their physical forms, they can be divided into solid pollutants, liquid pollutants, and gaseous pollutants.

Solid pollutants can be divided into hard pollutants, including: diamond, cutting, silica sand, dust, wear metals and metal oxides; soft pollutants include: additives, water condensate, oil decomposition products and polymers, cotton threads and fibers brought in during maintenance.

Liquid contaminants are usually grooving oil, water, paint, chlorine and its halides that do not meet system requirements, which are usually difficult to remove. Therefore, when selecting hydraulic oil, choose hydraulic oil that meets system standards to avoid unnecessary failure.

Gaseous pollutants are mainly air mixed into system:

These particles are often so small that they cannot settle down and are suspended in the oil, are finally squeezed into gaps of various valves. For a reliable injection molding machine hydraulic system, these gaps are extremely important to achieve limited control, importance and accuracy.