There are five major hazards in the temperature of the
injection molding machine : the thermal deformation of the machine, the viscosity of the oil is reduced, the rubber seal is deformed, the oxidation of the oil is accelerated, and the component pressure of the air is also lowered.
One of the hazards: thermal deformation of the machine
The moving parts with different thermal expansion coefficients in the hydraulic components are stuck due to the smaller matching clearance, which causes malfunction and affects the transmission precision of the hydraulic system, resulting in poor working quality of the components.
Hazard 2: Reduce the viscosity of the oil
Excessive temperature rise in the injection molding machine will result in lower viscosity of the oil, increased leakage, and a significant reduction in pump volumetric efficiency and overall system efficiency. As the viscosity of the oil is lowered, the oil film of the moving parts such as the spool is thinned and cut, and the frictional resistance is increased, resulting in an increase in wear.
Hazard 3: Deform the rubber seal
Excessive temperature rise of the injection molding machine will deform the rubber seal, accelerate the aging failure, reduce the sealing performance and service life, and cause leakage.
Hazard 4: Accelerate oil oxidation and deterioration
If the temperature rise of the injection molding machine is too high, it will accelerate the oxidation and deterioration of the oil, precipitate the asphalt material, and reduce the service life of the hydraulic oil. The precipitate blocks the damper orifice and the slit valve port, causing the pressure valve to become stuck and unable to move, the metal pipe to be elongated and bent, or even broken.
Hazard 5: Causes the quality of parts to work poorly
If the temperature rise of the injection molding machine is too high, the working quality of the components will be deteriorated, and the dissolved air in the oil will escape and generate air pockets, resulting in a decrease in the working performance of the hydraulic system. The ideal operating temperature of the hydraulic system should be between 45 and 50 degrees, because the hydraulic system is designed according to the viscosity of a selected pressure oil, but the viscosity will change with the temperature of the oil, which will affect the work in the system. Components such as cylinders, hydraulic valves, etc., reduce control accuracy and response sensitivity, especially for precision injection machines. At the same time, if the temperature is too high, the aging of the sealing member will be accelerated to harden and break. When the temperature is too low, the processing energy consumption is large, and the running speed is lowered. Therefore, it is very necessary to pay close attention to the working temperature of the hydraulic oil. There are many reasons for the high oil temperature, but it is mostly due to the failure of the oil circuit or the failure of the cooling system.
Solution for overheating of injection molding machine:
(1) According to different load requirements, always check and adjust the pressure of the relief valve to make it just right.
(2) Reasonable selection of hydraulic oil, especially oil viscosity, when conditions permit, try to use a lower viscosity to reduce viscosity friction loss.
(3) Improve the lubrication condition of moving parts to reduce friction loss, which is beneficial to reduce working load and reduce heat generation.
(4) Improve the assembly quality and accuracy of the hydraulic components and hydraulic system, strictly control the matching clearance of the fittings and improve the lubrication conditions. The sealing material with low friction coefficient and the improved sealing structure are used to reduce the starting force of the hydraulic cylinder as much as possible to reduce the heat generated by the mechanical friction loss.
(5) Add a cooling device if necessary.
