The performance of a China injection machine can be affected by multiple factors, such as thermal expansion and contraction, gas accumulation, liquid viscosity changes, and mechanical wear. These factors can often lead to unstable pressure during machine operation. Continuous monitoring and timely adjustments can help prevent unnecessary losses.
Causes of Pressure Instability in China Injection Molding Machine
The combined effect of multiple factors, such as thermal expansion and contraction, gas accumulation, liquid viscosity, mechanical wear, etc often causes the unstable pressure of the machine. During the operation of the China injection molding machine, we must always pay attention to the changes of various factors, and make adjustments and repairs in time to prevent unnecessary losses.
Pressure instability is caused by the oil level being too low, air being sucked in or the inlet filter being blocked, causing the oil to gasify under negative pressure.
The China injection molding machine is the main molding equipment that uses plastic molding molds to make plastic products of various shapes from thermoplastics or thermosetting materials.
Its working principle is similar to that of a syringe for injection. It uses the thrust of the screw (or plunger) to inject the plasticized molten state (i.e., viscous flow state) plastic into the closed mold cavity, and obtains the product after solidification and finalization.
Injection molding is a cyclic process, and each cycle mainly includes: quantitative feeding-melting plasticization-pressure injection-mold filling cooling-mold opening and taking out the parts. After taking out the plastic parts, the mold is closed again for the next cycle.
China injection molding machine operation items: molding machine operation items include keyboard operation, electrical control system operation, and hydraulic system operation. They are respectively used to perform injection process actions, feeding actions, injection pressure, injection speed, selection of ejection types, monitoring of the temperature of each section of the barrel, and adjustment of injection pressure and back pressure.
Causes of unstable pressure
1. The oil level is too low, and air is sucked in; or the inlet filter is blocked, causing the oil to gasify under negative pressure, and then be “liquefied” after being pressurized when it leaves the pump, causing the oil pump to malfunction.
2. The overflow valve (pressure controller) fails, or the overflow pipe and the return oil pipe are blocked.
3. There is a problem with the hydraulic system, resulting in excessive pressure.
The weight of the mold of the China injection molding machine is supported by the horizontal template for up and down opening and closing, and there will be no phenomenon similar to the horizontal machine caused by the gravity of the mold, which makes the template unable to open and close. It is conducive to maintaining the accuracy of the machine and mold for a long time.
Five major hazards of excessive temperature rise of the China injection molding machine: thermal deformation of the machine, reduced oil viscosity, deformation of rubber seals, accelerated oxidation and deterioration of the oil, and also reduced the component pressure of the air. The moving parts with different thermal expansion coefficients in the hydraulic components are stuck because of the smaller matching clearance, causing failure of the action, affecting the transmission accuracy of the hydraulic system, and causing the working quality of the parts to deteriorate.
During the molding process of the China injection molding machine, different frequency outputs are made for different pressure flows, and the pressure flow is precisely closed-loop controlled to achieve high-speed response, optimal matching and automatic adjustment of the servo motor to the energy demand of the China injection molding machine.
Notes:
1. Before operating the moulding machine, check whether water or oil is in the electrical control box. If the electrical appliance is damp, do not turn on the machine. Maintenance personnel should blow the electrical parts dry before turning on the machine.
2. Before operating the China injection molding machine, check whether the power supply voltage meets the requirements, which should generally not exceed ±6%.
3. Check whether the emergency stop switch and the front and rear safety door switches are normal. Verify whether the rotation direction of the motor and the oil pump is consistent.
4. Check whether each cooling pipeline is unobstructed for a long distance, and pass cooling water into the cooling water jacket at the oil cooler and the end of the barrel.
5. Before operating the China injection molding machine, check whether there is lubricating oil in each moving part, and add enough lubricating oil.
6. Turn on the electric heating to heat each section of the barrel. When the temperature of each section reaches the requirement, keep it warm for a period to stabilize the machine temperature. The holding time varies according to the requirements of different equipment and plastic raw materials.
FAQ
Lower the melt temperature, increase mold temperature, slow down injection speed, and optimize gate design to help reduce injection pressure without compromising part quality.
Holding pressure minimizes shrinkage, enhances dimensional stability, and reduces sink marks by compensating for material shrinkage as it cools in the mold.
Injection molding pressures typically range from 50 to 200 MPa, depending on material type, part design, and machine capabilities.
Maximum injection pressures can reach up to 250 MPa or more in high-performance machines, tailored for demanding materials or complex part geometries.
