Understanding and Solving Issues of Inadequate Pressure in an Injection Molding Machine

Injection molding machines are widely used in various manufacturing industries. One common issue that operators may encounter is inadequate pressure. This can severely impact the quality and efficiency of the production process. This article comprehensively explores the reasons behind this issue, and provides solutions to effectively address it.

Common Reasons for Insufficient Pressure in Injection Molding Machines

1. Loose or Poor Contact of the Proportional Valve Solenoid Electrical Socket

The proportional valve is a crucial component of the injection molding machine, which regulates the pressure and flow. Poor contact of the electrical socket can lead to insufficient pressure. This issue can be identified by checking the electrical connection. If the problem persists, the solenoid socket may need to be tightened or replaced.

2. Blockage in the Damping Hole or Stuck Proportional Valve Core

Another common issue is the blockage of the damping hole in the proportional valve or the core being stuck. In such cases, the valve needs to be disassembled, cleaned, and checked for any wear and tear. Regular maintenance and cleaning can prevent such issues and ensure the longevity of the machine.

3. Insufficient Oil Level and Noisy Oil Pump

A low oil level in the hydraulic oil system can result in a lack of pressure. The oil pump makes a lot of noise when the system is low on oil, indicating that it is struggling to function effectively. Adding more hydraulic oil can resolve this issue. Regularly checking and maintaining the oil level is essential to prevent such problems.

4. Foreign Debris or Malfunctioning Valves

Debris stuck inside certain valves or broken internal springs can also cause insufficient pressure. By manually pressing the pin of the electromagnet and checking the valve, any foreign debris or malfunctioning components can be identified and removed. Cleaning and replacing these components can help restore the machine's functionality.

5. Contaminated Hydraulic Oil and Blocked Oil Filters

If the hydraulic oil is not clean and the oil filter is blocked, it can lead to insufficient pressure. Cleaning the oil filter and replacing the hydraulic oil with new, clean oil can resolve this issue. Regular maintenance of the hydraulic system is crucial to ensure that the oil remains clean and free from contaminants.

6. Damaged Oil Pump

In serious cases, the oil pump itself may be damaged. Repairing or replacing the oil pump can solve the issue. This is a more complex process that requires professional expertise.

7. Damaged Sealing Rings in the Oil Cylinder

The sealing rings in the oil cylinder can also be a source of insufficient pressure. If the piston oil seal is damaged, it needs to be replaced. This is another area that often requires professional assistance to ensure proper installation and functionality.

Further Analysis and Troubleshooting

The pressure gauge on the machine is installed between the outlet of the oil pump and the control valve. When the oil pump starts, it hits the oil. After reaching a certain pressure, the oil is discharged back to the oil tank through the pressure relief valve. However, if there is line resistance, the oil can also be returned through the control valve to the tank. This highlights the complexity of diagnosing and solving issues in the hydraulic oil system.

A thorough analysis of the hydraulic system diagram is necessary to identify the exact cause of the problem. In many cases, the proportional valve is worn out or there are foreign objects present. If adjusting the current on the circuit board is ineffective, a proportional valve from another machine can be replaced and tested.

Additional Considerations

1. Low Actual Load: If the actual load is low but products are not fully filled, it indicates that the pressure should be much higher. This issue should be ruled out.
2. Screw Check Ring Failure: If the screw check ring is not properly sealing material, it can be tested by sealing the nozzle with a steel plate or other methods and performing the injection action. If the screw moves forward, it indicates a problem with the ring and it needs to be replaced.
3. Piston Leakage: If leakage from the injection piston is causing the pressure to not rise past 5MPa, the piston oil seal needs to be replaced.

Regular maintenance, thorough analysis, and professional support are key to resolving issues of inadequate pressure in injection molding machines. By understanding the root causes and taking targeted actions, manufacturers can significantly enhance the performance and reliability of their equipment.

Keywords: Injection Molding Pressure, Proportional Valve, Hydraulic Oil System