Analysis of Five Major Causes of Speed Reduction in Five-Star Hydraulic Motors of Injection Molding Machines

Analysis of Five Major Causes of Speed Reduction in Five-Star Hydraulic Motors of Injection Molding Machines

The five-star hydraulic motor (five-star motor) is the core driving component in injection molding machines, and its rotational stability directly affects production efficiency. Based on years of industry experience and failure case studies, Prins Hydraulics has identified the following five common causes and corresponding solutions to help quickly diagnose issues and optimize equipment performance.

1. Oil Supply Pump Damage: Overheating and Noise

Symptoms: Abnormal pump overheating accompanied by noise, resulting in insufficient hydraulic oil flow.
Root Causes:

• Pump wear or internal leakage, reducing output flow and pressure.

• Contaminated hydraulic oil or abnormal viscosity, increasing friction and temperature rise.
  Solutions:

• Inspect and replace worn pump components; prioritize high-efficiency pump models compatible with five-star motors.

• Regularly replace hydraulic oil and clean tank filters to ensure oil cleanliness meets ISO 18/15 or higher standards.

2. Control Valve Malfunction: Blockage in Oil Supply/Return System

Symptoms: Stuck control valves or restricted oil flow, causing localized overheating and motor speed fluctuations.
Root Causes:

• Valve spool sticking or debris blockage, obstructing oil flow.

• Valve seal failure, leading to increased internal leakage and reduced system pressure.
  Solutions:

• Disassemble and clean the valve body; use ultrasonic cleaning to remove stubborn sludge.

• Replace high-temperature-resistant seals to optimize compatibility between the valve and five-star motor.

3. Safety Valve Anomalies: Abnormal Noise and Overheating

Symptoms: Frequent safety valve activation with unusual noise and localized high temperatures.
Root Causes:

• Excessive system pressure settings or failed safety valve springs, causing continuous pressure relief.

• Air entrapment or contamination in the oil, resulting in valve spool vibration and abnormal wear.
  Solutions:

• Calibrate system pressure to the motor’s rated value (refer to equipment manual).

• Install defoaming filters and purge air from oil circuits to reduce cavitation risks.

4. Flow Distribution Valve Leakage: Overheated Valve Chamber

Symptoms: Excessive leakage in the flow distribution valve, with a significant rise in valve surface temperature.
Root Causes:

• Aging or worn seals in the rotary valve, worsening internal leakage.

• High oil temperature reducing viscosity and enlarging leakage gaps.
  Solutions:

• Use fluororubber or polyurethane seals to improve high-temperature resistance.

• Install cooling systems to maintain oil temperature below 50°C.

5. Crankcase Leakage: Abnormal Oil Level and Over-Discharge

Symptoms: Excessive crankcase leakage, elevated oil level, and reduced motor torque output.
Root Causes:

• Worn crankshaft oil seals or excessive bearing clearance, causing external leakage.

• Poorly designed return oil pipelines, delaying oil reflux.
  Solutions:

• Replace crankshaft seals with high-precision models; inspect bearing wear regularly.

• Optimize return pipeline slope and diameter to minimize flow resistance.

Preventive Maintenance Recommendations

1. Monitor Oil Condition: Test viscosity, water content, and contamination levels every 500 hours.

2. Seal Management: Inspect motor seals quarterly and replace aging components proactively.

3. Load Optimization: Avoid overload operation; upgrade motor power if necessary.

By systematically addressing these issues, the operational efficiency and service life of five-star hydraulic motors can be significantly enhanced. For professional technical support, contact the Prins Hydraulics team for tailored solutions!

Note: This translation emphasizes clarity and technical accuracy while omitting internal reference codes for streamlined readability.