Injection Molding Machine Maintenance and Inspection: Hydraulic, Electrical, and Mechanical Systems

Injection Molding Machine Maintenance and Inspection

Injection molding machines require regular maintenance to operate efficiently and produce consistent quality products. This guide covers the three main maintenance systems and provides detailed inspection schedules.

Part 1: Hydraulic System Maintenance

Hydraulic Oil Management

• Use the hydraulic oil model recommended by the manufacturer with good viscosity, cleanliness, oxidation resistance, and lubricity.
• Regularly test oil condition through appearance test (color, transparency, sediment), drop test (observe oil on filter paper), and finger friction test (degraded oil feels rough).
• Maintain proper oil temperature: 40-50 degrees Celsius during operation.
• Replace hydraulic oil every 5,000 hours or at least once per year.
• Clean the oil tank interior when replacing oil to remove accumulated sludge and impurities.

Component Maintenance

• Regularly clean air filters, oil filters, and the cooler interior.
• Use soft water as cooling water and clean the cooler at least once per year.
• Check oil pipe joints for looseness and aging; tighten or replace as necessary.

Part 2: Electrical System Maintenance

1. Always turn off power before performing any maintenance tasks.
2. Regularly check wire connections for tightness and damage.
3. Clean the motor annually to prevent dust accumulation causing heating problems.
4. Regularly inspect and tighten heating tubes to ensure effective heat transfer.
5. Check electromagnetic contactors for proper operation; replace if overheated or damaged.
6. Check the machine controller for faulty components and ensure proper working conditions.

Part 3: Mechanical System Maintenance

1. Platen Parallelism: Regularly adjust to prevent uneven mold closure and equipment wear.
2. Mold Thickness Adjustment: Regularly inspect and adjust for smooth production.
3. Lubrication Control: Keep all moving parts well-lubricated to prevent wear.
4. Machine Operation Check: Regularly check for abnormalities to prevent vibration.
5. Bearing Inspection: Check for abnormal sounds or temperature rise; replace if necessary.
6. Injection Unit Maintenance: Clean the hopper thoroughly, place a magnet at the inlet to prevent metal impurities, limit screw speed to 40 rpm during initial filling, and apply high-temperature resistant lubricant on thread ends.

Inspection Schedules

Daily

• Electrical: Prevent unnecessary power-on, water ingress; monitor temperatures; replace old relays.
• Hydraulic: Maintain oil temp 30-50 degrees; monitor viscosity; check for leaks; replace oil every 3,000-4,000 hours.
• Clamping: Lubricate hinges; keep tie bars clean; use appropriate pressure.
• Injection: Lubricate guide shafts; use only approved materials; wait for barrel temperature before starting.

Weekly

• Check heaters, oil leaks, lubricator, screws and nuts; clean machine body.

Monthly

• Verify weekly items; check ground wires, terminal screws; check platen for wear; clean filter element.

Quarterly

• Check hydraulic oil quality; verify machine movements; clean filter element; semi-annually clean cooler.

Annual

• Clean motor air intake; check ventilation system; measure insulation resistance.