Injection Molding Machine Common Faults and Solutions
Injection molding machines combine mechanical, hydraulic, and electrical systems. When faults occur, quick diagnosis is essential to minimize downtime. This reference table covers the most common faults, their causes, and solutions.
1. Motor Does Not Run
- Causes: Power fuse blown; start button poor connection; overload relay tripped; main circuit relay broken.
- Solutions: Replace fuse; inspect, repair, or replace related accessories.
2. Buzzing Sound and No Rotation
- Cause: Missing phase (power supply issue).
- Solution: Check power supply for all three phases.
3. Oil Pump Makes Abnormal Noise
- Causes: Suction side drawing in air; oil filter blocked; wear inside the pump; oil level too low.
- Solutions: Repair suction side joints; clean filter screen; inspect and repair oil pump; refill oil.
4. No Action at All
- Causes: Total pressure valve fault; amplifier board fault; motor/oil pump connecting flange fault; servo valve electromagnetic coil fallen off.
- Solutions: Repair total pressure valve and amplifier board; inspect connector; reinstall electromagnetic coil.
5. Mold Does Not Close
- Causes: Ejection not retracted; safety door not closed properly; manipulator not giving mold-close signal; position ruler data fault; directional valve not acting.
- Solutions: Check ejection retraction status; check safety door circuits and mechanical safety; inspect manipulator position circuit; check position ruler; check valve body for power and stuck phenomena.
6. Mold Does Not Open
- Causes: Directional valve fault; insufficient pressure; toggle mechanical jamming; position ruler fault.
- Solutions: Check valve body; adjust mold opening pressure; inspect toggle arm; inspect position ruler.
7. No Ejection
- Causes: Manipulator giving no ejection signal; mold opening incomplete; solenoid valve fault.
- Solutions: Check manipulator; check if mold opening is complete; inspect solenoid valve.
8. Pressure Does Not Rise or Rises Slowly
- Causes: Pressure adjusting valve not tight enough; air inside hydraulic cylinder; pressure regulating valve fault.
- Solutions: Remove and inspect; exhaust the air; inspect and repair.
9. No Injection
- Causes: Solenoid valve operating poorly; pressure adjusting valve poor; foreign object blocking nozzle; nozzle too cold or barrel temperature low.
- Solutions: Check solenoid valve; check safety valve; check nozzle; check temperatures of all sections.
10. No Material Feeding
- Causes: Solenoid valve poor; back pressure poorly adjusted; barrel temperature incorrect; screw broken or slipping.
- Solutions: Check back pressure valve; check temperature; inspect screw condition.
11. Abnormal Electric Heating
- Causes: Relay fault; heating ring broken; thermocouple broken; wire short circuit or grounding.
- Solutions: Replace damaged accessories; repair wiring.
12. Oil Temperature Too High or Oil Leakage
- Causes: Operating pressure exceeding limits; oil pump wear or oil viscosity too high; insufficient oil volume; cooler blocked; oil cylinder screws loose.
- Solutions: Inspect pump and lower viscosity; add sufficient hydraulic oil; clean cooler; tighten all screws.
13. Directional Valve or Pressure Valve Generating Noise
- Causes: Improper pressure adjustment with spring resonance; valve core stuck; electromagnetic coil aging; poor wiring or insufficient voltage.
- Solutions: Readjust pressure; clean valve core; replace accessories; inspect and repair wiring.
