Electrical System Troubleshooting for Injection Molding

The INOVA 10-inch LED controller on SPV5 machines stores the last 500 alarm events with timestamps, providing a diagnostic trail for intermittent faults. Access the alarm history through the Settings menu by pressing the alarm log icon. Common error categories include E1xx series (temperature faults), E2xx series (hydraulic pressure faults), E3xx series (position and speed faults), and E4xx series (safety circuit faults). For temperature errors, E101 indicates heater zone open circuit—measure heater resistance at the terminal block, which should read 8-25 ohms depending on the zone wattage (1.5-8kW per zone). E102 indicates thermocouple fault—check the J-type thermocouple wiring polarity and terminal integrity. For hydraulic errors, E201 indicates system pressure below setpoint—verify pump operation and relief valve setting at 17.5 MPa. E203 indicates accumulator charge failure—check the nitrogen pre-charge and solenoid valve function. When the controller screen freezes or displays garbled text, perform a power cycle by turning off the main disconnect, waiting 30 seconds, and restarting. If the issue persists, the controller backup battery (CR2032 lithium cell, 3-5 year life) may need replacement to preserve SRAM parameter storage.

The barrel heating system on SPV5 machines consists of 6-8 independently controlled zones with total power from 22.5kW (HMD 270M8-SPV) to 45kW (HMD 600M8-SPV). Each zone uses a solid-state relay (SSR) to switch the heater band circuit. When a zone fails to heat, first check the SSR output by measuring AC voltage across the heater terminals with the zone calling for heat—you should read 220V AC. If no voltage is present with the control signal active, the SSR has failed (most common heater circuit fault). SSR failure modes include open circuit (zone does not heat) and short circuit (zone heats continuously and overtemperatures). Replace SSRs preemptively every 3-4 years. Check heater band resistance: a 5kW heater on 220V should measure approximately 9.7 ohms; deviation exceeding 15% indicates internal element degradation. Thermocouple faults cause temperature oscillation or runaway. Verify thermocouple response by heating the tip with a heat gun and observing the controller reading—it should respond within 3 seconds and show smooth temperature increase. Loose thermocouple mounting causes 5-15°C reading errors due to poor thermal contact. For hot runner zone troubleshooting, verify that all hot runner heater resistance values are within the mold manufacturer's specification, typically 5-50 ohms per zone.

SPV5 safety circuits use a dual-channel architecture where two independent switch contacts must close simultaneously to enable machine operation. When the machine displays a safety fault and refuses to cycle, systematically check each interlock point. The front safety gate uses two proximity switches—verify both switch LED indicators illuminate when the gate is fully closed. Measure the switch output voltage (24V DC present when actuated). Rear gate interlocks use the same dual-switch configuration. The purge guard interlock prevents screw rotation when the guard is open; verify the limit switch actuator aligns with the switch roller within the specified 2-3mm engagement depth. Emergency stop circuits on SPV5 machines use NC (normally closed) contacts wired in series—pressing any of the 4 E-stop buttons breaks the safety relay circuit. After releasing an E-stop, the machine requires a deliberate reset sequence: release the E-stop button, then press the safety reset button on the controller. If the safety relay does not reset, one of the E-stop switches may have a welded contact (stuck closed when pressed)—test each switch with a multimeter in ohms mode. Wiring faults in the safety circuit require immediate repair by qualified electricians to maintain CE compliance.

Weekly checks include verifying all heater zone temperatures are within plus or minus 3°C of setpoint, checking the INOVA controller alarm log for any new entries, and verifying that all status indicator lights on the servo drives show normal operation (steady green). Monthly tasks include thermal scanning of the main electrical cabinet with an infrared thermometer or camera to identify hotspots at terminal connections—any point exceeding 70°C requires immediate retorquing or replacement. Inspect all cable glands for tightness and check flexible conduit connections at moving parts like the injection carriage. Quarterly maintenance includes measuring motor insulation resistance on the pump motors (minimum 10 megaohms when cold), testing all SSR outputs, and verifying thermocouple calibration against a reference thermometer. Every 6 months, clean the electrical cabinet air filters and check the cabinet cooling fan operation—internal cabinet temperature should not exceed 45°C. Annually during the overhaul, retorque all power terminals, test the residual current device (RCD/GFCI), verify the earth continuity of all exposed metalwork, and update the electrical schematic if any modifications were made during the year. Store a copy of the complete electrical schematic inside the cabinet door.