Introduction to Induction Furnaces and Key Maintenance Considerations

Induction furnaces are widely used in metal smelting and heat treatment processes due to their high efficiency, precise temperature control, and environmental friendliness. However, to ensure their optimal performance and longevity, regular maintenance is crucial. Below are eight essential points to consider for the maintenance of intermediate frequency induction furnaces, along with specific inspection steps for daily, weekly, and semi-monthly checks.

Daily and Periodic Inspection Steps

1. Regular Performance Checks: Conduct a shutdown inspection every week or half a month to assess the overall performance of the machine. This helps in timely identifying any equipment issues. The following steps outline daily and periodic inspection procedures:

Daily Operational Best Practices

2. Optimal Machine Usage:
   • (1) Temperature Monitoring: Utilize a temperature measuring gun to monitor the temperatures of the SCR (Silicon Controlled Rectifier), resistance-capacitance protection resistors, and voltage equating resistors. Temperature measurements should be taken at three stages: 5-10 minutes after running the first furnace of molten steel at about one-third power, when the furnace is nearly full, and at the end of the day's last furnace at full power. Record these measurements to promptly identify and resolve any issues.
   • (2) Cable Screw Inspection: Check daily for loose screws on the cables.
   • (3) Water Pump Verification: Before starting the machine each day, confirm that both the power supply water pump and the furnace body water pump are on. Ensure the water pressure is between 1.5 to 1.7 kg in the power supply cabinet and 1.5 to 2 kg in the furnace body.
   • (4) Cleanliness Around Furnace Body: Keep the area near the furnace body's water cable clean and free from iron filings and metal objects.
3. Pre-Operation Water Pump Check: Open the water pump 10 minutes in advance before running the equipment to observe for any water leakage or seepage. Address any issues immediately to prevent production disruptions.

Temperature and Resistance Monitoring

4. SCR Temperature Anomalies: If the machine detects an abnormal SCR temperature, immediately investigate the cause. Check if the water pipe is folded, causing insufficient water flow and heating, or if there is dirt clogging inside the SCR tube sleeve.

5. Resistance-Capacitance Protection Resistance: If the resistance temperature of the rectifier's resistance-capacitance protection differs significantly from other resistors, check for capacitor open circuits or damaged resistances. Generally, the reactor will emit a buzz and exhibit slight jitter during startup if there are issues.

Weekly and Semi-Monthly Maintenance Checks

6. Comprehensive Maintenance Checks:
   • (1) Line Groove Inspection: During weekly or semi-monthly checks, ensure there are no falling line grooves above the inverter resistance-capacitance protection to prevent short circuits and KK tube burnout. If found, secure them immediately with tie belts.
   • (2) Tightening Screws and Water Clips: Tighten all equipment screws and water clips weekly to prevent damage from falling or loosening.
   • (3) Hydraulic Oil Level: Observe the hydraulic oil level weekly, maintaining it at least at 80% capacity.
   • (4) Water Quality and Nozzle Condition: For areas with lower water quality, regularly inspect the medium frequency power supply cabinet for rotting water nozzles. If severe, install a water dispenser for timely replacement. Never weld a water nozzle back onto the machine after removal, as this can seriously affect production schedules. Generally, replace the water dispenser every three months for open waterway systems and every six months to a year for fully closed systems.

Pipe Sleeve Cleaning and Hydraulic Maintenance

7. Pipe Sleeve Cleaning: Use 20% diluted hydrochloric acid to circulate in the pipe sleeve for 10-15 minutes for cleaning. After washing, rinse with 100% clear water and dry with compressed air to prevent hydrochloric acid from corroding the tube sleeve.

8. Hydraulic Maintenance Points:

   • Pay attention to the cleanliness and quantity of hydraulic oil. Replace the hydraulic oil every six months and clean the filters monthly. Note that there are two filters in the hydraulic station; ensure they are not operating at the bottom of the station. Place them on a shelf within the hydraulic station to prevent iron filings from entering the hydraulic pump and causing damage.

By adhering to these maintenance practices, operators can ensure the efficient and reliable operation of intermediate frequency induction furnaces, extending their service life and minimizing production downtime.

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