How to Control the Working Temperature of a Medium Frequency Induction Furnace

As a professional manufacturer of induction furnaces, Luoyang Judian has long been committed to helping industrial users achieve safe, efficient, and reliable metal melting operations. Among our product line, the medium frequency induction furnace remains one of our most in-demand solutions due to its high thermal efficiency, fast melting speed, and versatile applications.

One of the most frequently asked questions we receive from new users is:
How do you properly control the working temperature of a medium frequency induction furnace, especially during cold start and initial operation?

This article outlines practical guidance and safety precautions to help operators control temperature effectively and prevent common start-up issues.

Cold Start Procedure for a Medium Frequency Induction Furnace

The cold start process is a critical step that directly affects furnace lining integrity and overall equipment life. Improper handling during this phase may cause cracks in the refractory lining due to thermal shock.

Here are key steps to follow:

1. Allow time for the furnace lining to expand
   Before molten metal contacts the furnace lining, ensure it has been adequately preheated. This prevents damage caused by rapid temperature changes.
2. Use thermocouples for accurate monitoring
   • Deploy 3 to 4 K-type thermocouples.
   • Place them close to the furnace wall and at the bottom.
   • Focus on the core coil zone, where temperature is most critical.
3. Begin with low power and ramp up gradually
   • Start at 20–30% of rated power for the first 15 minutes.
   • This controlled heating helps close any microcracks formed during cooling.
   • After preheating is complete, shift to full power for standard operation.
4. Optional: Add inert gas to reduce thermal gradients
   Introducing gas at the furnace bottom can reduce temperature differences between the upper and lower lining sections, ensuring uniform expansion.
5. Melt the charge quickly after heat preservation
   Once the lining reaches target temperature, begin melting to minimize energy loss and thermal stress.

Standard Startup Procedure (If Furnace Already Warm)

If the furnace is not cold but needs to be restarted, follow this sequence to ensure smooth power delivery:

1. Close the low-voltage switch frame
   Check the three-phase voltage and confirm the ammeter readings are normal.
2. Set the power potentiometer to a low value
   This prevents current spikes during the initial power flow.
3. Activate the IF system step-by-step
   • Press the control power switch.
   • Wait 2–3 seconds, then press the main circuit switch.
   • Finally, press the inverter start button.
4. Verify system status
   Confirm that the DC voltmeter, ammeter, frequency meter, and power meter display normal readings.
5. Increase power slowly
   Adjust the power knob gradually to reach the desired input level.
6. If startup fails
   If the inverter fails to establish intermediate frequency (IF), press the inverter stop button to reset, then restart the inverter.

Final Thoughts

Proper control of working temperature—especially during the cold start phase—is essential to prolonging furnace life, ensuring operator safety, and achieving high melting efficiency.

At Luoyang Judian, we not only manufacture and supply advanced induction furnace systems, but also provide full technical support for installation, operation, and maintenance. With years of industry experience, we help our global customers optimize their smelting processes from day one.

Contact us today to learn more about our medium frequency induction furnace solutions and receive customized guidance for your production needs.