Resolving Coil-Related Induction Heating Issues An introductory guide to some common problems in the induction heating manufacturing process

Problems with your induction heating application could be coil-related.

The induction coil is the energy transmitter for the induction power supply – radio frequency (RF) generated in the coil creates a magnetic field that then gets induced into the work piece, heating it up.

An issue with the coil could compromise your application and your entire manufacturing process. The wrong coil design or a worn/defective coil could result in various problems, including:

  • Under heated parts
  • Overheated parts
  • Inconsistent heating
  • Shorting
  • Damage to parts
  • Coil overheating
  • Induction heating power supply tuning issues

These application notes will address some of these issues, what to look for, and how to possibly resolve them.

Problem: Under Heating

Your parts are under heated. No fault errors are indicated on the power supply.

Check for:

  • Water clogs
  • Insulation wearing or burning (internally and/or externally)
  • Coil bent out-of-shape
  • Wrong coil design for your application/material
  • Coil too far from work piece

Most common issue:

Bad water

Water clogs or problem water/water flow. If you have water-cooled coils that are hooked up to your public water supply, there could be particulate matter or other contaminates causing poor water flow or clogs. Water suppliers in the U.S. must supply an annual water quality report to their customers - you should be able to find yours on-line.

Try First:

Flush the coil with clean distilled water. Contact your manufacturer for the best type of water to use or give Inductronix a call at 800-956-3941 for a free technical consultation.

Problem: Part Overheating

Your parts are getting too hot. No errors noted on power supply.

Check for:

  • Wrong coil or design for your material/application
  • Power supply not tuned properly for your material/application
  • Coil too close to work piece

Most common issue:

Having too many coil turns may result in exceeding the required heat length for your application

Wrong coil design. Some induction power supplies’ tuning is based on the coil being used, i.e. number of turns, the coil ID and the coil shape/coil turns, i.e. number of wraps.

The coil ID might be too close to the work piece being heated.

The best solution for your application can be difficult to identify - contact Inductronix at 1-800-956-3941 for a free technical consultation.

Problem: Coil Shorting

Your parts not getting heated. Power supply should trip with a short circuit or high-frequency trip error.

Check for:

  • Coil insulation wear or burning
  • Incorrect air gap between the coil and the part
  • Insufficient insulation
  • Extraneous debris interference
  • Coil windings too close - inter-coil arcing
  • Mistuning - some induction power supplies' output tuning is dependent on the coil winding turns, i.e. wraps, and/or coil ID with respect to the work piece being heated
  • The induction power supply is not tuned correctly for the coil being used

Most common issue:

"Weather and Climate Meet on NPP Satellite" courtesy of and copyright (c) NASA Earth Observatory licensed under CC by 2.0

Incorrect air gap. This can be difficult to gauge – it’s best to contact your supplier’s technical support for assistance or call Inductronix at 800-956-3941 for a free technical consultation.

Try first:

Wrapping the coil with glass tape or coating the coil with a high-temperature-resistant material.

For coil tuning problems: Contact your supplier to make sure that the selected coil is suitable for your induction power supply or give Inductronix a call at 800-956-3941 for a free technical consultation.

Problem: Inconsistent Heating

Your parts do not get heated consistently

Check for:

  • Coil warping
  • Inconsistent air gap between part and coil
  • Insulation wear
  • Wrong/insufficient coil design for application
  • Not enough turns on the coil limiting the heat length

Most common issue:

Induction coil design - make sure your coil has sufficient turns to generate enough heat length for your application

Insufficient design for the application. One customer's issue was resolved by rotating the part while it was in the coil. Another customer's issue was resolved by using ferrites to concentrate heat in the desired places. Another customer's issue was resolved by using a plate concentrator coil

The best solution for your particular application can be difficult to identify - contact Inductronix for a free technical consultation.

Problem: Mechanical Damage to Part

Your parts have physical damage - are discolored or burned

Check for:

  • Improper air gap between coil and part - part is too close to coil
  • Insufficient coil insulation or insulation wear
  • Extraneous debris interference
  • Coil damaged (cracked, burned)

Most common issue:

MIND THE GAP - Epping [2/3] by Christopher_Brown licensed under CC by 2.0

Incorrect air gap. This can be difficult to gauge - contact your induction power supply manufacturer or give Inductronix a call at 800-956-3941 for a free technical consultation.

Problem: Coil Overheating

Your coil is overheating

Check for:

  • Coil water flow. If the coil’s wall tubing is too small it may restrict sufficient water flow through the coil.
  • Water Clogging. Check for any debris that might have built up inside the coil's copper tubing.
  • Insufficient cooling system. Your water cooling system may not be strong enough to provide the flow and PSI needed to cool down the coil sufficiently.

Most common issue:

Make sure your tubing is sufficiently sized

Tubing is too small, restricting water flow.

Try first:

Contact your induction power supply manufacturer for the correct tubing for your application or contact Inductronix at 800-956-3941 for a free technical consultation.

Conclusion

The coil is a major component of your induction power supply, and a problem with the coil can lead to problems in your manufacturing process, resulting in a waste of time, money and material.

A correctly designed, well-maintained and properly used coil could go a long way toward resolving application and production issues.

Give Inductronix a call at 800-956-3941 for a free technical analysis of your particular situation. With a combined 100+ years of induction experience, we're confident we can address your specific application issues and requirements.

Credits:

Created with images by Jemzo - "pollution environment water" • NASA Earth Observatory - "Weather and Climate Meet on NPP Satellite" • christopher_brown - "MIND THE GAP - Epping [2/3]" • LoggaWiggler - "pressure water line pipeline tube"

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