Maintenance of Induction Heating Coils with Magnetic Concentrators
In many applications Fluxtrol concentrators work longer than copper. Factors that can cause the concentrator failure:
- Mechanical damage by the part or during the coil installation
- Material overheating resulting in crumbling. Overheating may be caused by insufficient cooling of the coil, improper design and manufacturing or by concentrator separation from the coil tubing due to cracks in glue
- Electrical break causing shutting off the power supply protection system or arcing and “burning”. Electrical break can happen because of improper coil design, wrong material selection (e.g. using Fluxtrol 50 instead of Ferrotron 559H) or accumulation of metallic particles on the coil surface
Mechanical damage is one of the main factors causing coil failure and proper preventive measures must be taken.
Visual control of Fluxtrol concentrators:
- Check concentrator integrity, attachment (loose parts, cracks in material and glue, mechanical damage) and insulation conditions when applicable
- Periodically clean concentrator from dirt, metallic chips and scale
- Check that water flow through the coil is normal
Dark surface of Fluxtrol material may be due to smoke and quenchant buildup. Gently scratch the surface with knife or other sharp tool. If the cleaned surface has grey metallic color typical for a particular Fluxtrol material, the concentrator is sound and coil may be used further.
Dark and crumbling surface shows that concentrator material was strongly overheated. Factors causing overheating must be corrected and the concentrator replaced. If the coil lifetime is not sufficient, provide additional cooling or change the coil design.
In some applications, especially in installations with tube generators, sparking from a concentrator to the part or fixture may occur. If there is a ground protection, the generator turns OFF quickly however there might be small areas on the concentrator damaged by sparking. Remove damaged volumes with a sharp tool and eliminate a factor that caused sparking (too small gap, metal particles, etc.). Concentrator can continue to work if damage was small.
If there is no ground protection, electric break can be followed by arcing and formation of local conductive metallic zone, which may be heated by eddy currents induced by magnetic field. Degraded concentrator should be removed from the coil. For removing concentrator from the coil copper, it is necessary to heat the coil above the service temperature of adhesive in order to destroy it, usually around 300-350 °C when high temperature epoxy has been used as glue.