Induction heating loosens frozen fasteners

The induction-heating technique saves technicians time and money during the crucial-but-challenging task of loosening frozen fasteners. Here's how it works.

An induction heater is an electrical device that applies highly concentrated heat onto a stuck or rusted fastener. The proper amount of heat expands a frozen nut, breaking the corrosive bond between it and a bolt or stud.

Experience shows that induction heating loosens frozen fasteners more neatly and efficiently than a traditional oxyacetylene torch does. And unlike a common torch, this technique doesn't burn any materials near the frozen fastener.

The most-popular tool of this type is the Mini-Ductor from Induction Innovations.

Sources who have used this induction heater extensively sing its praises, calling it an essential tool. Although many service personnel already are aware of it, others I encounter are not.

This tool features interchangeable heating elements called "work coils" that apply heat directly to the frozen fastener. Changing from one shape or size work coil to another only takes a moment; it requires no tools.

The selection of work coils within the Mini-Ductor tool kit enables a tech to apply heat efficiently to a wide range of fasteners, fittings and bearings.

I have used these work coils on strut and shock-absorber hardware, exhaust nuts, brake-line fittings, oxygen sensors and wheel nuts.

The induction-heating technique eliminates the potential fire hazard of the cutting torch's open flame.

What's more, it doesn't harm adjacent parts or materials the way a cutting torch does. That's because induction heating method heats only electrically conductive metals such as iron and steel.

So this method won't harm rubber, plastic and fabric materials near the frozen fastener.

Have you spent any time wielding a torch or watching one of your techs use one? If so, then you appreciate how difficult it can be to heat a frozen fastener without damaging anything near it. (A tech may even have recruited you to play fireman with a moistened shop towel.)

Another disadvantage of a traditional torch is its tendency to heat both a frozen nut and its "companion" bolt or stud. Users often aggravate this condition by heating the parts up to a bright red color.

An engineer explained to me that the key is heating the nut itself until it's 200 to 300 degrees hotter than the bolt or stud.

Usually, this is enough to break the corrosive bond between nut and bolt. He said the inductive-heating technique simply excels at focusing heat on the nut itself.

I haven't had to heat anything cherry red with the Mini-Ductor. Instead, I apply heat to it for 10 seconds or so and then try to loosen the nut.

You may be surprised how little heat it really takes to do the job — when that heat is concentrated in the right place.