What is induction heating?
Induction heating is a contactless method of heating metal. An alternating magnetic field induces currents inside the metal itself, and the metal becomes its own heat source. Nothing touches the workpiece and there is no flame.
For industrial work this matters in three ways: the heat starts deep inside the part rather than on its surface, it can be controlled precisely, and it removes the hazards that come with an open flame.
Alesco builds portable induction heaters in Sweden, dedicated exclusively to induction heating. Our machines are used to release seized joints, straighten heat-distorted steel, and pre- and post-heat welded parts in production.
How does induction heating work?
There is a lot of talk about the power rating of an induction heater. But power is only one of three parameters that decide the result. The other two are the surface across which that power is delivered, and the frequency.
Power density – power per unit area – is the ratio that actually matters, and the inductor itself is decisive in achieving a high one. This is the area where Alesco leads.
Frequency is always a compromise. The lower the frequency, the deeper the magnetic penetration into the material. Alesco’s three-phase machines run at a fixed 15–18 kHz depending on model, which creates heat deep inside the material. In most industrial applications, that is exactly what you want.
Heating at higher frequencies produces surface heat instead, with a risk of overheating and damaging the surface of the part.
Induction heating versus an open flame
Induction differs from flame heating in a fundamental way: the heat appears immediately, deep in the part being heated. This creates an instant temperature difference between the components of a joint. The difference causes movement, breaks the bond, and reduces the torque needed to release it.
It is also a gentler process. Because heat-sensitive parts nearby stay cool, there is often no need to dismantle them first.
Replace the open flame
- Control the heating process more precisely
- Achieve greater part expansion through penetrating heat
- Save time by leaving heat-sensitive components in place
- Heat without direct contact
- Heat all metals in a controlled manner, including non-magnetic ones such as copper, aluminium and stainless steel
A safer working environment
- Minimal fumes during heating, including on painted parts
- Potential to lower insurance costs by removing the risks associated with gas
- A more ergonomic way to work
- No need for additional protective equipment
- Shoulder, back and crush injuries can be avoided by letting the heat do the work
Where induction heating is used
Induction heating is used wherever metal needs to be heated quickly, precisely and without a flame.
Vehicle workshops and heavy vehicles. Releasing seized nuts, bolts and bearings without a flame, on vehicles where fuel lines, wiring and paint make open-flame heating a risk.
Manufacturing and welding. Pre- and post-heating of welded parts to control cooling rates and reduce residual stress.
Heat straightening. Correcting distortion in steel structures with controlled, localised heat.
Shipyards and marine. Work in confined spaces where gas cylinders are impractical or prohibited.
Forging and smithing. Bringing steel to working temperature quickly and repeatably, without a gas forge.
Maintenance and heavy industry. Shrink-fitting, bearing removal, and any assembly work where components must be expanded rather than forced.
Frequently asked questions
What metals can be heated by induction?
All metals. Magnetic metals such as steel and iron heat fastest, but non-magnetic metals including copper, aluminium and stainless steel can also be heated in a controlled way.
How hot does an induction heater get?
Temperature depends on the material, the inductor and the time applied rather than on a fixed maximum. In practice a seized bolt reaches release temperature in seconds, and steel can be taken to forging temperature.
Is induction heating safer than a gas torch?
Yes, in several respects. There is no open flame, no gas cylinder to store or transport, and far fewer fumes when heating painted or coated parts. It also removes the fire risk in confined spaces.
Does induction heating damage nearby components?
The heat is generated inside the metal being targeted, so surrounding heat-sensitive parts are far less affected than with a flame. This often removes the need to dismantle before heating.
What is the difference between induction heating and conduction?
Conduction transfers heat from an external source into the part by contact. Induction generates the heat inside the part itself, using a magnetic field, with nothing touching the surface.
Why does frequency matter in induction heating?
Lower frequencies penetrate deeper into the material, producing heat throughout the part. Higher frequencies concentrate heat at the surface, which risks overheating and surface damage.
Designed to make you safe
Designing safe machines that help you create a safe working environment is a core focus at Alesco. Our portable induction heaters complies with 2013/35/EU, the European directive regarding health and safety in exposure to magnetic fields. There is also built-in overheating protection and short circuit protection.
See our induction heaters
Alesco builds portable induction heaters for professional and industrial use.
- Induction heaters – the full range, from portable single-phase units to three-phase machines
- Heating tips and inductors – the inductor determines power density, and the right one matters
- Parts and accessories – hose packages, spare parts and accessories by model
- Service and support – manuals, support and service partners
Photos and videos throughout the site show how an induction heater performs in practice.