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When it comes to the mounting or dismounting of large rolling element bearings, flexible induction heaters can save significant time and resources. Ian Pledger of Schaeffler (UK) Ltd explains why this new heating method is the preferred option compared with other more traditional approaches.
The correct mounting and dismounting of rolling element bearings can save companies valuable time and increase the life of the bearings, as well as maximise the availability of critical plant and machinery by avoiding costly breakdowns.
But in order to correctly mount or dismount bearings, it is usually necessary to heat the bearing first. There are a variety of heating methods available to do this, each with its own advantages and disadvantages.
Heating methods include thermal mounting and dismounting tools (i.e. heating plates), induction heating devices, mounting paste and heating rings. Selecting the most appropriate heating method will ensure that the bearings (or similar circular steel components) are mounted and removed easily and quickly, in a safe, reliable manner, without causing any damage to the bearings or surrounding equipment.
When it comes to heating large-sized bearings (1500mm outside diameter and above), there are several options available: using an oil bath, a gas flame burner, or a medium frequency induction heater.
Heating in an Oil Bath
Using an oil bath requires the customer to have a large enough bath for the bearings to be heated in. If such a bath does not exist, one will need to be constructed, which will require welding work, large quantities of steel and 1-2 days of manpower. Hundreds of litres of oil are also required, which must then be disposed of in the appropriate way and which can be expensive.
Heating using Gas Flame Burners
Compared to oil bath heating, using gas flame burners is a much easier method in terms of preparation, as it requires nothing more than a couple of gas cylinders and a burner. However, heating the rolling bearing and the housing may tie up 3-4 people for up to four hours per component.
With gas burners, there is also a risk of local overheating, which can cause changes to the structure of the component being heated. In addition, after heating is completed, the bearing itself may need to be cleaned or the housing painted, as these parts often become discoloured with black soot from the flames.
Induction heating
Induction heating is superior to traditional heating methods, as it is faster, cleaner and more suitable for batch heating. Heat is transferred directly to the workpiece and unlike alternative heating methods, does not need to be transmitted via convection, radiation or thermal conduction. Fixed and mobile induction heaters are available for this.
As induction heating is uniform across the bearings, local overheating is prevented. During the heating process, rolling bearing steels are automatically de-magnetised.
Due to their increased energy efficiency, induction heaters can reduce heating times by up to 50 per cent, keeping maintenance costs to a minimum. Also, as the systems do not require oil, they have the added advantage of being both clean and environmentally friendly.
Flexible Induction Heating
Whilst induction heaters are suitable for many types of rolling element bearings, they are not always effective with large-sized bearings and housings. The availability of an induction heater that is large enough to cope with the job in hand, not only causes problems because of its physical size, but is also likely to cost tens of thousands of pounds
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 6256 KOYO | 280 | 500 | 80 |
| 6056 KOYO | 280 | 420 | 65 |