In order to heat a bearing for proper bearing installation, you can use multiple methods. In this case, I will compare using an Oven to using an Induction Heater.
Ovens come in different shapes and sizes but in essence, it is what we know an oven to be, you will place a bearing into the oven and bake it (heat it).
Using proper protection is essential in using an oven as not only the inside of the oven will be very hot but in all likelihood the outside as well and since some ovens can be quite large, regular gloves will not be sufficient. It is also very important that the surface onto which the bearing will be placed in the oven is clean so as to not contaminate the bearing that will be heated.
Monitoring of the temperature is imperative to make sure that you do not overheat the bearing. Most ovens have temperature controls that allow you to do that. It is not necessary to wait for the oven to reach the desired temperature in order to place the bearing or bearings in it. It is important to make sure that not only has the oven reach the desired temperature but also the bearing, it does take the bearing some time to be at the same temperature as the oven, using an external device might be necessary. Unlike the hotplate with an oven the bearings do not have to be turned over to heat both sides, so the heating should be even across the bearing.
Once the bearing is ready, make sure to wear your Personal Protective Equipment (PPE) while handling the bearing and being near the hot oven.
Sealed or pre-lubricated bearings should not be heated in an oven as both the seal and the lubricant may be compromised.
In comparison, if an Induction Heater is used, make sure that you are using the correct Induction Heater based on the weight of the bearing, and also make sure that you are using the largest possible yoke (crossbar) for the ID of the bearing being heated. Also, make sure gloves are used to handle the bearing after the heating cycle is completed.
Place the bearing with either the horizontal yoke (crossbar) going through the bore or one of the vertical posts, going through the bore. Set the desired temperature on the Induction Heater, using the control panel, make sure to place the temperature probe on the I.D. (inner bore diameter) of the bearing, not on the O.D. (outer bore diameter)*. Once you have selected the temperature to which you wish to heat the bearing (not to exceed 250˚ F) and press Start to begin the heating cycle. Once the heating cycle is completed and the bearing has automatically been demagnetized **, place the bearing on the shaft. (Remember to never spin the bearing while hot).
Comparison between an oven and induction heater when heating bearings
While ovens can be used relatively acceptably for batch heating of small bearings, their use for heating larger bearings generally will be inefficient and time-consuming, as well as adding to potential handling hazards for operators. Even for smaller bearings, the power consumption of the ovens is great, worst if it is used intermittently and needs to stay on for the next use in order to avoid having to start from scratch. The burn hazard is also greater as the user will have to reach into the oven to remove a bearing and not knowing if the bearing is actually at the oven’s temperature at any given time is also not reassuring. In comparison, with an Induction Heater you always know the temperature of the I.D. of the bearing, the efficiency and power consumption is much better since the Induction Heater is only on when heating and the burn hazard is reduced as the only thing that is hot is the bearing, so as long as the user uses his/her PPE they will be safe.
*Note: The best Induction Heaters actually offer two temperature probes so that you can mount the probes on both the inner and outer diameters of the bearing, and automatically modulates the heating cycles to monitor the differences between these (a best practice) so as not to stress your bearing, a particularly valuable feature for expensive or high precision bearings. Always try to use one of these types of Induction Heaters is possible.
**Note: Never use an Induction Heater that does not automatically demagnetize your bearing after the heating cycle is completed.
For more information, download our Induction Heating Procedure Bearing Mounting a simple and safe way to properly install your bearings. Mount your bearings quick, clean, and easy thus increase the life of your bearings!
Induction Heating by Bernd Seidenthal CRL