In order to heat a bearing for proper bearing installation, you can use multiple methods. In this case I will compare using a hot plate to using an Induction Heater.
Hot plates come in different shapes and sizes but in essence it is a plate that will heat up, and onto which a bearing will be placed in order to heat it.
Using proper protection is essential when using a hot plate as the surface will be very hot. It is important to ensure that the surface of the Hot plate is clean so as to not contaminate the bearing that will be heated.
Make sure to wear your Personal Protective Equipment (PPE) while handling the bearing and being near the surface of the hot plate. Careful monitoring of the temperature is imperative to make sure that you do not overheat the bearing. Set the temperature on the hot plate to the desired setting; once the hot plate reaches the desired temperature place the bearing on the hot plate and make sure you turn the bearing often so that both sides heat evenly. Use an external thermometer or temperature measurement device (thermometer, temperature sticks, infrared heat sensor) to make sure that the bearing reaches the required temperature to be fitted on the shaft. Again, make sure that both sides of the bearing have the same temperature.
Sealed Bearing should not be heated on a hot plate, as the seal will be compromised through direct contact with the hot plate surface.
In contrast with a hotplate, if an Induction Heater is used, make sure that you are using the correct size Induction Heater for the weight of the bearing, and also make sure that you are using the largest possible yoke (crossbar) for the I.D. of the baring being heated. Use appropriate gloves to handle the bearing after the heating cycle is complete.
Place the bearing with either the horizontal yoke (crossbar) going through the bore, or over one of the vertical posts going through the bore. Set the desired temperature (not to exceed 250° F) on the Induction Heater using its control panel, and place the temperature probe on the I.D. (inner bore diameter) of the bearing.* Now press start to begin the heating cycle. Once the heating cycle is completed and the bearing has automatically been demagnetized**, install the bearing on the shaft.
The Induction Heater has the advantage over the hot plate method. Several things stand out immediately, safety foremost among them, along with precise temperature monitoring and control. The hot plate method has some safety drawbacks such as a burn hazard, since ideally the hot plate needs to reach the desired temperature before placing the bearing on it, creating an area hazard. Also, having to constantly handle the bearing to make sure that both sides are heated equally increases the probability of dropping the bearing and poor temperature control of the bearing.
* 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 modulate the heating cycles to monitor the difference between these (a Best Practice) so as not to stress your bearing, a particular valuable features for expensive or high precision bearings. Always try to use one of these types of Induction Heaters is possible.
** Never use an Induction Heater that does not fully and automatically demagnetize your bearing after the heating cycle is completed.
Induction Heating by Bernd Seidenthal CRL