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When looking for an induction heater, below are some recommendations to help with your buying decision:

  1. Size: Choose bearing heater based on maximum workpiece weight, or minimum inner (ID) and maximum outer (OD) diameter.
  2. Temperature control, single or dual: One temperature probe minimum, but two is ideal. To monitor the temperature of the bearing or workpiece a temperature sensor is required. For precision bearings, use an induction heater like the SURETHERM which features two temperature probes to accurately monitor the difference in temperature between the ID and the OD in order not to exceed the bearing’s maximum temperature differential requirements, thereby ensuring 100% tension-free heating.
  3. Automatic Demagnetizing: The process of induction heating magnetizes the bearing or workpiece, therefore an automatic demagnetizing cycle is essential in order to leave no residual magnetism that would cause debris to adhere and accumulate on the bearing.
  4. Multiple crossbars: Different workpieces have different ID sizes, so having the proper size yoke or crossbar is necessary for efficient heating of the workpiece. Always choose the largest crossbar that will fit through the bore of your workpiece.
  5. Automatic temperature hold-mode: Holding the desired temperature when reached is essential since you are not always ready to install the bearing when the heating cycle has concluded. Let the bearing wait on the person, and not the person on the bearing.
  6. Timed heating mode: If heating identical bearings one after the other in a production environment, timed mode will be faster and more efficient than temperature mode.
  7. Delayed start time (safety): Allows the user enough time to step back from the heater before it starts heating, in case the user has a pacemaker.
  8. Fail-Safe error warning: If the probe was not placed on the bearing, or falls off during the heating cycle, the heater will automatically stop in order not to overheat the bearing (if the heater is operated in either of the temperature modes).
  9. Reporting, graphing of time/temperature cycle and printing capabilities: For ISO 9000 compliance, a documentation capability to report how bearing was heated and how long it took and to which temperature the bearing it was heated would be ideal.
  10. Display temperature in degrees C or F on demand.

 

 

by Diana Pereda

In order to heat a bearing for proper bearing installation, you can use multiple methods. In this case I will compare using an Oil Bath Heater to using an Induction Heater.

In an Oil Bath Heater you need a container which will be filled with oil and heated in order to place a bearing in the hot oil to heat the bearing.

Using proper protection is essential in using Oil Baths; you also need to be absolute certain that the container and the oil within is clean. If the oil was previously used then that oil must be filtered to remove contaminants.

Monitoring of the temperature is imperative, not only to make sure that you do not overheat the bearing but also that you do not reach the oil’s flash point and create a fire hazard. You also need to make sure that there is enough oil in the container to cover the volume of the bearing. This will allow the bearing to reach the temperature of the oil and sufficient time needs to be alotted for this to take place.

Once the bearing has reached the desired temperature, absolute care needs to be taken with the excess oil that will be on the bearing—wearing your Personal Protective Equipment (PPE) is essential. If a pre-lubricated bearing was heated it is important to completely clean the bearing and new bearing lubrication be added.

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 or crossbar for the I.D. of the bearing being heated. Also make sure gloves are used to handle the bearing after the heating cycle is complete.

Place the bearing with either the horizontal yoke going through the bore or one of the vertical posts going through the bore. Set the desired temperature on the induction heater, make sure to place the temperature probe on the inner bore or ring of the bearing not on the outer diameter part.* Select 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.

Comparison: The induction heater has the major advantage over the oil bath method. Several things stand out immediately, safety foremost among them, along with precise temperature monitoring and control. Safety-wise, the oil bath method has some serious drawbacks, chief among them the burn hazards to the operator, respiratory hazards and the possibility of flash fires. In addition, the possibility of contaminating the bearing and poor temperature control are other significant disadvantages compared to induction heating. The temperature is being set for the oil, it is difficult to gauge the temperature of the bearing as it is submerged in the oil.

*Note: Best induction heaters like our SURETHERM 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 particularly valuable feature for expensive or high precision bearings. Always try to use one of these types of induction heaters if possible.

** Never use an induction heater that does not automatically fully demagnetize your bearing after the heating cycle has completed.

by Ana Maria Delgado, CRL

Bearings are probably the more complex designed component of any rotating equipment; yet, they are the most misunderstood by the maintenance practitioners who handle them on a daily basis.” —Holcombe Baird, Reliability Center, Inc.

If experiencing premature bearing failures, you should not only look at bearing lubrication practices but also at bearing installation practices. When using an induction heater it is important to make sure that the heating is steady and even; fast is not always good, especially if you do not know what is happening with the temperature of the OD of your bearing. Remember that the inner race heats faster than the outer race. Precision bearings are prime candidates.

In the picture above, on the left you see a single temperature probe, placed on the ID of the bearing, and by the time the temperature of the ID reaches 110° C, the temperature of the OD is only 60° C. This could be a huge problem if the clearance between the ball or roller bearings and the raceways of the ID and OD is not enough to handle the temperature difference. In these cases the bearing balls or rollers get squeezed between the OD and ID damaging the bearing before it is even installed.

Read my entire article at Reliable Plant

Many thanks to Rick Trichka with TM Induction Heating and to Robert “Bob” Latino and Holcome Baird at Reliability Center, Inc. for their input.

by Ana Maria Delgado, CRL

  1. Make sure the surfaces of the vertical posts are clean.
  2. Improve the contact between the vertical post and the crossbar by applying a light coat of Vaseline or grease to the contact surface of the vertical post.
  3. The temperature probe should always be placed on or as close as possible to the inner race or ID of the workpiece being heated.
  4. When possible make sure a second probe is placed on the outer race or OD of the workpiece being heated to also track the temperature of the OD, in line with the ID probe.
  5. For the most efficient heating, always use the largest possible crossbar that will fit through the ID of the workpiece being heated. Stacking of multiple crossbars is permissible.
  6. It is not a requirement that the workpiece must touch the crossbar(s). Just so long as the bar goes through the bore (ID) someplace.
  7. Most important of all is that the workpiece being heated always be automatically demagnetized. Any induction heater that does not do this automatically COSTS you money instead of saving it.

by Bernd Seidenthal CRL


LUDECA is proud to announce that effective October 20,  2017, LUDECA is certified as an authorized TM Induction Heating Service and Repair Center for the United States.
Our factory trained technicians are highly experienced, and committed to providing our customers with excellent service.
We look forward to servicing your TM Induction Heating products at our Doral, Florida location.
For more information, visit our website.

by Ana Maria Delgado, CRL

It seems that every maintenance department has a hard time installing bearings because of the problems inherent in conventional heating methods.

Applying care, good technique and heating methods is better. Over 90% of rotating equipment has defects at startup that can result in equipment failure.

One reason bearing installation is often a herculean task is not using proper heating methods. Excessive heat applied to the bearing during installation can introduce defects that lead to premature equipment failure.  Instead, heating a bearing up on an induction heater, automatically demagnetizing it, and then slipping it on the shaft free of stresses is the way it should be done. The results of overheating a bearing are increased maintenance cost, increased safety risks, and more equipment downtime.

Proper heating methods and best practices should be applied to correctly install bearings.  Induction heaters such as SURETHERM can help eliminate induced bearing defects due to poor fitting and improper mounting techniques.  Induction bearing heaters provide increased safety, increased efficiency and reduce the risk of bearing contamination and damage that can result from using brute strength, oil baths, blow torches or other improper methods of heating bearings for proper installation.

Here are some conventional methods that are used in Industry and why they are not the way to install bearings:

Blow Torch
 – No temperature control
– Risk of over heating
– Grease leaks out of bearing
– Tension in material

Hot Plate
– No temperature control
– Risk of over heating
– Grease leaks out of bearing
– Tension in material
– Dangerous (plate stays hot)
Oil Bath
– Slow heating process
– New grease cooks out of bearing
– Dangerous (hot oil)
– Environmentally unfriendly
Oven
– Slow heating process
– High energy consumption
– Grease leaks out of bearing

by Bernd Seidenthal CRL

It seems that every maintenance department has at least one Hercules that uses more muscle than technique to complete maintenance activities.  Brute force and strength are occasionally required to complete a task.  Having Hercules around is important when those moments arise.

However,  applying care and good technique are usually better. Over 90% of rotating equipment has defects at startup that result in equipment failure.  One of the reasons arises from making bearing installation a herculean task and not using proper technique.  Excessive force applied during bearing installation can introduce defects that lead to premature equipment failure.  Instead of beating the bearing on with a sledge hammer, gently heat it up on an induction heater, automatically demagnetize it, and then slip it on. If Hercules did the job, then the bearing and equipment are doomed to failure from the moment of startup.  This results in increased maintenance cost, increased risks, increased equipment downtime.

Installing equipment bearings should not be a herculean task.  Instead, proper technique and best practice should be applied to correctly install bearings.  Induction bearing heaters like SURETHERM can help eliminate induced bearing defects due to poor fitting and improper mounting techniques.  Induction bearing heaters provide increased safety, increased efficiency and reduce the risk of bearing contamination and damage that can result from using brute strength, oil baths, blow torches or other improper methods to heat bearings for proper installation.

by Trent Phillips