AUGUST 2020 – PUMPS AND SYSTEMS
Improper bearing installation is a common cause of bearing failure. If a bearing is damaged during installation, no amount of lubrication or alignment will save that bearing. At best, it will only prolong its inevitable premature failure.
Poor bearing installation starts with poor bearing storage. It is important to ensure that bearings are kept in an area with constant temperature and humidity, making sure the oldest bearings are used first, keeping the bearings in their protective packaging, and laying them flat as opposed to hanging them. Make sure the environment is vibration-free and clean, in order to prevent particle ingress contamination. One big problem with poor bearing installation is the method that is used to install the bearings. This also holds true for gears, hubs, rings, and any other workpiece that needs to be heated to be mounted on a shaft.
Download our Bearing Storage Best Practices for some basics things to prevent bearing damage and contamination thus maximize bearing life and performance.
Other problems are selecting the correct bearing, measuring to confirm that the interference fit is correct, making sure to clean the shaft on which the bearing will be placed, and not contaminating the bearing during handling.
Another problem is overheating. It is imperative to maintain an even temperature throughout the bearing while installing it and make sure never to exceed 250 F (121 C.)
Once the correct bearing has been selected, it has been measured to confirm the selection, and the shaft is free of contaminants and burrs, now comes the selection of the method used to mount the bearing. The selection can either give the bearing a long, healthy life or condemn it to death before it rotates even once.
There are several methods that can be used to heat a bearing for installation:
- Blow torch
- Brute force (sledgehammer)
- Oil bath
- Hot plate
- Cone heater
- Induction heater
Click here to read the entire article, “Avoid Poor Bearing Storage & Installation” to find out more about the methods along with the pros and cons used to heat a bearing for installation.
Download our Induction Heating Procedure – Bearing Mounting for a simple and safe procedure for proper bearing installation.
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 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!
by Diana Pereda
For many years, applying heat was explained as simply just that, applying heat. How it was done was usually left totally up to interpretation. In a field application, this could be left to the discretion of the crew doing the job, based on either what was available or considered most effective/least expensive/easiest. Any one of these criteria could doom a piece of equipment to an early demise. The same holds true for a shop application, where it is assumed that resources and tools are much more readily available. In either setting, a little information about how the equipment and parts are designed to work can shed a ton of light as to how heat should be properly applied.
For an installation of, say, a coupling hub to a shaft, there is always a specification given for what the hub bore should be to fit a certain sized shaft and these dimensions should be checked first. Over-heating a hub to make it go over a shaft that is just a hair over specified will not work. This will end up possibly damaging the hub through distortion and even weakening the structure (not what you want in a hub that could be transmitting thousands of horsepower.)
Most coupling manufacturers have a specification that pertains directly to the product they are selling for specific applications, but here are some guidelines.
Straight Bore – Interference fit with keyways:
Shaft Diameter (in.) Interference Fit (in.)
.5″ to 2″ 0.0005″ to 0.0015″
2″ to 6″ 0.0005″ to 0.0020″
6″ and up 0.0001″ to 0.00035″
Splined Shaft – Slight Interference fit
0.0005″ To prevent backlash or fretting of the hub
Tapered Bore – for high speeds and high torque
Interference fit of 0.001″ per 1″ of shaft diameter
With tolerances like this, betting that a little extra heat will get a job out of a bind just does not make sense. Knowing these tolerance values up front lets the technician know that a few measurements will go far towards making sure the work goes as planned. Accurate measurements of the ID for the hub and OD for the shaft will show if the diameters are right for the installation. Once that is established, the phase of applying the heat can begin! So how is it to be done…..?
Does anyone have a clue as to how hot this is getting? It is an impressive collection of rosebud torches, and it appears that they are all heating the material, but clearly hotspots can be seen. Even the manufacturer has notes about this.
“The hub may have to be heated in order to reach the desired position on the shaft. DO NOT SPOT HEAT THE HUB OR DISTORTION MAY OCCUR. Install shaft locknut to hold hub in place”
Maybe the results of work performed like this has been observed in the past. Did the equipment run efficiently? Did it exhibit vibration? Did it even make it to the first service interval?
Knowing that this hub had “heat applied” to the point that it is permanently discolored the metal could help explain runout issues when trying to align this hub to the driving shaft. And even if the alignment can be done within tolerance, what forces will the bearings see? And what is happening to clearance for the shaft? Oil analysis might even start giving clues right away that there is a problem.
Proper application of heat with an induction heater eliminates all of the issues talked about so far. The induction heater guarantees that heat is evenly and accurately applied to the workpiece, and that the workpiece is fully demagnetized before installation. If the technician has measured the bore and the shaft, cleaned everything properly for installation, and used an induction heater to achieve the proper temperature, this job should go off without a hitch. Furthermore, there should be a report that showed how the hub was heated, over what span of time, and to what specified temperature. This eliminates a large amount of investigation (and possibly blame) in the event that a Failure Analysis investigation needs to be conducted.
Download our Basics of Induction Heating white paper and learn the basic principle behind induction heating, the diverse range of applications and advantages, and the different types of equipment you can use to reach your goals.
by Diana Pereda
Once again, I was struck by a smart sign that reminded me of the importance of safety: “TAKE FIVE for SAFETY.” This one popped up while touring the APM Training and Development Center in Houston, Texas after our #NoExcuses for Equipment and Bearing Failures workshop.
It was the perfect closing theme to a day of learning how planned and precision maintenance practices, along with step-by-step procedures, not only reduce equipment failures but, most importantly, move us away from rushed reactive work that increases the risk of personal injury.
We had started our learning day taking five minutes to review safety procedures in the building. Later during the tour of the amazing APM training facilities, we had taken five to put on our personal protective equipment (PPE) to get near their mega GE turbines. Their commitment to safety at all times prompted me to share with you my five takeaways from our workshop for reliable work that will also deliver safety:
- Prepare and plan your work. This quote from President Lincoln reminds us of the importance of preparation to get the job done right:
Give me six hours to chop down a tree and I will spend the first four sharpening the axe.” ― Abraham Lincoln
- Torches, rosebuds, and oil baths are not safe methods to heat your bearings, as they will almost surely result in burns and damage your bearings. Instead, consider heating your bearings and other workpieces using safe induction heating. It’s a clean, faster, and more accurate method, whether in the shop or in the field and best of all, safe!
- Electrical faults are dangerous! Taking five to reduce personal injury by adding ultrasound to inspect your electrical systems for arcing, tracking and corona is the best work safety practice.
- Also, use ultrasound to detect dangerous leaks such as gas and ammonia before you step in there and breathe it in.
- Protect your assets, both people and equipment, by implementing the following five steps along with precision maintenance technologies:
- Stop and think about the potential dangers associated with the job.
- Look for and identify any hazards.
- Assess the risk; consider any possible risk of damage or injury.
- Control hazards by implementing suitable control measures to reduce the risk.
- Monitor hazards to successfully mitigate the likelihood of injuries or damages as you work.
Further, I found this information about “Take 5 for Safety” that you may find useful for your facility:
The above-listed Take 5 Safety checklist is a tool used to identify health and safety hazards before starting work at a site. Performing health and safety checks using the take 5 procedure (Stop, Look, Assess, Control, and Monitor) helps workers and contractors mitigate exposure to injury hazards and health risks.
Click here if you missed and want to read my previous safety post: Heaven can wait! Safety first. Always lock-out and tag-out your machines.
by Ana Maria Delgado, CRL
Predictive maintenance plays a huge part in the overall reliability of your assets. Most of the time, equipment fails because of a bearing or seal failure. Bearing failures are very common, and improper installation of a bearing is one of the biggest reasons it fails. If you don’t do it right, and with the proper tools, you are going to damage the bearing and it is only a matter of when rather than how. Before installing a bearing, you need to have a clean space and all the necessary tools should be with you when you are installing it. You also have to make sure that the storage of the bearing is correct. There are a number of ways that you can go wrong with improper storage and handling of bearings.
Overheating is a huge issue that is often observed while installing a bearing. There are multiple ways to heat a bearing before installation. You can use an oven, or a hot oil bath where you dip the bearing in boiling oil and heat it until you hope you get the right bearing temperature. You can also use a hot plate where you need to keep flipping the bearing over and over to try to get an even temperature on both sides. Another, and by far the best method is to use an induction heater. These come in different sizes, to handle from the smallest to the largest bearings with ease. They use eddy current heating and the system monitors the precise temperature of the bearing for you until it reaches the desired temperature. You need to take proper safety measures in every case.
Induction heaters are also the most efficient in terms of power consumption and the time it takes to achieve the precise temperature that you need. Temperature is the key here and for bearings it should always fall between 220 and 230 degrees F, but never above 250 degrees. Induction heaters are also good for sealed bearings in that they don’t damage the seals or contaminate the new lubricant in the bearing while heating it. Then you have to make sure that the shaft is clean and not damaged. Sometimes, the shaft is compromised when a bearing is removed because brute force was used to remove it. You need to have the proper tools so that you will be able to remove the bearing without damaging the shaft or any other vital component of the machine. You should also make sure that you are installing the right bearing with right tolerances, at the right place and at the right temperature.
The person installing the bearing needs to have just basic training to install it properly, when using a good induction heater. They should know how to operate the induction heater, have knowledge of safety procedures, and proper installation techniques. You should trend this in your facility so that a culture shift toward continuous improvement in your procedures is maintained. The mindset of the personnel is very important here because they are the ones who will have to make these practices consistent with time. Proper bearing installation prevents a lot of failures and saves you lots of time and money in the end. Download our Induction Heating Procedure – A simple and safe procedure for proper bearing installation.
Hear more from Bernd Seidenthal in this podcast by James Kovacevic and learn more about how to avoid bearing failures and the necessary tools you need, the steps, and value of proper bearing installation.
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 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.
by Diana Pereda
When looking for an induction heater, below are some recommendations to help with your buying decision:
- Size: Choose bearing heater based on maximum workpiece weight, or minimum inner (ID) and maximum outer (OD) diameter.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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.
- 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).
- 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.
- 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
- Make sure the surfaces of the vertical posts are clean.
- 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.
- The temperature probe should always be placed on or as close as possible to the inner race or ID of the workpiece being heated.
- 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.
- 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.
- 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.
- 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 are 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 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, blowtorches 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:
Heating a Bearing with a Blowtorch
Heating a Bearing using a Hot Plate
Heating a Bearing in an Oil Bath
Heating a Bearing in an Oven
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