Just what does it take to be successful at balancing? Let’s start with some basics. First you need to have an understanding of the balancing process, next nomenclature: is it unbalance, imbalance, out of balance, or what? Use a consistent description and stick with it. Next, think about what the source of unbalance could be: is it uneven wear on parts? Voids within castings? Damage from impacting? Material buildup? Even though buildup is not usually a problem, when it begins to come off it rarely does so evenly thus creating an unbalance. In other words, unbalance is simply the uneven distribution of mass.
Simply review or collect data to ensure that the undesirable vibration is from unbalance and not some other issue such as a belt problem, misalignment, electrical issue, etc. Once you’ve determined that the vibration is indeed unbalance you need to inspect the object to be balanced. If it is not clean, clean it. Look for damaged or broken parts. On belt driven equipment inspect the belts as their frequency can be very close to running speed and can hinder the balance job. Make sure you have the proper tools for doing the balancing job, such as a balancing instrument capable of reading the vibration that is produced at running speed or what is commonly referred to as 1×or 1 times and capable of indicating the phase angle at 1×. This could involve utilizing an optical tachometer, laser tachometer, magnetic pickup or even a stroboscope. Some tachometers will require a piece of reflective tape on the shaft for the tachometer to read from and this might require stopping the machine if still in service.
Tip: I try to place the tape horizontally, or along the axis of the shaft, with the leading edge of the tape on the trailing edge of the key way. This can be helpful if you ever have to return for another balancing job on the same machine. You need to determine if you will be adding or removing material in order to balance the rotating component. If removing material, how will you determine how much you’ve removed;if adding weight, you need to make sure the weight you are adding is of a material that is compatible with the service the machine is exposed to. If adding material “weights”, how will they be attached? With set screws? Bolts? Clamps? Welded on? All this should be considered. One last tip: if after two runs you’re not there or almost there yet, you might need to stop and examine your process to ensure no mistakes have been made.
Download LUDECA’s 5-Step Balancing Procedure.
by Gary James CRL
As Published by Maintenance Technology Magazine September 2017 issue
If greater reliability and uptime are of any concern to you, then precision maintenance is a key component in achieving it. This means having clear and simple, yet meaningful, procedures in place for the different tasks involved. Two such tasks are precision alignment and balancing. LUDECA’s 5-Step Procedures will help guide your facility and maintenance staff to achieving precision maintenance.
The alignment and balancing procedures lay out the basic steps required to align and balance machines safely, reducing risk of injury and increasing likelihood of a quality outcome. Checklists simplify the workflow and serve to remind employees of the processes required to consistently and safely perform the precision maintenance task.
Well-aligned and balanced machines run more reliably, with a greatly reduced probability of failure. This allows for better maintenance planning, greatly reduced repair and maintenance expenses, increased uptime and more profits.
A good alignment procedure ensure that machines are aligned to the proper tolerances for the running condition of the machines, taking into account such things as thermal growth and anticipated positional changes. This ensures that the greatest efficiency is achieved in your running machinery, prolonging their health and reducing power consumption. Studies have shown that well-aligned machines result in a 3% to 10% reduction in power consumption. Noise and heat generation is reduced, producing a safer work environment.
- Production Quality
Good alignment and balancing result in better product quality since vibration is minimized, resulting in a more uniform and higher product quality. Unexpected breakdowns in production machinery may lead to costly waste from scrappage and high restart costs for the production line.
- Training & Procedural Consistency
Once implemented, a procedure ensures all employees involved in the activity face clear and consistent expectations and processes, leading to a better understanding between all staff in the facility. Training expense can be reduced since often only refresher training is required to update understanding of the technology utilized as updates are rolled out. Records should be kept that document employee training.
The next step in precision maintenance and reliability is the Implementation of formal specifications that detail every step in a task from safety to activity process to documentation, to ensure that anyone involved can follow the procedures and guidelines without confusion, and reach the desired outcome for all machinery types in the plant. Such specifications typically take from two to three months to develop and a further two to three months to roll out and fully implement. LUDECA has written a number of these specifications for customers worldwide. Let us help you as well.
by Alan Luedeking CRL CMRP
Guest Post by Bob Dunn from I&E Central, Inc.
A customer was having difficulty balancing the rotor shown above. They had made multiple corrections, some contradictory, and were worse than when they started. In that this is on a shop stand and controlled conditions, something was not right. Looking at the photo, I saw a couple of likely issues.
- The shaft is pretty reflective itself, it is doubtful that they were getting a good or consistent phase reading. I recommended they put a ring of black tape on the shaft, with the reflective tape on the black.
- The tach sensor is pointing at the shaft at about a 90 degree angle. Optical sensors and reflective tape works better if the sensor is aimed at an angle – 30 degrees or so.
- The tach sensor is pretty close to the rotor. In this case it is not too close, but you can be too close. A sensor like this will work from several feet away, if you are having problems, try moving the speed sensor further away.
The customer applied the tape and adjusted the tach position. The rotor was balanced in a single run.
by Yolanda Lopez
Proper equipment function requires a properly aligned and balanced machine. Allowing a machine to operate with an unbalance condition can result in bearing damage, cracks, loose components and many other costly maintenance issues. Loose debris can dislodge and impact the balance quality of a machine. Debris buildup on the impellers/blades, and other rotating parts can create unbalance conditions. Before balancing the machine it is very important that the rotating surfaces (blades, etc.) are cleaned of any debris. Removing buildup will help ensure that the machine can be properly balanced and remains in a balanced condition.
by Trent Phillips CRL CMRP - Novelis
The practice of reliability has many tools, processes and methodologies that can and should be implemented within a facility. Try as we may, it is usually not possible to implement and sustain all of them. So the challenge quickly becomes deciding which aspects of reliability to implement and in what order!
Implementation and enforcement of standardized work procedures is a very critical aspect of reliability and should be at the very top of your list of required reliability tools! Standard procedures focusing on fundamentals such as proper torquing, alignment, balancing, bearing installation, and equipment installation, should be in place. In addition, standard procedures for work request, work approval, planning, scheduling and work execution should be implemented as well.
Make sure that standard procedures are in place to execute the reliability methodologies at your facility. Otherwise, your site may always find it difficult to achieve sustainable and best practice maintenance and reliability.
Why? Unfortunately, people are usually the biggest obstacle we face in our jobs. People do not like to change, forget or misunderstand what needs to be done. Standard procedures will help ensure that reliability processes are routinely followed and things do not fall backwards to the unreliable way they have always been done. Additionally, it will provide the ability to track how well your facility or company is doing at implementing, executing and maintaining the reliability practices desired.
by Trent Phillips CRL CMRP - Novelis
- Right safety procedures before you balance.
- Right machines to balance.
- Right balancing procedure.
- Right balancing tool.
- Right balancing tolerances ISO or API.
- Right data collection
- Right weights.
- Right weights locations.
- Right corrections.
- Right balancing report.
Download [Infographic] 5-Step Balancing Procedure
by Ana Maria Delgado, CRL
Precision balancing is an essential part of a proactive reliability program as it can eliminate many machine failures and defects. This Infographic outlines an easy and effective way to balance your rotating equipment.
by Ana Maria Delgado, CRL
In today’s world, video platform is the way to accomplish effective visual knowledge and a learning mechanism in many organizations. With the use of video, one not only is able to promote products and services but one can also strengthen a culture and demonstrate how-to scenarios easily and quickly.
LUDECA believes in communicating visually to help customers educate and train their personnel on precision skills. For this reason, we are pleased to announce the release of our new microsite www.LudecaVideos.com, which features a Shaft Alignment Know-How series plus a Know-How series for Vibration Analysis and Balancing. The video site features basic terminology, fundamental concepts, advanced measurements as well as product demonstrations. The videos are indexed by category but also searchable by keyword.
We felt there was a need to go back to basics and help educate on precision skills and related technology to improve asset reliability. Following the Uptime Elements™ holistic approach to reliability, alignment and balancing are key components of your asset condition management (ACM) program. We are happy to offer these videos to our customers for their personnel to access and for use in their training programs. We hope this content assists them and others in either improving their reliability program or in getting one started and leads to world-class reliability programs,” —Frank Seidenthal, president of LUDECA.
We encourage you to visit www.LudecaVideos.com and see for yourself the value behind each video.
by Yolanda Lopez
The following blog relates to those who field balance using a photo or laser tach and reflective tape.
By far the most common pitfall to field balancing is a problematic tach signal. When one balances a rotor using one’s field balancing unit (VIBXPERT II, VIBXPERT or VIBSCANNER) the equipment is recording the energy displayed at the frequency of the signal from the tachometer. To help visualize the importance of a clear tachometer signal that is exactly 1 pulse per revolution, look at figure 1.
What amplitude will your equipment record if the tach pulses:
1. 1,195 times per minute?
2. 2,002 times per minute?
3. 2,006 times per minute?
4. 2,011 times per minute?
5. 2,013 times per minute?
We often start a balance job by haphazardly placing our tach and tape. Because both the tach and tape are well engineered, we may go on without a problem. But just a little attention to some of the common tach signal problems is usually all it takes to avoid having to restart a botched attempt at field balancing. What should be avoided when setting up a tachometer?
1. Don’t place your tach too close to the rotor. Most tachometers used in the field work by sending some type of light out and bouncing it back, so they have a sending function and a receiving function. The wavelength of the light is such that not just any light will be accepted by the receiver, but only that wavelength of light sent out by the sending unit. So the receiver counts a pulse every time that wavelength of light appears (or disappears, depending on whether you are triggering by leading or trailing edge). The receiver is no smarter than that, we must supply the rest of the intelligence. When we put the receiver too close to the rotor, even a poor reflector may be able to bounce back enough of the light signal to create a pulse. The balancing technician should determine the distance from the rotor to set up their tach with the understanding that they want a good signal bounced back from their chosen reflector, AND ONLY THEIR CHOSEN REFLECTOR! Most often, a 6 inch space is sufficient.
2. Don’t place your tach pointing perpendicular to the rotor. Earlier we stated that “both the tach and tape are well engineered”. One thing most of us field balancers take for granted is the reflective tape. This tape is actually a well-engineered tool. Reflective tape is faceted in such a way that light can strike it at an acute angle, and still be reflected right back along the axis from which it came. This allows the tach to be staged at such an angle that light will strike the rotor, even a rotor that is itself a good reflector, and be reflected off and away from the receiver UNTIL the tape comes into the line of the light, and then with its special faceting, it will bounce the light back to the receiver. This gives one clean pulse every time the tape comes around, and only when the tape comes around.
3. Don’t use old reflective tape that may not be in proper working condition. Make sure the tape is clean and in good shape. Reflective tape works very well when it is clean and in like-new condition, but can get dirty or even deteriorate if conditions are right. Replacing a small piece of tape is most often very quick, easy, and cheap compared to extra balancing runs or possibly even worse.
4. Don’t use a tach with dirty lenses. Make sure the tach lenses are clean and in good shape. When your lens is dirty, it forces you to do things (in order to get a strong enough signal to go through the dirty lens) that aren’t conducive to a clean, clear, once per revolution pulse; like move the tach too close to the rotor, or place it at a 90° angle to the rotor.
Doing everything we have suggested here could take all of 5 minutes (if you work slowly) at the beginning of a field balance job, but it could save a lot!
by Mike Fitch CRL
Recently I visited a customer’s facility to provide onsite training for the VibXpert vibration data analyzer they had recently purchased. Before we could get started collecting data, we needed to build the equipment hierarchy and measurement templates required. Once the database was created, we loaded routes into the VibXpert and proceeded to collect vibration data.
The first room we entered had two large belt driven overhung fans. At first glance it was obvious that one of the fans was running extremely rough. We collected vibration data on both fans and paused to review the results. We noticed that the 1× amplitude on the rough fan was over 1.0 inches per second peek. The local CM technician immediately commented that the fan should be balanced and his observation was correct when simply looking at the vibration data.
The room was full of clues which explained the cause of the fan unbalance. This facility processed and manufactured wood products. Large amounts of wood dust are produced and these fans were designed to ventilate a high dust area. Everything in the room was covered with wood particles and dust. The only question was how much had accumulated on the inside of these fans.
I asked if the fan could be stopped for a short period and the inspection door opened. My request was honored and the fan was shut down and locked out. Our examination revealed the fan blades had amassed substantial amounts of wood particles. The fan blades were cleaned and resulting in a pile of wood chips weighing about 5 lbs. The fan was placed back into operation and allowed to run for several minutes. Vibration data was recollected on the fan and the 1× amplitude had reduced to 0.1 inches per second.
Fans require corrective action to eliminate unbalance conditions from time to time. However, the cause of unbalance may simply be buildup of foreign matter on the blades. This fan was being allowed to beat itself to death due to product buildup. This facility learned a few lessons from the experience. First, inspections utilizing the human senses (touch, hearing, etc) could have been used to determine that this fan was in need of attention. Second, periodic vibration monitoring would have identified a need for maintenance on this fan. Third, if a fan is properly balanced, simply cleaning foreign matter buildup may reduce the vibration, prevent equipment damage and maintain the reliability of the equipment. Make sure that you utilize these three steps during your daily maintenance efforts on equipment.
by Dave Leach CRL CMRT CMRP