Static, Couple, and Dynamic Unbalance

According to the International Organization for Standardization (ISO), unbalance is “that condition which exists in a rotor when the vibratory force or motion is imparted to bearings as a result of centrifugal forces”. In other words, unbalance is an unequal weight distribution of a rotor around its rotating centerline. The rotating centerline or rotational axis…

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Balancing How To #6 – Balancing Tolerances

By now, if you’ve kept up with the VibrAlign balancing “how-to” blogs, you should see that balancing is mostly just a math problem – counteracting forces.  But we haven’t discussed when the balance job is through. When I started balancing fans many years ago, I stopped balancing when: The fan owner said, “that’s much better”,…

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Vibration Analysis: Where to Start

  Vibration analysis is a useful way to monitor machine health. Many plants have implemented regular vibration analysis plans to ensure the condition of their machines is being checked at regular intervals and so, if an issue comes to light after spectral analysis, a solution can be pursued. When analyzing vibration, it is important to…

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How to Differentiate Unbalance and Looseness on the Spectrum

  What is the difference between looseness and unbalance? They have very similar spectrums with different influencers. One can even impact the other in some situations. That similarity can impact your ability to balance a machine expeditiously in the field. For clarity of this discussion we will limit it to Type A and B mechanical…

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Finding Unbalance and Misalignment on a Spectrum

  Unbalance and misalignment are problems that need to be addressed as soon as possible, but before you can begin to fix them, first you need to know how to find them on a spectrum. We will go over this below. For example, with a fan, unbalance appears on the spectrum as a higher than…

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Balancing How To #3-Where and How to Place and Affix a Trial Weight

Once unbalance is determined, the original unbalance run (amplitude and phase) is measured, and a trial weight size is determined, the next step is where to place the trial weight. If you have no balancing record for this rotor, where to place the weight is little more than a guess.  But there are some things…

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Balancing How To #2 – Selecting a Proper Trial Weight

In our last Balancing How To, we discussed how to set up and get your original measurements on the rotor to be balanced.  This How To discusses selecting a proper trial weight. A trial weight is used to make a change in the original vibration amount and direction.  Changing either the AMOUNT of vibration (amplitude),…

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A Vector Approach to Single Plane Balancing

Unbalance (Imbalance) is often defined as the unequal distribution of the weight of a rotor about its rotating centerline. A rotor can be balanced either in-place or in a balancing machine assuming unbalance is the issue and weight can be added or removed.  Modern balancing instruments will do the math for you. I originally learned…

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Balancing How To #1 – Setting Up for Balancing

The recent blog on troubleshooting balancing ( https://acoem.us/other-topics/smc-touch-tip-using-the-smc-when-unbalance-is-diagnosed/ ) brought up some additional questions from our readers, so let’s tackle them in order. The first one is setting up to perform a balance job. NECESSARY EQUIPMENT FOR BALANCING If you have gone through the checklist and confirmed unbalance, you will need: A machine to perform…

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SMC Touch Tip-Using the SMC When Unbalance is Diagnosed

The Fixturlaser Smart Machine Checker (SMC) is a great balancing tool (for me personally, it’s the best balancer I’ve ever used).  Unbalance is one of the most common machinery problems on rotating equipment, especially fans. If you get a diagnosis of unbalance, be aware of these tips: Be mindful that a rotating mass, once balanced,…

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Too Much Grease (a “liquid” unbalance!)

We recently published a blog about using the Fixturlaser SMC as a lubrication tool. https://acoem.us/other-topics/using-the-smart-machine-checker-as-a-lubrication-tool/ Ironically, just a couple of weeks later I received some photos from a new SMC customer.  He got a report from his SMC stating that a chilled water pump was experiencing motor unbalance.  He took the motor apart to inspect…

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What is the Difference between Unbalance and Runout?

Unbalance and runout are two terms that we hear frequently in the predictive maintenance community. Both unbalance and runout can be serious issues and need to be addressed to prevent inefficient functioning and damage to machines. Unbalance occurs due to corrosion, erosion of the fan wheel, or if a correction weight is removed. Runout occurs…

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The 3 Types of Unbalance You Should Know About

We often hear about how to correct unbalance in rotating machinery, but to correct unbalance, it is first necessary to accurately diagnose what type of unbalance your machine is experiencing so that you can take the proper action to correct the problem. In this post, we will go over the three types of unbalance you…

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TROUBLESHOOTING MOTOR UNBALANCE

Electric motors are almost always well-balanced when they leave the motor manufacturer.  But occasionally, motor unbalance problems are picked up with vibration monitoring tools, such as the OneProd Hawk. Here are some easy troubleshooting methods to determine the cause of unbalance in the motor. An electric motor’s rotor, like any rotating mass, cannot become out…

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