Axial Fan

Material Build-Up On the Wheel
If you have a material handling application or misfit another application with a fan that tends to build up material, fan vibration problems are quite common. When that happens, it’s probably time to clean the wheel. That means shutting down, waiting for all the parts to stop moving, locking out, opening the housing to clean it thoroughly, re-securing it, and starting back up. We recommend putting this on a regular maintenance schedule to avoid vibration issues in the future. The other alternative is to replace the fan wheel with a self-cleaning blade or material of construction.

Deteriorated Fan Wheel
There are many reasons for the deterioration of a fan wheel. Industrial fans can last for decades, so it could just be normal wear over time. Many industrial processes involve corrosive gasses that can wear out the wheel much more quickly, causing the properties of the wheel to change. The vibration comes from the changing properties inside the fan housing on the wheel. In this case, you will likely need to replace the wheel with a new one, potentially designing with corrosive-resistant construction materials.

Loose Fasteners
Loose fasteners are actually quite common and fairly easy to fix. This is especially noticeable if your vibration is on the vertical side of your bearing due to the fasteners at the base of the fan not being secure enough to the floor. If you find that this is the cause of the fan vibration issues, just get out a drill and fasten them down.

Drive Component Misalignment

Regular maintenance requires occasional opening or disassembly and reassembly for things like cleaning, greasing, and part changeouts. That can create the potential for misalignment, which in turn can create fan vibration issues. To fix that, take your straight edge to it. You’ll want to be sure to align the bearings, shaft, coupling, and motor to fully realign the drive.

Defective Bearings
If you’ve got bad or broken down grease or have let the bearings go too long without proper grease maintenance, you will eventually start to get metal on metal and experience vibration. At this point, you’re well on your way to bearing failure. Whether one or both bearings are defective and failing, you must replace them both. You’re far better off ensuring a regular grease maintenance schedule, but bearing failure is one of the most common issues revealed by fan vibration.

Operating Near System Critical Speed or Stalling in the Unstable Region of the Curve
This is another problem that could be very simple or very complex to solve. There is an unstable region on a fan curve just to the left of the peak, where you’ll experience fan vibration, surges, or stalling. That could be due to something as simple as a damper that needs to be closed or opened, or it could be something much more complex in the workings of the fan. If you can control the airflow to avoid the unstable region and stay under system-critical speed, you should easily avoid or address this type of fan vibration.

Operating In – or Near – a Resonant Frequency
A resonant frequency is a specific frequency that “excites” your fan. It’s not exactly a performance problem; it’s just not a good frequency for the particular wheel design of the fan, so it causes vibrations. If you’re having vibrations due to a resonant frequency, you should be sure to avoid it, and that should resolve the fan vibration problems.