Industrial fan failure modes

Defining and detecting industrial fan failure modes is key to ensuring safe and effective production in many industries. This is your guide to proper failure mode handling.

Contents

Intro to industrial fans 2

Different types of industrial fans 3

Failure mode overview 5

Failure modes 6

Bearing failure 6

Imbalance 6

Blade damage 6

Electric drive motor failure 7

Misalignment and shaft failure 7

Blockages 7

Pressure instabilities 8

Resonances 8

Loose fundament 8

Damper faults 8

General wear and tear 9

Intro to industrial fans

Industrial fans are essential components across many sectors, including manufacturing, HVAC, power generation, and mining. They move air or gas in various processes such as ventilation, cooling, material handling, and exhaust. While all fans serve a similar purpose—air movement—their designs and performance characteristics vary significantly.

When industrial fans malfunction, the impact on a factory can range from minor inefficiencies to serious production stoppages or safety risks, depending on the fan’s role in the process. Below is a breakdown of the typical consequences of industrial fan failure mode malfunctions and how they affect operations: 

1. Reduced or Lost Airflow

• Fan speed drops, airflow is blocked, or stops entirely.
• Can lead to overheating, poor ventilation, or pressure imbalances.

2. Overheating of Equipment or Products

• In cooling applications (like electronics, kilns, or compressors), a failed fan can cause temperature spikes, damaging sensitive equipment or materials.

3. Process Disruption

• Fans used in drying, fume extraction, combustion air supply, or material transport are often essential to production.
• Failure can halt production lines or reduce throughput.

4. Safety Hazards

• Poor ventilation leads to heat buildup, toxic gas accumulation, or dust explosions in extreme cases.
• Malfunctioning fans can compromise air quality and safety standards in confined spaces or cleanrooms.

5. Increased Energy Consumption

• A faulty or imbalanced fan draws more power to compensate.
• Reduced efficiency = higher operational costs.

6. Damage to Connected Systems

• If a fan fails catastrophically (e.g., bearing failure, blade detachment), it can:
  • Damage ductwork
  • Causes unbalanced loads on motors or drives
  • Lead to chain-reaction failures in adjacent systems

Different types of industrial fans

There are many kinds of fans, but the most common types are axial fans, centrifugal (radial) fans, mixed-flow fans, and crossflow (tangential) fans. 

Different fan types have different physical characteristics. Industrial fans are often customized for a particular installation and will have their unique signature for imminent failure. Due to the unique signatures, trend monitoring of vibration, temperature, and currents is very suitable for industrial fan maintenance programs.

Fortunately, all industrial fan types have quite similar failure modes, with bearing fault, imbalance, misalignment, and motor failure being the most common.

We have created this guide to help you develop a strong maintenance program based on condition monitoring as a primary tool. We will now explain the types of failure modes you can expect and how to detect them in the early stages.

Failure mode overview

Industrial fan failure modes

Bearing failure

Bearing failures are the single most common reason for fan malfunction, responsible for 35 – 45% of all industrial fan breakdowns.

Bearings are generally incredibly stable when they operate in perfect conditions. Still, they quickly become vulnerable when conditions are sub-optimal, such as lubrication errors, misaligned axles, dirt in the bearings, excessive vibrations, or extreme temperatures.

Lubrication issues are the primary cause of error. Too much lube, too little lube, or the wrong lube—either way, it will lead to heat building up or increased vibrations that damage the bearing. 

Early-stage bearing failures are detected using temperature and vibration monitoring, such as Neuron Vibration RMS, which has both vibration and temperature measurements in the same unit. Separate temperature measurements can also be helpful in some cases.

Imbalance

The second most common cause of fan failure is imbalance, which accounts for about 15 – 20% of failures. Imbalance appears when one of the rotating parts of the fan has issues with its weight distribution. Usually, the fan blades tend to have the highest velocity, but the motor, shaft, and other transmission parts, like belts, might also have imbalance.

Imbalance leads to vibrations that strain the structure and will speed up the aging of the asset, making it malfunction much sooner than necessary. Imbalances are measured over time using trend vibration sensors like the Neuron Vibration RMS. 

Blade damage

The blades are responsible for moving the air forward in a fan by physically pushing the air when the blades rotate.

The blades can be damaged in many ways, such as corrosion or erosion from gases, or just plain mechanical damage from debris.

Damaged or worn blades will impact fan performance. They can be read as changes in pressure, vibration, or motor current, all conditions that can be detected with neuron sensors like Neuron Vibration RMS, Neuron Gauge Pressure, or Neuron Ampere.

Electric drive motor failure

Most fans are powered by electric motors, which are no exception from the laws of physics in terms of maintenance. Electric motors have their own failure modes that should be handled well to secure fan functionality. 10-12% of fan failures can be traced to motor failures or their electric energy supply.

We have created a separate article on electric motor failure modes; you can find it here: Failure modes for electric motors.

Misalignment and shaft failure

When rotating axles are not perfectly lined up, we call it misalignment, and when shafts and couplings fail, it is often traced back to misalignments.

Misalignments put pressure on the bearings and drive motors and shorten their lifespan. They can also lead to broken seals, lubrication leakage into the airflow, or air pressure leakage.

Detection of misalignments is usually done by vibration monitoring with sensors that are sensitive to vibrations in the range of 20 to 500Hz and should be measured on three axes, like the neuron Vibration RMS. 

Blockages

If the fan inlet or outlet is partially or fully blocked, it will stop the fan from doing its job. Blocking outlets can create pressure buildups that can puncture the air channels due to overpressure. Blocking the inlet might lead to the opposite by creating a vacuum that makes the air channels implode. Either way, you want to avoid blockages and, if they happen, be warned about them.

Blockages can be detected by measuring the outlet air pressure and the motor current. What is not intuitive is that an air inlet blockage can create a vacuum in the pump, reducing current consumption but increasing its rpm due to the loss of air resistance. High rpm might lead to catastrophic failures in the fan blades.

To detect blockage, use one or more of the following sensors:

Neuron Vibration RMS, Neuron Gauge Pressure, Neuron temperature, Neuron Ampere

Pressure instabilities

Any system that copes with different pressure zones can experience pressure instabilities, and industrial fans are no exception.

When air is compressed and collapsed through the air channels, it can generate oscillations that move through the air ducts, creating sound and unwanted vibrations, adding stress to mechanical parts and undesirable noise.

Pressure instabilities can be detected by measuring vibrations on vulnerable components and structures using neuron Vibration RMS.

Resonances

Everything that repeats a rotational cycle can be subjected to self-amplifying oscillations. These oscillations depend on the rotational speed and the component’s resonance frequency. 

Avoiding these resonance frequencies is essential for protecting the fan against destructive forces that can shorten the lifespan of asset components like bearings, motors, or axles.

Resonances can be detected using vibration sensors with a high frequency spectrum, like the neuron Vibration RMS or neuron Vibration High temperature RMS

Loose fundament

Most industrial fans are bolted to a foundation to secure their position and function. Sometimes, the foundation or fasteners break, and the fan starts to vibrate violently. This can damage the fan or its surrounding components, leading to catastrophic failure.

The failure mode with loose fundaments can only be detected by monitoring the low-frequency spectrum, like with the Neuron vibration RMS.

Usually, the vibrations start low and increase gradually until the attachments suddenly break.

Damper faults

All rotating equipment produces vibrations that might be transferred to the supporting structure. Vibration dampers, which absorb and remove the vibrations, are usually used to prevent this.

When the failure mode of defect vibration dampers occurs, it leads to excessive and potentially destructive vibrations on the fan structure or its supporting structure. 

Defect dampers can be detected by monitoring the vibrations over time. The vibration signals usually increase slowly over time as the dampers wear, and can easily be monitored and detected by using Neuron vibration RMS.

General wear and tear

Most industrial fans that are correctly installed and quality-made will keep turning for many years without any failures, but everything has an end, even under perfect circumstances. To be prepared, it can be useful to install hour counters (Neuron Hour counters) that count the exact number of hours the fan has run. This can be used to calculate the remaining useful lifetime RUL and prepare for replacement without a lot of stress and downtime.

Industrial Fan Failure Modes FAQ

What are the most common causes of industrial fan failure?

Common causes include inadequate maintenance, improper installation, environmental factors (like dust, humidity, extreme temperatures), mechanical wear and tear, electrical malfunctions, and misaligned or loose components.

How does inadequate maintenance contribute to failure?

Lack of routine checks, improper lubrication, and infrequent cleaning can cause premature wear, increased friction, and eventual breakdown of components such as bearings and blades.

What installation issues can lead to fan failure?

Improper installation, such as unbalanced mounting, incorrect wiring, or using the wrong wire size, can result in excessive vibration, electrical faults, and mechanical stress.

How do environmental factors affect fan reliability?

Dust can clog and unbalance blades, humidity can cause corrosion, and extreme temperatures can damage motors and materials. Fans in harsh environments may need special coatings or materials to withstand these conditions.

What electrical issues can cause failure?

Frequent voltage fluctuations, incorrect wire or belt sizing, fusing issues, and loose electrical connections can all lead to operational failure or damage to the motor.

How can inadequate airflow cause problems?

Due to clogged filters, misaligned blades, or blocked inlets/outlets, restricted or insufficient airflow can reduce performance and overwork the fan, leading to overheating and wear.

What are the key industrial fan failure mode signs to watch for?

• Unusual noises or vibrations
• Drop in airflow or performance
• Overheating components
• Visual signs of wear, corrosion, or damage

How can industrial fan failures be prevented?

• Schedule regular maintenance and inspections
• Ensure correct installation and alignment
• Use proper materials for harsh environments
• Monitor for early signs of wear or malfunction
• Address electrical and airflow issues promptly