Top 5 Faults Detected in Mining & Aggregates Operations

In the mining and aggregates industry, equipment must operate continuously in harsh conditions while meeting demanding production targets. Many sites rely on assets that have been in service for decades, leaving them vulnerable to wear, fatigue, and gradual degradation. 

When these issues go undetected, even minor defects can quickly turn into costly, unplanned downtime. In mining operations, downtime can cost as much as $180,000 per hour, making early detection critical. Predictive maintenance (PdM) gives teams the insight to identify and address problems early, reducing repair costs and minimizing disruption to operations. 

Data from PdM programs across mining and aggregates facilities reveals a clear pattern. The following five fault types are the most commonly detected and offer the greatest opportunity to intervene before failures occur. 

1. Rolling Element Bearing Faults 

Rolling element bearings are some of the most critical and failure-prone components in mining equipment. They are found throughout the operation in conveyors, crushers, fans, and motors, and their health directly impacts overall machine performance. Bearings endure extreme loads, constant vibration, shock forces, and abrasive contamination, making them highly susceptible to accelerated wear. 

In mining environments, additional factors compound the risk: dust, moisture, and process material can infiltrate seals, while misalignment, imbalance, or degraded lubrication further stress components. Because bearings are often hidden and difficult to inspect visually, undetected early-stage wear can lead to costly, unexpected failures. 

Common indicators include: 

• Increasing vibration at characteristic bearing frequencies 

• Early-stage defects on inner race, outer race, or rolling elements 

Why early detection matters: 
Bearing faults typically develop over time. Detecting them early allows teams to plan bearing replacements during scheduled outages rather than responding to sudden failures that can damage shafts, housings, and surrounding components. 

Bearing failures can also create serious safety hazards, such as material ejection, uncontrolled machinery movement, or the need for workers to enter confined or hazardous areas to perform emergency repairs. Early detection through predictive maintenance protects both the reliability of critical assets and the safety of personnel, turning a potentially dangerous situation into a controlled, low-risk maintenance activity. 

2. Imbalance 

Imbalance occurs when the center of mass of a rotating component does not align with its axis of rotation. In mining and cement operations, imbalance is especially common on large fans, crushers, conveyors, and pulleys. 

Common causes include: 

• Material buildup on fan blades or rotating surfaces 

• Uneven wear or erosion 

• Broken or missing components 

• Improper repairs or component replacement 

In environments where dust and process material are constantly present, buildup on rotating components is a frequent contributor to imbalance. Over time, even small amounts of accumulated material can significantly increase vibration levels and accelerate wear across connected components.

Unchecked imbalance increases stress on bearings, shafts, couplings, and foundations. It also drives higher energy consumption and can shorten asset life significantly. 

Case Study: Detecting Imbalance Due to Material Buildup 

Challenge 
A global cement manufacturer needed a cost-effective way to monitor tier-II critical assets at its flagship North American plant. Wired systems were too expensive, and route-based monitoring was not feasible for many machines, leaving key assets at risk of undetected failure. 

Solution 
The plant implemented a continuous wireless predictive maintenance solution, supported by an AssetWatch® Condition Monitoring Engineer (CME). 

Soon after deployment, the CME detected elevated vibration on a separator fan running on the facility’s most profitable line. Increased vibration at running speed in the horizontal and axial directions indicated imbalance, and non-synchronous vibration suggested a developing bearing issue. 

Inspection confirmed material buildup on the fan. After cleaning, vibration dropped significantly. Early identification of the bearing fault allowed the team to schedule replacement months before failure. 

Result 
The corrective action prevented an estimated $120,000 in lost production and repair costs. 

Within six months, the plant achieved a 57X return on investment, and the solution has since been expanded to six facilities to reduce unplanned downtime and increase productivity. 

Why early detection matters: 

Imbalance often begins as a manageable issue, particularly when caused by buildup or early component wear. When identified early, corrective actions such as cleaning, rebalancing, or minor repairs can be completed quickly and at low cost. 

If left unaddressed, imbalance accelerates bearing damage and can lead to cascading failures. In high-throughput mining and cement operations, early detection protects production continuity and delivers measurable financial returns. 

3. Misalignment 

Misalignment happens when connected components, such as motors and gearboxes, are not properly aligned. In mining environments, alignment can degrade over time due to foundation movement, thermal growth, or improper installation. 

Typical symptoms include: 

• Elevated axial and radial vibration 

• Increased coupling and bearing wear 

Why Early Detection Matters: 
Even slight shaft misalignment increases radial and axial loading on bearings, couplings, and seals. These elevated forces lead to higher vibration amplitudes, increased frictional heat, lubricant film breakdown, and accelerated fatigue of rotating components. Early detection through vibration analysis or precision alignment verification allows corrective action before stress concentrations result in irreversible component damage and unplanned failure. 

4. Rotating Looseness 

Rotating looseness refers to excessive clearance or movement within rotating components, such as loose bearings on shafts or worn fits. 

Common contributors include: 

• Wear from prolonged vibration 

• Improper installation or insufficient torque 

• Fretting or fatigue damage 

Why Early Detection Matters: 
Rotational looseness introduces mechanical instability at the foundation, bearing housing, or structural interface, allowing relative movement between components that should remain rigidly constrained. This condition often produces non-linear and intermittent vibration signatures, impact modulation, and harmonic distortion, all of which accelerate fatigue in fasteners, housings, shafts, and bearings. As clearances increase, energy transfer becomes unpredictable, amplifying dynamic loads and promoting crack initiation and fretting damage. Early detection enables corrective action before structural integrity is compromised, preventing cascading damage and reducing the likelihood of catastrophic failure. 

5. Structural Looseness 

Structural looseness involves unintended movement within a machine’s support structure, mounting points, or foundation. In mining and heavy industrial environments, large rotating assets generate significant dynamic forces. Over time, these forces can loosen bolts, crack welds, degrade grout, or weaken structural supports. 

Because many mining and cement facilities operate aging equipment, foundation integrity and mounting stability can deteriorate gradually. Structural looseness often develops slowly and may go unnoticed until vibration levels increase significantly or secondary damage occurs. 

Common causes include: 

• Loose or broken mounting bolts 

• Cracked welds or fatigued structural members 

• Degraded grout or foundation settling 

• Insufficient structural stiffness 

Structural looseness is particularly problematic because it can amplify other conditions such as imbalance or misalignment, making accurate diagnosis more difficult and accelerating overall machine degradation. 

Case Study: Preventing Kiln Downtime Caused by Structural Looseness