Machine Condition Monitoring Case Studies

Representative hot-strip mill motor and gearbox drive train — Representative imageGBX-2 · gearbox input bearing

Observed symptom

A bearing-frequency family rises at the gearbox input point during steady rolling load. One trend starts the investigation; it does not finish it.

Required context

Motor, gearbox and process state share one operating window before each channel is compared with its reference.

Steel · illustrative application

Input-bearing evidence under matched load.

GBX-2 · gearbox input bearing

Swipe or use arrow keys to review five evidence channels

Vibration analysis
Localizes
An outer-race family and its harmonics rise at the input point under matched speed and load.
IR thermography
Co-locates
The same housing region is warmer than its matched-load reference under a controlled view.
Ultrasonic monitoring
Co-locates
Repeat impacts rise at the same documented point above its local operating baseline.
Motor current analysis
Not supplied
Drive-train torque modulation could not be tested. This absence does not prevent the local bearing review.
Oil analysis
System corroboration
Sump iron is rising. It supports a gearbox-system wear hypothesis but cannot identify the bearing or wear mechanism.

Correlated assessment

Three local channels co-locate at the GBX-2 input bearing. The sump iron trend is consistent with gearbox wear; developing outer-race distress remains the leading hypothesis.

Evidence gap

Direct inspection confirmation is not yet available; bearing geometry, sensor setup and lubrication delivery still require field verification.

What would change the decision

Repeatable bearing-family growth at matched load and inspection confirmation would strengthen the hypothesis. Loss of repeatability or movement with process state would weaken it.

Recommended action

Verify lubrication and setup, shorten monitoring cadence, and plan inspection by asset criticality.

Assess a similar machine

Representative boiler-feed pump and motor train in a power plant — Representative imageBFP-1 · high-speed drive-end bearing

Observed symptom

High-frequency energy climbs at the pump drive end during low-flow operation. The initial alert looks bearing-related until process state is added.

Required context

Pump, coupling, motor, valve position, flow and suction condition must share one timeline before a localized fault is inferred.

Power generation · illustrative application

A bearing alarm challenged by process context.

BFP-1 · high-speed drive-end bearing

Swipe or use arrow keys to review five evidence channels

Vibration analysis
Challenges
Broadband energy follows the low-flow operating window; no stable bearing-frequency family persists under order tracking.
IR thermography
Challenges
The drive-end housing remains inside its matched steady-state spread, with no repeatable local hot region.
Ultrasonic monitoring
Process-linked
Level rises across the pump casing during the same valve state and does not remain confined to the bearing point.
Motor current analysis
Not supplied
Motor-load modulation could not be compared with the low-flow event. It would add drive context, not localize a pump bearing.
Oil analysis
System context
Wear markers remain inside their comparable history; the shared circuit does not currently corroborate a localized wear hypothesis.

Correlated assessment

Available evidence currently favors operating-point hydraulic excitation over localized bearing distress. Cavitation or recirculation remains a hypothesis, not a confirmed cause.

Evidence gap

Suction pressure, flow and valve position are not yet synchronized with the condition data at sufficient resolution.

What would change the decision

A repeatable bearing-family pattern that persists after the hydraulic condition is controlled would strengthen the bearing hypothesis. Direct tracking with flow or valve state would weaken it.

Recommended action

Capture those process variables with vibration, verify suction conditions and repeat across the operating map before planning bearing work.

Assess a similar machine

Representative clinker conveyor motor and gearbox drive — Representative imageCV-7 · gearbox output bearing

Observed symptom

Intermittent impacts appear under load. Belt events and structural transfer can imitate a low-speed bearing fault.

Required context

The available route data identifies the gearbox region, but it lacks the synchronized output-speed and process-event reference needed to separate the causes.

Cement · illustrative application

An impact pattern that is not yet localizable.

CV-7 · gearbox output bearing

Swipe or use arrow keys to review five evidence channels

Vibration analysis
Unresolved
Impacts are strongest near the output housing, but repeatability against shaft order cannot be tested without a tachometer reference.
IR thermography
Challenges
Available load-matched images show no persistent output-housing differential beyond the inspection spread.
Ultrasonic monitoring
Unresolved
Repeat impulses are present at the housing, but structurally transmitted process shock has not been excluded.
Motor current analysis
Not supplied
Torque modulation from changing belt load could not be tested. Motor current would add train-level context, not identify the impact source.
Oil analysis
Separate concern
Contamination is rising in the sump. It warrants correction but does not identify the impact source or mechanism.

Correlated assessment

The evidence does not yet support output-bearing distress. Process shock and structural transfer remain credible; rising contamination is a separate system-level concern.

Evidence gap

No synchronized tachometer or process-event reference was captured with the impacts.

What would change the decision

Shaft-order repeatability and a stable near-to-far measurement gradient would strengthen the bearing hypothesis. Synchrony with belt events or a distributed response would weaken it.

Recommended action

Capture output speed and belt-event markers, repeat near- and far-side measurements, then reassess before scheduling bearing work.

Assess a similar machine

Context changes the answer.

Input-bearing evidence under matched load.

A bearing alarm challenged by process context.

An impact pattern that is not yet localizable.

Start with the machine that is changing.