Unplanned stops in rolling mills

The one action to reduce unplanned stops, grease use, and re-greasing operations. And what to do next.

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Why unplanned stops matter

Planned maintenance stops are scheduled around production. Unplanned stops are not. A bearing seizure, a gearbox running above temperature, or contamination breaching a bearing housing can force an immediate halt. The effects are direct: lower tonnage, delivery risk, reduced safety margins, and maintenance teams diverted from improvement work to incident response. The cost per minute is high and visible to management.

Typical contributors

Unplanned downtime is usually a combination of factors: mechanical wear, misalignment, inconsistent lubrication, contamination, sensor or control faults, electrical disturbances, and material-handling interruptions. Some events are preventable, and many are predictable with adequate monitoring. The practical goal is twofold: reduce the number of unplanned stops and the time to restart. When a stop happens, use the window to prevent recurrence.

Start here: replace open bearings with sealed bearings

Where should you begin? What is the fastest, high-impact change? According to Benjamin Michael, Account Manager with experience from many rolling-mill customers, there is one recommendation he always makes first:

“Replace open bearings with sealed bearings on assets with repeat failures and heavy contamination.”

In rolling-mill environments, sealed bearings block ingress and retain clean lubricant. This addresses two dominant causes of bearing failure: contamination and insufficient lubrication. It also reduces the need for re-greasing and, in many applications, enables fully relubrication-free operation. Thanks to the same dimensions of open and sealed bearings, the switch is very easy and requires no significant rebuild or redesign in most cases.

Why sealed bearings are effective

Ingress control: Contact seals resist scale, moisture, and dust from entering the bearing.
Lubricant retention: Grease is kept in the bearing during operation, reducing the risk of leakage.
Fewer planned lube interventions: Less re-greasing time on the bearing; cleaner downstream systems.
Relubrication-free operation: In suitable applications, sealed designs and correct grease selection enable operation without re-greasing.

What to do next

Beyond sealed bearings, SKF offers several solutions to make the invisible visible and the unpredictable manageable.

1. See the signals before they become stops

SKF offers a wide range of condition monitoring equipment, from handheld devices for manual weekly or monthly tracking to automated systems that can keep critical assets under control every second. These systems pick up vibration spikes, temperature anomalies, or lubrication changes before they escalate into downtime. With real-time alerts and historical trend data, your teams can schedule interventions proactively.

Condition monitoring can also extend component life by revealing early signs of distress, before a bearing fails or becomes damaged beyond repair. This allows for earlier scheduled removal, reducing the risk of in-service failure and increasing the chance that the bearing can be remanufactured after inspection.

2. Let the experts read the data for you

3. Protection from the first minute of operation

4. Shift to performance-based maintenance

5. Choose the right grease, in the right amount

Lubrication might seem like a routine task, but it’s one of the most overlooked causes of failures. Choosing the correct grease for your specific application and applying it in the optimal quantity can have a major impact on reliability.

Over-greasing can cause overheating or seal damage, while under-greasing increases friction and accelerates wear. SKF’s lubrication expertise helps ensure that every asset gets precisely what it needs. The result is smoother operation, fewer interventions, and extended component life.

6. Remanufacture bearings before replacement is necessary

Five actions to implement

Where do you start? Right where you are. Here are five things you can do to get going:

Go sealed. Retrofit sealed bearings on “bad actors”. Prioritize stands and high-contamination positions with repeat failures or frequent re-greasing.
Get control. Start condition monitoring on one critical train end-to-end. Combine route-based measurements with an online node on the highest-risk stand or gearbox. Start with simple alarm rules; refine with live data.
Remanufacture more. Adopt a bearing decision matrix (run/reman/replace). Tie decisions to measured conditions so units are captured early enough for remanufacturing.

Apply lubrication discipline. Specify grease by load, speed, temperature, and contamination. Move critical points to automatic systems. Define intervals and quantities explicitly.
Seal even more. Plan an upgrade with an external sealing arrangement. Combine sealed bearings with housing/shaft seals in the harshest positions.

Get help to get started

To reduce the frequency of unplanned stops and to shorten and use the remaining stops more effectively, start by sealing out contamination, detecting early, and acting with precision. SKF offers a complete solution: bearings and seals, condition monitoring and diagnostics, lubrication systems, precision mounting and alignment, and remanufacturing.

Contact SKF to identify priority retrofit positions and design a sealed bearing and condition monitoring rollout for your mill.