Seals in mining, minerals and cement: why they decide uptime
A seal is a cheap part with an expensive failure. Reported figures put about one bearing failure in five down to sealing, and an unplanned stop can cost several times a planned one.
A small part with a large effect
A seal does two jobs at once: it keeps lubricant in, and it keeps dust, slurry and water out. In a quarry, a mill or a kiln line both jobs are hard, and when either one fails the bearing behind the seal pays for it. Seals are often treated as a consumable. In these industries they are better treated as part of the bearing arrangement.
Figures worth knowing (published, indicative)
| Figure | What it says | Source type |
|---|---|---|
| About 20% of bearing failures | Linked to sealing problems: lubricant escaping, or contamination getting in | Reported from a bearing manufacturer's investigation data |
| 30 to 50% of operating cost | Maintenance share of a mine's total operating cost | Published industry estimate |
| 3 to 5 times | Typical cost of an unplanned stop compared with planned maintenance | Reported by a seal manufacturer |
| 76% of accidents | Share of mining workplace accidents that happen during maintenance work | International Labour Organization figure quoted in industry literature |
What makes these sites hard on seals
- Heavy dust, slurry and wash-down water
- Very large equipment, with shafts and trunnions up to several metres across
- Wide temperature range, from freezing sites to kiln-side heat
- High torque and shock loads, which move shafts and housings
- Limited access, so every seal change means a long strip-down
The usual paths from seal trouble to downtime
- Dirt gets past a worn lip or an old felt and damages the bearing
- Oil or grease leaks out and the bearing runs short of lubricant
- The seal ages early because of abrasion or heat and is replaced too often
- Repeated stops for seal work cut into planned production
- A leak creates a slip, fire or environmental problem
Why safety belongs in the seal decision
A seal that lasts the full maintenance cycle means fewer jobs in dusty, hot or confined places. Fewer jobs means fewer chances for an accident during maintenance, and less lubricant spilled onto the ground. Choosing a seal to match the maintenance interval is a safety decision as well as a cost one.
How to use this section
- Start with the process map for your industry to see which duty applies to which machine
- Read the application stories to see what has worked on real problems
- Check the seal families table before specifying a replacement
- Use the failure-mode guide when a seal has already failed