Rolling-mill hydraulics may be asked to adjust force and position repeatedly while exposed to scale, heat and water. A generic annual seal replacement schedule does not address the sources of premature wear. Maintenance should be tied to the function of each cylinder and the evidence seen in operation.
Match inspection to the mill station
A roll-gap control axis differs from a lift or clamp actuator in response and positioning needs. Bosch Rexroth describes rolling-mill systems with functions such as automatic gap control. For a critical axis, inspect feedback quality, pressure behavior and seal condition together. In less precise auxiliary service, mechanical alignment, exposed-rod damage and leakage may be the dominant checks. The correct interval depends on duty and plant history.
Engineering checks
- Trend oil cleanliness and water entry near the mill line.
- Inspect wipers and rod finish after scale or washdown exposure.
- Check mounting pins, guide alignment and vibration.
- Review pressure peaks during reversals and stops.
- Record position error and leakage before and after service.
Common mistake to avoid
Replacing seals without documenting the original wear pattern can erase the evidence of side load, wrong fluid or pressure spikes. Keep failed parts for inspection.
Data to send with an inquiry
- Cylinder identification and process station.
- Operating pressure, temperature, cycle and fluid.
- Recent oil analysis and fault history.
- Available shutdown window and spare-part requirements.
Use an inspection record tied to each serial number so maintenance changes can be evaluated against actual reliability. For related selection guidance, see our metallurgical cylinder product page.
Technical references: Bosch Rexroth metallurgy solutions; Parker cylinder bushing maintenance bulletin. Cover: original conceptual schematic, not a product photograph.