Mill Stand Roll Housing Bore Reclamation

The challenge

A rolling mill stand carries heavy, shock-loaded forces through the roll housing bores and the liner seats that locate the bearings. Over time those surfaces wear and fret, the bores go out of round, and the seats lose their grip. With the fit gone slack, the bearings shift under load instead of sitting fixed, which knocks the roll out of position, accelerates wear, and shows up as off-gauge product and chatter. Left alone, the movement keeps pounding the housing oversize, and the usual fix means line-boring or replacing a heavy casting that is slow to source and hard to pull.

The Belzona approach

The worn surfaces are taken back to sound metal and rebuilt in place rather than machining the housing oversize. With the bores and liner seats blasted clean and profiled, a 1000 Series composite rebuilds the lost and fretted metal cold so the casting sees no heat or distortion. Conforming support is then cast directly against the bearing or liner, released so the support takes the exact shape of the mating part and carries the load across the full contact area. That puts the bearing back in a fixed, fully supported fit so it stops shifting under the rolling forces.

1. Assess and mapThe bores and liner seats are measured to find where they have gone out of round and where the metal has fretted away, establishing what has to be rebuilt.
2. Surface preparationGrit-blasting takes the worn bores and seats back to clean, profiled metal so the rebuild bonds to a sound surface.
3. Cold metal rebuildA 1000 Series composite rebuilds the lost and fretted metal, applied cold so the heavy casting takes no welding heat or distortion.
4. Cast in conforming supportThe bearing or liner is released and support is cast directly against it so the rebuilt seat takes the exact shape of the mating part and bears across the full contact area.
5. Reassemble and return to serviceThe restored fit is checked and the stand reassembled and returned to service so the bearings sit fixed and the roll holds position under load.