Sugar Mill Roll and Screen Rebuild

The challenge

A sugar mill roll journal and the screen plate around it take a hard beating. The acidic juice corrodes the steel while the constant flow of bagasse abrades it, so the journal wears undersize and the screen plate thins and roughens. As the journal loses metal, the bearings no longer sit true and clearances open up, which lets the roll move where it should run tight. A thinned screen plate stops doing its job and gets close to failing. If the journal and the screen are not brought back, the mill cannot hold setting through the grinding season, and pulling and replacing those components mid-season is the kind of downtime a mill cannot afford.

The Belzona approach

Work starts with blasting the journal and the screen areas back to clean, profiled metal so the repair has something sound to bond to. The worn journal is rebuilt cold with a Belzona 1000 Series composite, building back enough material that it can be dressed back down to size for the bearings. Where the screen plate has thinned, it is built back up the same way. Once the metal is back, the rebuilt surfaces are protected against the acidic juice and the bagasse abrasion so they hold their shape. The roll goes back carrying its bearings true, and the screen carries on through the grinding season without swapping in new components.

1. Assess and measureThe journal and the screen plate are checked to map where the juice and the bagasse have taken metal and how far the journal sits undersize.
2. Blast to clean metalGrit-blasting takes the journal and the screen areas to a clean, profiled surface so the composite and the protective layer bond to bare steel.
3. Rebuild the journal coldA Belzona 1000 Series composite rebuilds the worn journal, worked cold so the roll sees no heat distortion, leaving enough material to dress back to size.
4. Build up the screen plateThe thinned areas of the screen plate are built back up with composite to restore the surface the juice and bagasse had worn away.
5. Protect and return to serviceThe rebuilt journal and screen are protected against the acidic juice and bagasse abrasion, and the roll returns so it carries its bearings true through the season.