Sugar Mill Roller Journal Lubrication: Grease, Feed and Season Checks

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A sugar mill tandem presses cane between heavy rollers, mill after mill, for the whole crushing season. Each roller's journals carry very high loads from the hydraulic loading on the top roller, turn slowly, and sit in an environment full of cane juice, imbibition water and bagasse. If the lubricant film fails, a journal can score and overheat within hours, and the whole tandem stops. That is why roller journal lubrication is the single most important lubrication job in a sugar factory.

Why roller journals are so demanding

• Very high load at slow speed. Slow rotation means the lubricant cannot build a thick oil wedge. The journal relies on the lubricant's film strength and extreme-pressure performance.
• Plain bearings. Most mills run their roller journals in plain bronze bearings (often called brasses), which need a constant supply of lubricant.
• Juice and water. Cane juice and imbibition water try to wash lubricant out and carry grit in.
• Heat. Journals run warm under load; many mills water-cool the bearings.

What the lubricant must do

A calcium sulfonate complex grease meets many of these needs: it combines natural EP performance, exceptional resistance to water wash-out, inherent rust protection and stability at temperature. Always follow the mill maker's specification and the lubrication system the mill was designed for.

The feed must never stop

Roller journals are usually fed by a centralised automatic lubricator through distribution blocks and long lines. The rule during the season is simple: lubricant must reach every journal all the time.

• Check the lubricator is stroking and the reservoir is filled at every shift change.
• Watch for blocked lines and distribution blocks; a line that stops moving grease means a journal running dry.
• Keep spare lubricator parts and hoses at the mill.
• Refill only from clean, closed containers; grit in the reservoir ends up in the journals.

Watch temperature every shift

Measure each journal's temperature with an infrared thermometer every shift and write it down. A sudden rise on one journal points to a feed problem, water or grit contamination, a cooling water failure or overload. Act on the trend before the bearing scores.

Keep juice and water out

• Maintain the seals and guards around journals.
• Do not direct wash-down hoses at the journals.
• Keep drains clear so juice does not pool around the bearings.

Mill drives and gearing

• Open gears and pinions on mill drives and cane carriers need an adhesive open gear compound applied by spray or brush. Clean off old, dirty compound before the season and check the tooth contact pattern regularly.
• Enclosed gearboxes need EP gear oil of the grade the maker specifies; hot, heavily loaded mill drive gearboxes benefit from a synthetic PAO oil that runs cooler and lasts longer. Our guide to industrial gear oil grades explains the choice.
• Carrier chains need a penetrating chain lubricant away from the sugar, and food-safe practice where lubricant could reach sugar.

Off-season checklist

The off-season decides how the next season runs.

1. Inspect the bearings (brasses) and journals for scoring and wear.
2. Clean and flush the lubrication lines; test every line for flow.
3. Overhaul and test the automatic lubricator.
4. Drain, flush and refill gearboxes; inspect gears.
5. Clean open gears and check tooth contact.
6. Test and, if needed, purify the turbine oil of the cogeneration and mill drive turbines.
7. Stock the season's grease, gear oil and spare belts, stored clean and dry; see our storage and handling rules.

For the full range of sugar mill lubricants, including turbine oil for cogeneration, see our page on sugar mill lubricants.

Frequently asked questions