What makes conveyors different
A conveyor is not one machine but a chain of many repeating parts: dozens or hundreds of rollers, a belt or chain, pulleys or sprockets, bearings, a drive and a take-up. Because the parts are repeated along a considerable length, wear is spread out and easy to overlook, and one failed component can stop everything upstream.
Conveyors also carry material, and material is messy. Dust, spillage, moisture and product residue are the main enemies. A large share of conveyor maintenance is simply stopping that debris from getting into places where it causes friction, misalignment or corrosion.
This article covers the upkeep tasks themselves. Looking for problems on a regular walk-down is a related but separate activity.
Safe working first
Almost every task below requires the conveyor to be stopped. Under lockout tagout style procedures, energy sources are isolated, locked and checked so that the conveyor cannot start while someone is working on it. Conveyors can also have stored energy: a loaded inclined belt can run backward if a brake is released, and a tensioning system may hold force. Only trained, authorized personnel should do the work, following the manufacturer’s manual, site procedures and local regulations. Guards that are removed for a task must be put back before the conveyor is returned to service.
Lubrication
Bearings in rollers, pulleys, drives and take-ups need the right lubricant in the right amount. Many conveyor rollers are sealed and lubricated for life, in which case the maintenance task is replacement, not greasing. Others, especially larger pulleys and drive bearings, have grease points that need regular attention.
A few principles apply:
- Use the lubricant type the manufacturer specifies. Mixing incompatible greases can break down their properties, so grease selection is not a casual choice.
- Apply the recommended amount. Over-greasing is a common cause of seal damage and overheating, while too little leads to wear.
- Keep grease fittings clean, and wipe them before and after use so dirt is not pushed in.
- Record what was applied and when.
Chains are lubricated differently from bearings. A chain needs lubricant to reach the pins and bushings, where the wear actually happens, and not only the outside of the links. Dry, rusty or stiff chains wear faster and stretch sooner. The exact method and lubricant depend on the chain’s speed, load and environment, so follow the manufacturer’s advice.
Belt care
Belts last longest when they are kept clean, tracked properly and not overloaded or abused. Typical tasks include:
- Cleaning. Removing buildup from the belt surface and the return side, and keeping scrapers and cleaners adjusted correctly. A cleaner that presses too hard wears the belt; one that is too loose lets material carry back and fall off.
- Tension adjustment. A belt that is too slack can slip at the drive pulley, wearing both belt and pulley and sometimes causing heat. One that is too tight overloads bearings and shortens belt life. Take-up settings should follow the manufacturer’s guidance and be rechecked as new belts stretch during their first period of use.
- Tracking correction. A belt wandering to one side is often corrected by small adjustments to rollers or pulleys, but the cause should be found first. Uneven loading, buildup or damaged rollers are common culprits, and repeatedly steering the belt without finding the cause usually just hides the problem.
- Repair of damage. Small cuts and edge damage can sometimes be repaired, while splices that are cracking or separating need attention before they fail under load.
- Skirt and seal care. Replacing worn skirting rubber reduces spillage and dust.
Chain and sprocket care
For chain-driven conveyors, the main concerns are lubrication, wear and tension. Over time, pins and bushings wear and the chain elongates, which can cause it to ride up on the sprocket teeth, and sprockets then wear in a hooked shape. A chain that is replaced while the old sprockets remain may wear out quickly, so many sites replace parts as matched sets where appropriate. Chain drives of this kind generally call for correct tension, aligned sprockets and intact guards.
Rollers and idlers
Rollers that no longer turn should be replaced rather than left to wear flat spots into the belt. A planned approach, such as changing a number of worn rollers in a section during a scheduled stoppage, is typically far less disruptive than emergency replacement. Keep a modest stock of the common roller sizes and bearings so a replacement does not wait on delivery.
Alignment
Pulleys, rollers and the frame should be square to the belt’s path and level in the right places. Misalignment makes belts wander, wears edges and loads bearings unevenly. Drives need alignment too: the motor and gearbox must be properly aligned with the driven shaft, and an incorrect arrangement wears couplings and bearings. Shaft alignment checks are commonly done after any drive work, and on a regular basis for critical conveyors. If the structure itself has moved, because of foundation settlement or impact damage, alignment may need to be re-established from the frame outward.
Drives, gearboxes and electrical
Gear reducers should have the correct oil level and no leaks, and breathers should be unblocked. Motors need clear cooling air paths, so dust must be removed from fins and vents. Check that couplings and drive guards are secure. Limit switches and other sensing devices should be clean and securely mounted, since dirt and knocks can disturb them. Electrical work belongs to qualified personnel.
Cleaning and housekeeping
Clean-up is not a minor task on a conveyor. Spillage at transfer points can bury rollers and bearings, and dust coating motors and drives traps heat. Where the material is combustible dust, such as some food and wood products, cleaning practices carry extra importance and should follow the site’s hazard assessments. Use methods approved for the material and the area; compressed air blowdown, for example, can raise dust clouds and is not appropriate everywhere.
Planning and records
Turn the tasks above into a schedule with clear owners and intervals, and record what was done and what was found. A short list of parts commonly replaced, such as rollers, scrapers, skirting and belt fasteners, helps ensure that they are available. Review the schedule when the product, throughput or environment changes. Records of how long belts and chains actually last also help with the replacement decision, since a component that wears out much earlier than expected usually has a cause worth investigating.
This is general information, not engineering advice for a specific conveyor. Always follow the manufacturer’s maintenance instructions and your site’s procedures.