Screw Conveyors: Wear, Bearings and Maintenance is a practical reference on how a rotating helical screw (auger) moves bulk solids through a trough or tube, where it wears, and how to keep the flighting, bearings, seals and drive in service. A screw conveyor looks simple, but its reliability depends on a small number of components that degrade predictably once you know what to watch.
A screw conveyor consists of a helical flight welded to a central pipe or shaft, turning inside a U-shaped trough or a closed tube. As the screw rotates, the flight pushes material along the axis toward the discharge. Long conveyors are built from several screw sections joined by coupling shafts, with intermediate hanger bearings supporting the joints. The drive is normally mounted at the discharge end so the screw runs in tension rather than compression, which reduces the tendency of the pipe to buckle or deflect.
Trough loading is defined as the fraction of the cross-section occupied by material. Standard design loadings under CEMA (Conveyor Equipment Manufacturers Association) practice are 15, 30 and 45 percent, chosen by how abrasive, sluggish or free-flowing the material is. Running above the design loading is a common root cause of overload, hanger-bearing damage and premature wear.
Abrasive materials such as sand, ash, cement, grain hulls and mineral ore attack two surfaces: the outer edge of the flight and the bottom of the trough on the carrying side. Wear is rarely uniform. It concentrates where material is dragged hardest, so the outer flight diameter shrinks and the trough bottom thins. Both change the running clearance, which reduces throughput and lets material recirculate instead of advancing.
Hanger bearings sit inside the trough at each coupling joint and are the most maintenance-sensitive part of the conveyor. They run in the material stream, so they see dust, moisture and abrasives that no external bearing would tolerate. Bearing material is selected to match the conveyed product: hard iron or bronze for general duty, oil-impregnated bronze or hardened surfaces for abrasives, and non-metallic types such as UHMW or nylon where contamination of the product must be avoided.
Because they operate submerged in material, hanger bearings need a defined lubrication and inspection interval. Where grease is used, purge enough to flush contaminated grease out through the seal. For guidance on selecting and scheduling this, see our overview of lubrication regimes. A seized hanger bearing quickly wears the coupling shaft, then shears coupling bolts, so early detection matters.
The two end bearings, at the drive and tail ends, are mounted outside the trough and are easier to service. The screw generates an axial thrust load, so a thrust bearing is located at the discharge end to carry it and to keep the screw in tension. Shaft seals, typically packing glands or lip seals, sit where the shaft passes through the trough end plates. Leaking seals let product escape and let contaminant and moisture into the end bearing, which is a frequent cause of end-bearing failure. Inspect seals for leakage and dust tracks, and keep the trough end plate clean so the seal is not packed with product.
| Failure mode | Likely cause | Check |
|---|---|---|
| Reduced throughput | Flight edge and trough wear increasing clearance | Measure flight OD and trough-bottom thickness against as-built |
| Hanger bearing seizure | Missed lubrication, abrasive ingress, wrong bearing material | Temperature and noise at hangers; inspect coupling shaft for scoring |
| Sheared coupling bolts | Seized bearing or jam raising torque on the joint | Torque check; inspect bolts and coupling shaft fit |
| Seal leakage / end-bearing failure | Worn packing or lip seal; product packing at end plate | Look for product tracks and moisture at end bearings |
| Overload / motor trip | Trough loading above design; material build-up or choke | Verify fill level vs 15/30/45% design; check inlet and discharge for blockage |
| Jamming / material build-up | Sticky or wet product, foreign object, over-feeding | Inspect trough and flight for caking; confirm feed rate control |
Overload and jams share the same warning sign: a sudden rise in drive torque or motor current. Fit a shear pin, torque limiter or current monitor so a jam stops the drive before it shears couplings or bends the screw. Sticky and hygroscopic materials build up on the flight and trough and reduce free area; wet cleaning or a shift to a ribbon or cut-flight screw may be needed. Never clear a jam by hand until the drive is locked out.
The gearmotor, its coupling to the screw and the drive-shaft alignment round out a maintenance route. Check oil level and temperature in the gear reducer, listen for bearing noise, and confirm the drive coupling and any belt or chain are tensioned and aligned. Misalignment between motor and reducer adds vibration and bearing load; the principles are covered in our guide to coupling alignment. Where a screw conveyor feeds a vertical lift, coordinate its inspection with the adjacent bucket elevator so both are serviced in one shutdown.
A CMMS turns these one-off checks into a repeatable schedule with wear-measurement history per screw section. Book a Fabrico demo to see how hanger-bearing routes and flight-wear trends can be tracked in one place.
Intervals depend on the bearing type and the material conveyed. Bearings running in abrasive or wet product often need weekly or per-shift attention, while lightly loaded units may run monthly. Set the interval from the bearing manufacturer's guidance and shorten it if grease comes out contaminated.
Replace or hardface when the flight has lost roughly 10 to 15 percent of its radial height or when the clearance to the trough has grown enough to cut throughput noticeably. Track the outside diameter over time rather than judging by eye.
Repeated bolt shearing usually points to something raising torque at that joint: a seizing hanger bearing, a jam, or a worn coupling shaft with a loose fit. Inspect the adjacent bearing and shaft before simply fitting new bolts.
The thrust bearing is placed at the discharge end so the conveyed material keeps the screw in tension. This reduces buckling and lets the more heavily loaded bearing sit outside the trough where it can be serviced.
Iniciar sesión
Blog