Cement Screw Conveyor Flighting

Function

Flighting wear reduces effective pitch depth, lowering conveying efficiency and progressively increasing the fill cycle time required to deliver a given cement mass to the weigh hopper. Severe wear allows the flighting edge to contact the trough bore, generating metallic iron contamination of the cement stream and risking conveyor stall under load — which trips the drive motor and interrupts batching. Maintaining proper flighting-to-trough clearance (nominally 5–8 mm) ensures design throughput rates in the range of 15–80 tonnes per hour are sustained throughout the conveyor's service life.

Construction & quality

Flighting is cold-formed from 6–10 mm flat-rolled carbon steel (S355 or equivalent) and continuously fillet-welded or plug-welded to the central pipe shaft. Edge induction hardening or chromium carbide hard-facing overlay (WC content 55–60 vol%, hardness HRC 58–65) is standard for supplementary cementitious materials including fly ash and GGBS, which are more abrasive than OPC. Shaft pipe is Schedule 40 or 80 mild steel, 102 mm or 114 mm OD. Complete assemblies are dynamically balanced where the conveyor length exceeds 6 m. End journals are machined for the bearing and seal housings.

When to replace

• Reduced cement delivery rate at constant drive speed, requiring shaft speed increase to compensate
• Metallic scraping or grinding noise from the conveyor trough during operation
• Iron-stained cement reaching the weigh hopper or discolouration in silo sample
• Flighting edge worn more than 30% of original thickness on visual measurement
• Conveyor motor tripping on overload under normal cement density and feed rate