Pugmill Trough Liner Plate

Function

Trough liner plates define one side of the mixing gap — the critical clearance between the rotating paddle tip face and the stationary liner surface. As the liner wears, the gap grows, reducing shear intensity and aggregate coating efficiency. Beyond approximately double the new clearance the mixer can no longer achieve the target coating value within the design cycle time, forcing longer mixing times that reduce plant batch rate and TPH throughput. More critically, fractured liner panels or liner bolts lost into the mix introduce steel fragments into the batch — a serious quality defect requiring rejection of the batch and a full mixer inspection before restart.

Construction & quality

Cast from high-chromium white iron (25–28% Cr, 2.5–3.0% C, hardness 550–650 HBW) for maximum abrasion resistance, or fabricated from AR500 quenched and tempered steel plate (500 HB). Cast sections are profile-ground on a surface or cylindrical grinder to conform to the trough radius to ±1.0 mm, ensuring consistent clearance across the full paddle tip set. Plate thickness new: 20–30 mm. Bolt holes are drilled and counter-bored from the trough exterior so all fastener heads are flush with or below the structural trough face, not the liner wearing face. Minimum replacement thickness: 8–10 mm.

When to replace

• Liner thickness below 10 mm as measured by ultrasonic thickness gauge at inspection ports
• Tip-to-liner clearance exceeding 20 mm (combined liner and tip wear), verified by feeler gauge through the inspection plate
• Fractured liner panel detected by hollow sound on percussion or visible crack at a panel joint during shutdown inspection
• Mixing cycle time increasing beyond the target recipe value for the same aggregate type and temperature
• Loose or missing liner bolts — detected by rattle during mixing or metal fragments found in discharged batch