Drum Shell Liner Plate

Function

The liner plate's primary duty is to shield the drum shell from abrasive wear generated when sharp aggregate tumbles and slides along the drum's inner circumference during each production cycle. Without effective liner protection, the drum shell wall thins, weakens and ultimately fails — a catastrophic repair requiring crane mobilisation and extended downtime. Well-maintained liner plates sustain drum roundness and heat retention, preserving drying efficiency and consistent aggregate outlet temperatures. Their thermal mass also buffers short-term burner fluctuations, contributing to blend-temperature consistency across the production shift.

Construction & quality

Fabricated from high-manganese-chromium alloy steel (Mn 12–14 %, Cr 1–2 %) with a Brinell hardness of 380–420 HBW at the working surface. Plates are investment-cast or hot-rolled and furnace stress-relieved. Mating faces are machined to ±0.5 mm flatness to ensure tight shell contact and prevent hot-spot bridging. Countersunk bolt holes accept high-temperature M20 Grade 10.9 fasteners. Plate edges are chamfered 15° to interlock adjacent segments and resist lift-off under load. Thickness is graded — heavier at the inlet zone (12 mm), standard gauge toward the outlet (8 mm) — to match the actual wear gradient inside the drum. Working surfaces are shot-blasted to Sa 2.5; no paint finish is applied to allow visual wear monitoring in service.

When to replace

• Plate surface thickness at or below 4 mm remaining, measured by ultrasonic gauge through bolt access holes.
• Cracking or spalling at plate edges, particularly on burner-end panels exposed to peak temperatures.
• Loose or missing fasteners causing audible rattle during drum rotation.
• Uneven aggregate outlet temperatures suggesting localised hot spots from failed plate-to-shell contact.
• Unexplained rise in fuel consumption at constant feed rate — indicates loss of drum thermal efficiency.