Mixer Shaft End Oil Seal

Function

Seal failure is among the most common causes of premature bearing failure in twin-shaft mixers. Slurry ingress rapidly contaminates bearing lubrication, generating localised heat and accelerated Brinell indentation on ball or roller raceways. Conversely, lubricant loss starves the bearing of the oil film required to separate rolling elements under the high radial and axial loads imposed by aggregate resistance on the mixing arms. An intact, correctly specified seal maintains design bearing service intervals — protecting an assembly worth many times the seal's own cost.

Construction & quality

Standard supply is a spring-loaded multi-lip seal with PTFE-filled NBR elastomer on the slurry-side lip and standard NBR on the lubricant-side lip. The shaft running surface is specified as minimum HRC 55, either chrome-plated or induction-hardened steel to resist abrasive scoring from any cement particles that breach the outer deflector. Outer casing is pressed carbon steel, zinc-phosphated and grease-packed at assembly. All elastomers are confirmed compatible with OPC and sulphate-resisting cement environments. Seals are manufactured to ISO 6194 or equivalent dimensional standards and individually wrapped for contamination-free storage.

When to replace

• Cement slurry or grey paste visible at the shaft exit point from the trough wall
• Grease or oil staining on the outside face of the bearing housing
• Bearing temperature elevated more than 15 °C above ambient baseline during operation
• Increased bearing noise or measurable shaft run-out detected during operation
• Grease sample extraction showing cement contamination or discolouration