In steel manufacturing, the sinter fan never stops. This massive industrial fan draws air through the sinter bed during heating, creating the suction needed for combustion and producing the feedstock that keeps blast furnaces running. The rotor shaft supports and rotates the fan blades continuously. When a 10-tonne shaft fails, steel production stops cold.
A Shaft Under Pressure
A steel manufacturer faced exactly this scenario with their sinter fan rotor shaft – a component measuring 1,380mm in diameter and 7,070mm in length. Years of continuous operation in harsh conditions had taken their toll.
The bearing journals – precisely machined surfaces supporting the shaft’s weight and loads – showed rust pitting up to 0.03mm deep. Even 0.1mm of wear at these contact points causes vibration, bearing failure, and catastrophic damage.
The seal journals (mechanical seals that prevent contaminants from entering bearing housings) had developed grooves 0.7mm to 0.9mm deep from exposure to abrasive iron ore dust.
The thrust faces, flat surfaces perpendicular to the shaft rotation that handle high-pressure axial loads, were similarly rusted and pitted.
The component needed restoration within 0.02mm tolerances across all critical surfaces. Adding urgency, the shaft had to meet a tight deadline for balancing operations in Melbourne. Each day of delay directly impacted steel production capacity, and sourcing a replacement would mean months of lead time and substantial costs.
Precision Under Controlled Heat
Rokit 401 nickel-chrome alloy is deposited using the powder laser to rebuild every compromised surface. The process suited this shaft’s size, providing controlled heat input that maintained dimensional accuracy and preserved the base material’s mechanical properties – critical for a component supporting rotating fan blades under continuous loads and vibration.
It rebuilt worn dimensions, eliminated rust damage, and filled pitted areas across critical surfaces. Rokit 401’s composition (18% chromium, 2.5% nickel) delivered hardness between 55-58 HRC while maintaining machinability for final finishing.
The clad surface is harder and more corrosion-resistant than the original, giving the shaft a longer service life in the same abrasive, high-dust environment.
Back Online, Built to Last
All critical surfaces were restored within the client’s specified dimensions. The shaft reached Melbourne for balancing, with no further delay to the production timeline.
A 10-tonne shaft with rust pitting across every critical surface, back in service with better durability than the original. That’s what 60 years of surface engineering experience and Australia’s first and only hot-wire laser facility makes possible.
