Underground mining sites depend on development drilling precision, so every component matters. This case study explores how A1 Metallising’s engineering brought a worn Sandvik Jumbo rollover back to service-ready condition.
Underground drilling for mining operations
What is a Rollover?
A rollover is a rotary actuator that converts hydraulic energy to rotary motion. This motion allows the drill feed system to roll over, greatly reducing the limitations in drilling angles. In mining equipment, rotary actuators are used extensively on drill rigs to allow components such as feed rails and masts to be positioned to exact angles with the slightest of ease.
What Causes a Rotary to Fail Prematurely?
Rock dust and debris contaminate hydraulic systems, while constant vibration and high operating pressures stress sealing surfaces. Extreme temperature fluctuations cause expansion and contraction cycles that gradually wear surfaces. The demanding 24/7 duty cycles of mining work also accelerate normal wear patterns; this failure allows oil to leak externally and reduces hydraulic efficiency, which limits overall machine performance.
Condition of the rollover actuator when received
The Challenge
This Sandvik Jumbo drilling rig faced a significant challenge when its rollover actuator began showing performance degradation.
The seal journals (these are precision-machined low stiction surface where hydraulic seals maintain a seal between the hydraulic circuit and outside the environment) had developed wear patterns that compromised sealing effectiveness and rollover power due to external oil leaks.
Without proper feed rail positioning ability, the rig could no longer execute the full range of required drilling tasks—bottom hole lifters, side paradox holes, meshing, and bolting operations which are essential for underground development work, effectively stopping all drilling operations.
Why This Wasn’t a Standard Restoration
This restoration poses several demanding requirements:
- Zero room for error – Any performance compromise would halt production
- Precision sealing demands – Seal journals require extremely precise dimensional requirements for proper hydraulic seal contact
- Harsh operating environment – The coating needed to withstand extreme underground conditions, vibration, and contamination
- Time pressure – Every day of equipment unavailability directly impacted mining productivity and costs
A1 Metallising’s Approach to Surface Recovery
A1 Metallising Services approached this restoration using our Electric Twin Arc Spray System with our superior 420 stainless steel coating.
This thermal spray process rebuilt the worn seal surfaces with exceptional precision while providing controlled temperature.
The process was selected for its cost effectiveness, speed of application and very low heat input. Unlike laser cladding and other welding processes which can introduce excessive heat to the component, Electric Twin Arc Spray builds up surfaces quickly, allowing precise control over final dimensions while avoiding any thermal distortion.
The Results
The restoration successfully returned the rollover actuator to full capacity. The enhanced 420 stainless steel surfaces provide superior wear resistance compared to original manufacturing, extending the service life of the component without compromising how well the seals perform.
Key Outcomes:
- Restored full production drilling performance
- Eliminated seal leakage issues completely and ensured a more robust surface for longer service intervals
- Achieved estimated cost savings of 75-80% versus new component
- Extended component service life significantly
- Fast restoration without extended delays
A1’s Proven Capabilities
This project demonstrates several key strengths that A1 Metallising Services bring to the table:
- Premium OEM expertise – Proven ability to restore components from leading manufacturers like Sandvik and Epiroc to original design standards
- Economic solutions – Substantial savings compared to new component replacement
- Precision engineering – 60+ years of surface engineering excellence ensures demanding applications meet exact specifications
- Minimal disruption – Fast turnaround solutions that keep drilling equipment running and productive
The Wider Value
The mining facility got their drilling rig back in working order without the weeks-long wait for a new part. More importantly, the restored actuator now performs for longer, thanks to the superior properties of the 420 stainless steel coating.
For the mining development team, this meant keeping their development target on track while saving thousands of dollars today and into the future.
Through precision surface engineering, A1 Metallising Services ensured continued productivity in demanding underground mining applications, proving that restoration can deliver better-than-new performance while keeping production on track.
