Epiroc ET55 drill string: design, wear and energy-transfer notes for mine engineers
Reviewed by Joe Ashwell
First reported on International Mining – News
30 Second Briefing
Epiroc has launched the ET55 drill string, replacing the long‑running ST58 system and extending its ET next‑generation family with a fully shoulder‑drive connection from top hammer to bit. The ET55 applies the same design principles as earlier ET systems, using a shoulder drive interface along the entire string to improve energy transfer and reduce thread wear compared with conventional threaded couplings. For mine operators running top‑hammer production drilling, the unified shoulder drive geometry should simplify string configuration and potentially extend service life in abrasive ground.
Technical Brief
- Connection geometry is standardised across the string to reduce mixed-interface adaptor use underground.
- Shoulder-drive design is intended to maintain torque capacity even with moderate thread flank wear.
- Unified interface simplifies inventory: fewer coupling types and spare SKUs for production drilling operations.
- ET55 targets abrasive, high-penetration-rate benches where thread galling and wash-out drive current change-outs.
- System is engineered for high-energy modern rock drills, aiming to limit stress concentrations at joint transitions.
- Reduced thread engagement during make-up/break-out is expected to shorten rod change times at the rig.
Our Take
In our database, Epiroc’s recent activity skews heavily toward underground and large open-pit drilling systems (Pit Viper rigs, Automatic Bit Changer, Deep Automation), so a new drill string like the ET55 is likely aimed at tightening the integration between consumables and these higher-spec fleets.
The cluster of 2026 orders for Epiroc equipment at Sibanye-Stillwater’s Rustenburg platinum operations and MMG’s Khoemacau copper mine suggests that any performance gains or life improvements from the ET55 drill string could quickly scale across multiple tier-one customers rather than remaining a niche product.
With 2,393 tag-matched ‘Projects’ and ‘Product’ pieces in our coverage, Epiroc stands out as one of the more frequently recurring OEMs, signalling that incremental hardware upgrades such as the ET55 are being rolled out alongside automation and electrification rather than as standalone consumables changes.
Prepared by collating external sources, AI-assisted tools, and Geomechanics.io’s proprietary mining database, then reviewed for technical accuracy & edited by our geotechnical team.
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