Efficiency, safety and smart investment in TBM operations

Longer Life of Cutter Tools

Why It Matters

Selecting the best tools for the cutterhead is one of the greatest challenges for any Tunnel Boring Machine (TBM) engineer. It’s not just about saving costs — it’s about minimizing operational risks, avoiding breakdowns, and ensuring continuous advance.

The Benefits of High-Performance Cutter Tools

  • LESS TOOL CONSUMPTION:
    Cutterhead tools are one of the most expensive consumables in a TBM operation. Improving their lifespan can drastically reduce the maintenance budget.

  • Fewer cutterhead maintenance stops:
    Every time tools are replaced, tunnel advance halts. Although other tasks (belt extensions, cable handling, etc.) are often scheduled during these stops, the limited workspace and small crews involved make it a time-consuming process.
  • Reduced risk of damage:
    Sudden changes in ground conditions are always a risk. Stronger tools give the TBM operator the reaction time needed to detect changes before damage is caused to the cutterhead.

Our Experience in Urban Tunneling

We addressed this challenge in a soft ground tunnel project for an urban rail line, located beneath densely populated streets. The contractor was highly concerned about tool wear, since the TBM could not be stopped at arbitrary locations due to potential surface settlements.

Key project parameters:

  • Earth pressure: ~2.5 bar

  • Maintenance required hyperbaric interventions by divers

  • Ventilation shafts and stations every 500 meters

  • Goal: Advance from shaft to shaft without intermediate stops

Our solution:

  • One-piece scrapers with four rows of tungsten carbide

  • Smaller tools equipped with two rows

  • Full hardfacing on ground-contact surfaces:

    • Embedded tungsten carbide particles

    • Surrounded by a tough metal matrix

This hardfacing layer protected the wear rows during transitions (like diaphragm walls), ensuring the tools wore gradually and safely. The result: successful advance without unplanned maintenance stops.

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