HARDLOCK

Published: April 2022
Category: HARDLOCK® Nut / TBM / Industrial Fastening

Why Self-Locking Nuts Matter in Tunnel Boring Machines (TBM)

A tunnel boring machine (TBM), often referred to as a “mole,” is a highly advanced piece of equipment used to excavate tunnels through a wide range of geological conditions—from soft soil to extremely hard rock. Tunnel diameters can vary from as small as 1 meter (micro-TBMs) up to nearly 16 meters.

In such demanding environments, mechanical reliability and fastening safety are critical. One of the most common and costly issues in TBM operations is loosening of bolted joints, particularly in bit housing assemblies.

The Problem: Loosening and Downtime

TBMs are exposed to extreme vibrations, impacts, and cyclic loads, which can lead to:

  • Loss of preload in bolted joints
  • Damage to bit housing assemblies
  • Increased maintenance frequency
  • Costly delays in tunnel excavation

Even a minor failure in fastening systems can significantly extend project timelines and increase operational costs.

The Solution: HARDLOCK® Self-Locking Nut

To eliminate these risks, leading TBM manufacturers have adopted the HARDLOCK® nut, a proven self-locking fastening solution designed for high-vibration environments.

Companies using HARDLOCK® nuts in TBM applications include:

  • JIM Technology Corporation
  • EM Korea Co., Ltd.
  • Kawasaki Heavy Industries
  • Hitachi Zosen Corporation
  • IHI Corporation
  • Robbins Company

How HARDLOCK® Technology Works

Unlike conventional nuts, HARDLOCK® nuts:

  • Eliminate clearance between threads, preventing micro-movements
  • Maintain consistent clamp force under vibration and impact
  • Provide a fail-safe mechanical locking mechanism
  • Are fully metallic, ensuring long-term durability without degradation

This unique design ensures that bolted joints remain secure even in the harshest TBM operating conditions.

Key Advantages of HARDLOCK® Nuts

  • ✅ Extreme vibration resistance – no loosening under dynamic loads
  • ✅ Reusable without performance loss
  • ✅ Precise torque control for reliable preload
  • ✅ Wide material compatibility (steel, stainless steel, titanium, etc.)
  • ✅ No special tools required for installation

Proven Performance in Heavy Industry

HARDLOCK® nuts have demonstrated exceptional reliability across multiple industries where safety is critical, including:

  • Tunnel boring machines (TBM)
  • Railway infrastructure
  • Energy and power systems
  • Heavy industrial machinery

Their ability to maintain joint integrity directly translates into reduced downtime, improved safety, and lower maintenance costs.

Conclusion: Safety Is Power

In TBM operations, where failure is not an option, choosing the right fastening solution is essential. HARDLOCK® nuts provide unmatched self-locking performance, ensuring that critical components remain secure under the most extreme conditions.

👉 If you need a detailed and up-to-date presentation, contact us at: info@aymara.cz