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At Hone-All, we offer a trepanning service as an alternative to deep hole boring for creating large diameter holes. For some applications and specific materials, trepanning is more efficient and cost-effective than deep hole boring, using less power than other drilling techniques.

Trepanning is widely used by clients in the aerospace, oil and gas and other manufacturing sectors.

Trepanning vs Deep Hole Boring: What’s The Difference?

The main difference between trepanning and deep hole boring is that trepanning cuts away only the outer edges at the perimeter of the hole, leaving a hollow centre and reclaims a solid core of material. Boring or drilling, on the other hand, drills away the entire diameter of the hole, converting it into chips, or swarf.

Thus, trepanning uses less energy when dealing with hardened metals, and also creates less waste material. Trepanning is also a faster operation than drilling and, as it uses indexable tooling, is excellent at processing multiple jobs in rapid succession and the remaining bar, or billet, can often be reused for a different purpose as long as you bear in mind that the properties of the material may have changed due to the work hardening effect sometimes created by trepanning.

Trepanning can create a hole through the material – for instance in hollow cylinders and pipes – or cut only partially into the surface, creating a so-called ‘blind hole’ or alternatively, create an external “sleeve” which may be removed or re-used.


Trepanning is used as a straightforward alternative to deep hole boring, as well as for several specialist applications:

  • Creating deep, end-to-end holes in cylinders and solid bar
  • Preparing metal components for further internal machining operations, such as counterboring or honing
  • Efficiently removing excess material from an outside diameter when a large flange is a feature of a relatively small part of the overall length

When To Use Trepanning

There are several circumstances in which trepanning is a more efficient or practical alternative to deep hole boring. These include:

  • Larger bore diameters 75mm +
  • When a standard drill head is unavailable or not cost-effective
  • When you require waste material in the form of a solid core – e.g. to increase scrap value when recycling or by request of the client
  • When you there is not a need for high levels of accuracy – trepanning tolerances are greater than standard boring or drilling tolerances
  • When working with hard metals

Compatible Metals

Trepanning can be used with a wide range of metals, including:

  • Aluminium
  • Stainless steel
  • Chrome
  • Nickel and nickel alloys
  • Titanium
  • Superalloys, including MP35N, Duplex etc

Find Out More

At Hone-All we use trepanning as one of several drilling and boring methods, to deliver high-performance parts to client specifications. To find out more, please call 01525 370666 today.


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