Deep hole drilling (DHD) – or deep hole machining (DHM) – is a residual stress measurement technique often referred to as gun drilling. It’s a prominent method in engineering materials and components used across numerous sectors, including automotive and vehicle construction, aerospace and renewable energy. Deep hole drilling is also used in die and mould making and hydraulics or pneumatic components.

Today, there’s a growing demand to put gun drilling into a multi-tasking format, just as you would with common machining techniques such as milling, turning and gear-cutting on one platform. With deep hole machining being a multi-task platform you can create opportunities to offer an incredibly high-quality finished product.

How Does Deep Hole Drilling Work?

Deep hole machining is used when a project requires high-precision round bores. It can produce holes that are within extremely tight tolerances, providing incredible accuracy compared to conventional drilling methods.

These machines use special tools and setups to deliver high-pressure coolant, cleanly evacuate chips while achieving depth-to-diameter holes beyond the capabilities of a typical CNC machine. This means manufacturers can reliably, accurately and efficiently achieve tolerances and production requirements..

It is a highly-specialised machining operation that only a select few engineering companies can perform, and PRV is one of them.

Deep Hole Drilling At PRV Engineering

PRV Engineering is one of a few skilled engineering companies in the UK with a deep hole machining facility. Using our 10 deep hole drilling machines and other cutting-edge equipment, we have developed a full range of supporting processes. PRV Engineering can offer deep hole drilling as a stand-alone service or as part of a complete manufacturing package.

To ensure the tightest of tolerances throughout the entire gun drilling process, PRV also invested in state-of-the-art calibration equipment. With some of the best kit on the market, we can drill centres of up to 2200mm on non-cylindrical components and 6000mm on cylindrical components. Our facility can provide component processes to whichever stage you require.

Deep Hole Drilling Applications

Considering the scope of this advanced machining method, only a select few engineering companies can provide the required service. Deep hole drilling is used on a variety of materials from basic aluminium to super-alloys. Here’s a brief breakdown of the main industries and applications for deep hole drilling.

Oil and Gas Sector

Deep hole drilling machines are used for drill collars, drill pipes and submersible pumps, among others. It achieves high-precision drilling with minimal runout in alloys such as nickel steels. It also comes with additional features which have been developed specifically for a task, i.e. monitoring chip breakage for more reliable cutting.

Automotive Engineering And Construction


The automotive sector is probably one of the biggest when it comes to gun drilling applications as it involves numerous components. This includes:

  • camshafts and crankshafts
  • transmission shafts
  • driveshafts
  • flanged shafts
  • injection nozzle bodies
  • fuel rails
  • valves
  • con-rods or piston pins

The automotive sector relies heavily on deep hole drilling machines as they can handle large quantities and maximum output in the shortest possible time. When a project requires through-holes in camshafts and common rails, for example, automakers can drill simultaneously from two sides. Some designs can incorporate up to 12 spindles which allows much faster cycle times.

Aerospace Engineering

In aerospace engineering, gun drilling is used to produce components such as landing gear, turbine shafts and refuelling pipes. These are often made of titanium, tempered steels or special alloys, like Inconel, which require extreme precision. The material-saving construction process is common in aircraft production which often requires contours with different hole diameters. Some deep hole drilling machines can produce all the desired internal contours through a process known as bottle boring.

Ship Construction

Shipbuilding is another sector that involves several components that require absolute precision. Deep hole machining machines can ensure accuracy, reliability and efficiency when it comes to manufacturing rotor shafts but also in making components for pumps and powertrains.

Deep Hole Drilling For Medical Technology

The medical sector has seen some incredible developments in recent years thanks to advances in technology and processes. Deep hole machining, in particular, has enabled (and improved) the production of several components. This includes medical implants such as bone nails, medullary nails, bone screws and stents.

Most of these components are made from titanium or stainless steel alloys which require absolute maximum precision with minimum runout. Parts with extremely thin walls pose a real problem for medical equipment manufacturers but gun drilling can reliably and effectively help overcome these challenges.

Hydraulic or Pneumatic Components

Deep hole machining is also a prominent feature in earth-moving machines such as rubbish trucks, dredgers and even forklifts. These machines have hydraulic and pneumatic cylinder tubes which must always be functional for long periods and under extreme conditions. For that reason, precision engineering is essential to achieve dimensional accuracy and high surface quality on the cylinder tubes.


Renewable Energy Sector

The energy sector is one of the most technologically advanced industries with a significant number of developments in recent years. When it comes to windmill shafts, turbine shafts or rotors for wind-power systems, gun drilling is the best solution. Component dimensions are tight which means they require customised, high-precision machining, something other methods simply cannot live up to.

Related: ‘Tools And Technologies Of Deep Hole Machining

Why Choose PRV Engineering

As one of Europe’s top suppliers of precision engineering services, we continue to invest heavily in acquiring and training highly skilled staff and state-of-the-art machinery. Some of the sectors we work with include aerospace, defence, automotive, construction, rail, oil and gas.

We can manufacture from own designs, specific drawings and specifications or OEM samples depending on your requirements. And, if requested, we can also provide you with complete drawings and stress analysis calculations.

Working with basic mild steels to the more exotic Monel, Inconel, Hastelloy and Titanium, we cater for one-offs, large batch production and Rapid Prototyping. If you have any questions about deep hole drilling, please leave us a comment below or contact us via the website. You can also find us on TwitterFacebookYouTube or LinkedIn.

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