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Deep hole machining - Deep hole cutting solutions

Gundrilling machines - Deep hole drilling machines - BTA drilling machines - BTA boring Machines - SRB Machines - High speed deep hole drilling machines - Micro drilling machine - Mold drilling machine - Table type drilling machine

Profimach® Specialist in Deep Holes Machines

High quality affordable deep hole drilling- and boring machines

Our high precision deep hole drilling machines, BTA and gundrilling machines have been specially developed and improved in recent years. 

All essential castings are made of high grade of cast iron that is stress relieved through annealing to eliminate internal stress. With the greatest stiffness and stability of the castings, our machines are suitable for precision deep hole working.

Our deep hole drilling machines, BTA drilling machines and gundrilling machines

are offered with full two-year limited warranty.

What is Deep Hole Drilling?

A deep hole is defined by its depth-to-diameter ratio (D:d),

and typically holes greater than 10:1 are considered deep holes.

Deep hole machining means machining of holes deeper than ten times the hole diameter. This can be done in different machine set-ups.  The most common method is rotating the work piece while the tool is fed in a linear movement. Rotating tool is another option as well as a combination of the two.

Deep hole machining is generally performed on dedicated deep hole drilling/boring machines which are manufactured and assembled to optimize the processes for straightness and efficiency. Advances in technology allow our highly capable BTA and gundrilling machines, produced under OEM, with applications exceeding depth-to-diameter ratio of 400:1.  

Deep hole drilling consists of BTA drilling (boring) and gun drilling, with additional processes designed for specific tolerance objectives and generally performed on BTA-style deep hole drilling machines. Deep hole machining is used in a variety of materials from aluminum to super-alloys, and is capable of achieving tight diameter control, straightness, and superior surface finish into workpieces. Deep hole drilling processes work by using special tools and setups to deliver high pressure coolant, evacuate chips cleanly, and achieve depth-to-diameter holes into metal beyond what a common CNC machine can reach. This allows manufacturers to achieve their manufacturing tolerances and production requirements reliably, accurately, and efficiently.

Regardless of method, the basic principles of drilling still apply, and the correct choice of cutting speeds and feeds are crucial. Satisfactory chip breaking, and removing the chips from the cutting edge without damaging the tool or work piece, is essential. One of the most important success factors is an effective coolant system.

Deep hole drilling: gundrilling and BTA-drilling

There are three traditional deep drilling methods: gundrills or single lip drill system, BTA or single tube system (STS) and ejector Sytem or double tube system (DTS).

Gun Drilling

Single Lip Drill System


Ø 2~40 mm 

BTA Drilling

Single Tube System


Ø 20~1400 mm 

Ejector Drilling

 Double Tube System


Ø 20~500 mm 

Gun drilling

Gun drilling is the oldest and most widely used method of deep hole drilling employed by industry today.  The drill or “gun drill” is generally a one-piece assembly consisting of a hollow cylindrical drill driver. Also, it is brazed to a V-shaped crimped tube and finally assembled to a brazed-on solid carbide drill head.  Both the crimped drill shank and the brazed-on carbide drill head from a kidney-shaped cross-section. Whereby the open V-shaped section acts as a chip flute.

Gun Drilling Systems Features

In all cases, gun drills require filtered, the high-pressure coolant that is introduced through the center of the crimped gun drill shank. Then the drill is directed to a coolant orifice in the carbide drill head.  The high-pressure coolant provides lubrication for the drill head. Also, this assures that all of the chips produced by the drill head are exhausted through the V-shaped chip flute of the gun drill shank.  Gun drilling is better known as an internal coolant supply / external chip exhaust method of drilling.

Gun drills are generally used on single purpose gun drilling machines as well as on a variety of machining. They have turning centers that are equipped with sufficient high-pressure coolant and filtrations systems.  With this system of drilling, one can expect to drill to depths in excess of 100 x dia.

BTA: Single Tube Systems - STS

The single tube system STS or sometimes referred to as the “BTA” system of drilling, is the reverse of a gun drilling system.  Unlike the gun drill, the STS or “BTA” drilling system assembly consists of a drill head that is attached to a ground cylindrical tube. This is by either an internal or external fast lead thread.  The drill tube or boring bar is smaller in diameter than the drill head which forms an annular space between the hole being drilled and the OD of the drill tube or boring bar.  This space is known as “oil room” and in conjunction with a coolant induction unit or a pressure head. In addition, it makes it possible to direct filtered high volume coolant to the drill head cutting edge.

Single Tube Systems Features

This pressure head seals against the entry side of the part to be drilled. Also, this directs the coolant to the detachable drill head.  The coolant provides lubrication for the drill head and assures that all of the chips produced by the drill head are directed through the detachable cutting head are flushed internally through the ID of a cylindrical hollow drill tube or boring bar.  This is better known as an external coolant supply / internal (ID) chip exhaust method of drilling.

The STS / BTA system supports tools ranging from 12 mm – 850mm diameter. These tools and this system allow depth to diameter ratios in excess of 100 x’s dia. In most cases, the STS / BTA system is set up on dedicated deep hole drilling machines. This system is the best choice for extremely deep bores. And, for materials with poor chip forming properties such as stainless steel, Titanium, and low carbon steel.

Double Tube System - DTS

The double tube system, DTS, also referred to as the Ejector system, is characterized by two tube construction. It consists of an outer and inner tube connected to a coolant inducer at one end and a drill head at the other by a four-start thread.

How does it work?

The pressurized coolant is introduced by the coolant connector to flow through the annular space between the two tubes, the inner and outer, towards the drill head. Most of the coolant flows through holes in the drill head therefore providing lubrication and chip evacuation within the inner tube of the system. Also, the remaining coolant is directed through the rear of the inner tube. This creates a partial vacuum in the inner tube that sucks the coolant and the chips from the drill head through the inner tube before transferring it to a chip exhaust port that is an interracial part of the coolant connector.

Double Tube Systems Requirements

Double Tube Systems do not require a sealing system and pressure head, unlike the less powerful Single Tube System. The DTS system can be used on conventional machine tools such as lathes, horizontal boring mills and machining centers which have suitable feed mechanisms, rigidity, and our self-contained coolant system. The DTS has more applications than it’s single tube counterpart.

Deep hole High speed Vertical Gun-Drilling Machines overview

High speed Vertical Deep hole gun drilling machines for mass production

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