3 Methods of Drilling Deep Holes

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Deep hole drilling is nothing new. The technology has been used for a long time in the oil and gas industry. Here, we define the idea of a “deep hole” and thereafter discuss the three main ways of drilling the deep holes (a process also known as known as deep hole drilling). In general, any hole where the depth is more than four to five times the diameter is considered a deep hole. In some cases, the depth of the whole is usually up to 400 times the length of the diameter. As you can guess, drilling such a hole can be very difficult, particularly removing chips from the flutes of the drills. With a proper tooling and dedicated deep hole drilling machine, drilling such thin holes is no longer a problem. Depths up to 400:1 can be easily achieved.

There are three known ways of drilling such deep holes.
1. Gun drilling
Gun drilling is currently the most popular way of drilling deep holes. Getting its name from the fact that the technology was first used to drill gun barrels more than 100 years ago, gun drilling is an effective, efficient, and very reliable way of deep hole drilling. Today’s refined machinery and technology has made gun drilling the preferred method of drilling short as well as long holes in the oil and gas industry. The gun drill has a hollow tube with a “V” shaped groove positioned strategically along the length. It also features a carbide cutting tip designed in such a way that it guides the gun down the hole to ensure a very straight hole.

There are a few companies that manufacture gun drills and Botek is the market leader for precision deep hole drilling tools, gun drills and Carbide twist drills with more than 30 years of experience in designing and manufacturing tools for all deep hole drilling applications. Botek recently launch a high performance inserted gun drill which is ideally suited on CNC machines with a coolant system. The German company has market presence in Singapore, Malaysia, Indonesia, Thailand etc.

2. BTA/STS drilling
BTA or STS drills are single tube system drills. It is a more recent process compared to the gun drilling technology. The main difference between a gun drill and the BTA/STS is that while in gun drills the coolant is introduced into the center of the drill through the spindle of the gun itself, in BTA/STS drills the same coolant is introduced around the drill tube at the pressure head. Gun drills evacuate chips along the “V” groove whereas BTA/STS drills evacuate similar chips through the center of the drill.

3. Ejector drilling
Lastly, ejector or tube system drilling are similar to BTA drilling except that in Ejector drills, the drill tube consists of two tubes; an inner tube and an outer tube. The coolant is introduced at the spindle via a simple rotating connector, passing between the inner and outer tube. Chips are evacuated through the inner tube.