Deep hole drilling is a specialised drilling process which is used to create holes that are much deeper than normal drilling can handle.
A hole is considered a “deep hole” when its depth is more than 10 times its diameter. For example, if the hole is 10 mm wide and the depth is 100 mm or more, it comes under deep hole drilling.
Deep hole drilling process is mainly used when industries need holes that are straight, accurate, and should have smooth finish inside, when it comes to regular drilling, it will not be able to work on deep holes to tool bending, poor chip removal, and overheating.
Deep hole drilling is used in range of industries such as oil and gas, aerospace, automotive, mould and die making, and defence manufacturing.
Methods Used for Deep Hole Drilling
Deep hole drilling is not done using ordinary drills. Instead, specific methods and tools are used to ensure the hole stays straight, the tool remains cool, and chips are removed continuously. Here are the most commonly used deep hole drilling methods.
Gun Drilling Method
Gun drilling is one of the most used deep hole drilling methods, especially for small and medium diameter holes.
When it comes to this method it uses a long, specially designed drill tool that can drill deep while maintaining good straightness.
One of the major advantages of gun drilling is the use of high-pressure coolant, which is pushed through the tool to cool the cutting area and carry chips out of the hole.
Gun drilling is commonly used in precision parts where accuracy and surface finish are important, such as mould components, aerospace parts, automotive components, and high-precision engineering applications.
BTA Drilling Method (Boring and Trepanning Association)
BTA drilling is a deep hole drilling method mainly used for larger diameter holes. This method is preferred when the hole size is bigger and the material removal needs to be faster and more efficient.
In BTA drilling, coolant is supplied in a way that supports stable drilling, and chips are removed effectively through the tool system.
BTA drilling method is mostly used in heavy duty manufacturing because it is more suitable for large parts and high production requirements.
This method is mostly used in the Industries such as oil and gas, heavy engineering, and large machinery production commonly use BTA drilling for deep holes with larger diameters.
Ejector Drilling Method
Ejector drilling is another very commonly used method used for deep hole drilling and it is mostly used when manufacturers want a deep hole drilling solution that can work with more standard machine setups.
This method also uses coolant pressure to remove chips from deep inside the hole. The ejector system helps push the chips out efficiently.
Ejector drilling is commonly used for medium and large deep holes where stable drilling, good chip control, and consistent results are required, especially in industrial component manufacturing.
Pull Boring Method
Pull boring is a deep hole machining method used when the hole needs to be improved after the initial drilling process.
When it comes to pull boring method, a boring tool is pulled through the hole instead of being pushed in like a drill. This pulling action helps keep the tool stable and improves accuracy.
Pull boring is very helpful, and mostly used when the manufacturer wants a better internal finish, better straightness, and a more accurate hole diameter.
Counterboring Method
Counterboring is a method used when a deep hole needs a wider opening at the top portion of the hole. Counterboring is mostly used when a bolt head, screw head, or fitting needs to sit properly inside the hole at the same level of the whole, without sticking out.
In deep hole drilling applications, counterboring is done using specialised tools to ensure the enlarged portion stays aligned with the main hole.
