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What is deep hole drilling ?

Deep hole drilling is where the hole depth to diameter can be upto 400:1 ratio. Deep hole drilling consists of two techniques: Gun Drilling & BTA Drilling.
Gun Drilling
Gundrilling is a deep hole drilling process that uses a long cutting tool to produce holes in metal at large depth-to-diameter ratios. Gun drilling is effective in diameters from 1 – 50 mm [0.04 – 2.00 in]. A gundrill tool differs from a conventional twist drill by its unique shank and head geometry; a standard gundrill has a V shape groove to flash our chips and oil with built in coolant hole in the tool.

The gundrilling process is able to drill deep holes beyond what is possible with conventional machinery and tooling such as twist drills, by using high pressure coolant for clean chip exhaust, even at extreme depths.
Gun drilling was initially developed for the manufacture of gun barrels, where both straightness and barrel durability were essential to properly functioning barrels.
Gradually the gun drilling technology is adopted by any industry which require long straight holes and difficult to achieve with twist drill. The industries include mold and die making, auto parts, fuel common rail, engine valve, pellet die, cannulated medical drill, cam shaft, crank shaft, ….. for any industry as applications need a long straight hole.
BAT Drilling
BTA stands for Boring and Trepanning Association, and is also sometimes referred to as STS (single tube system) drilling, as it uses one single drill tube for the BTA tool, compared to other processes such as ejector drilling, which use two.
BTA drilling is a deep hole drilling method which was created by the Boring and Trepanning Association in the 1940's.

BTA drilling is a deep hole drilling process that uses a specialized drilling tool on a long drill tube to produce deep holes in metal, from holes with a diameter of 20 mm [0.80 in] and larger, up to depth-to-diameter ratios of 400:1. BTA drilling is the most effective method of drilling deep holes, as it is a cleaner, more reliable and capable process than conventional twist drills, and can achieve larger diameters and higher feed rates than the alternative gundrilling.
BTA drilling tool heads are threaded or mounted onto long drill tubes, and use multiple cutting insert on a single tool to remove chips efficiently, flushing them out with high-pressure coolant through holes in the tool head, then out the drill tube and through the machining spindle. BTA tooling is available in brazed or inserted carbide configurations.

HTT has being dedicated in deep hole drilling for over 25 years. We offer a full line of deep hole drilling machines with tailored made specifical fixturing and machine configurations to meet customer applications and requirements.

You can contact us for information about our deep hole drilling machines.


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