What is gun drilling?
Gun drilling is a process that produces deep, straight holes in a variety of materials. A gundrill tool differs from a conventional twist drill by its unique head geometry; a standard gundrill has a single effective cutting edge. Guide pads burnish the hole while drilling, allowing the hole to maintain straightness. The result of this burnishing activity is a very round hole with a precision diameter.
Gun drilling was initially developed for manufacturing rifle barrels. Armament manufacturing continues to be a common use of this process. Other common industries include energy, oil and gas exploration, engines, diesel fuel components, and plastic injection molds.
Holes deeper than 20:1 generally require a dedicated gundrilling machine to achieve highest productivity and process reliability.
Gun drilling differs from BTA drilling due to the coolant entry and chip removal. Gundrills introduce coolant through a small hole within the tool, and chip removal occurs through a groove outside the tool. BTA drilling has fluid enter through a mechanism around the tool, while chips are evacuated through the drill itself. BTA drilling becomes more effective than gundrilling around a 50mm hole diameter.
Optimal Specifications for Gun Drilling Process
Gun drilling is the appropriate method for a range of drilling diameters and depths. Extremely deep holes and small diameter holes utilize gundrilling with specific equipment to maintain straightness and precision. Larger holes may be achieved more effectively with BTA drilling methods.
Gun Drilling Diameters
|1-3mm||Possible with proper equipment|
|3mm – 25mm||Common|
|50-75mm||Possible, but less productive than BTA drilling|
Gun Drilling Depths
|5:1||Common twist drills|
|10:1||High performance twist drills with through-tool coolant|
|20:1||Special deep hole drilling tools with through-tool coolant|
|100:1||Gun drilling tools on dedicated gun drilling machine|
|200:1||Gun drilling tools on high performance gun drilling machines|
|400:1||Extreme drilling range, proprietary processes and equipment required|