The Art of Deep Hole Boring
ABOUT Gun Drilling & BTA Borers
In the production of precision bores, the conventional method of using fluting twist drills to process hole drilling is the established preferred method. However such methods have a limitation when drilling holes with depth of more than 10 times the diameter of drilling hole where problems like long cycle time, poor bore straightness and rough surface quality affect the part quality. Twist tool drilling also creates retraction and ejection of fillings, due to the long depth of the bore. Therefore deep hole drilling techniques was developed as a solution to an age old military problem of gun barrel drilling.
Currently, deep hole processing machines includes gun drill, BTA (Boring and tre-panning Association) and Eject Drilling, the selection depends on the bore diameter size. For deep hole boring, there are no retraction and ejection of filling during the deep hole drilling processing which is a special feature of gun drilling machines. For deep hole drilling with higher precision and higher speeds, gun drill machines are suitable for diameters below 30mm while drilling diameters over 30mm BTA or eject drilling is required.
Gun Drill tools
The structure of Gun Drilling tools consist of a cutting edge divided into single cutting edge and twin cutting edge. There is a V-shaped slot in between the cutting edge and the body’s outer diameter used for removing chips inside the body. The coolant penetrates through the whole length of the cutting tool, entering from the rear of the handle to the drill cutting edge, both acting as a lubricant and high pressured flushing to force out the cutting chips.
This previous method of cutting tool retraction and chip ejection cycle is not required during deep hole drilling. Using a Tungsten carbide gun drill tools, it is possible to achieve good surface quality with H7-H9 accuracies with an experienced operator!
About Microdrilling Machinery
Microdrilling is a “made to order” manufacturer of BTA Deep Hole borers and Gun drill machines with a customer centric focus of application solutions through quality machinery, rather than “off the rack” machines. Highly knowledgeable and specialized in deep hole boring with sales & service support from Flexmech, they are reliable in machine quality and solutions application in the Aerospace, Automotive & Oil&Gas industries.
The machines are categorized to small gun drills from Ø2 – 12.00mm up to a depth of 1,000mm, up to the BTA Deep Hole Borers for bores up to Ø50mm to a depth of 6,000mm! For more information on these machines, click here.