deep hole drilling drilling tools gun drills

Gun drills (through coolant drill) are straight fluted drills which allow cutting fluid (either compressed air or a suitable liquid) to be injected through the drill's hollow body to the cutting face. They are used for deep hole drilling—a depth-to-diameter ratio of 300:1 or more is possible. Gun barrels are the obvious example; hence the name. Other uses include mold making, die making, and the manufacture of combustion engine parts such as crankcase, cylinder head, and woodwind musical instruments, such as uilleann pipes, as gun drills can drill long straight holes in metal, wood, and some plastics. The coolant provides lubrication and cooling to the cutting edges and removes the swarf or chips from the hole. Modern gun drills use carbide tips to prolong life and reduce total cost when compared with steel tips. Speed of drilling depends on the material being drilled, rotational speed, and the drill diameter; a high speed drill can cut a hole in P20 steel at 30 inches per minute.

Gun drilling can be done on several kinds of machine tools. On lathes, it is generally practical with hole depths of less than 50 diameters. There are also purpose-built gun drilling machines, where longer aspect ratios can be drilled.

There are three basic types of deep hole drilling.[2] Processes are categorized by how the cutting coolant flushes heat and chips from the cutting face. The three types of deep drilling are:

Gun drilling - The cutting tool is a fluted solid rod that has a hole bored down the center. Coolant is pumped through a hole in the inside of the drill. It flows back outside the drill, through the flute, bringing the chips with it.

BTA / STS (Boring and Trepanning Association / Single Tube System) - The cutting tool is a tube. Coolant is pumped in around the outside of the cutting tool and carries chips out through the center tube. For the tube to be strong enough and have an inner diameter large enough to carry chips away, the hole must be more than 5⁄8 inch (16 mm) in diameter.

 Ejector system - The cutting tool is a tube with another tube nested inside. Coolant flows through the smaller tube to the cutting face and then coolant and chips flow back through the larger tube. This is only an acceptable technology for holes of over 3⁄4 inch (19 mm) in diameter.

PR40(H10F)：

super micro-grain diamond tungsten steel, extensively applied, it can be applied in medium speed cutting and finish cutting of various materials with HRC≦28°. It has excellent impact resistance and general wear resistance, and has extensive application. Generally, it is applied for thicker cutting, discontinuous cutting and bad part fixture. After being coated, it has better result, can machine various materials of HRC50°. Comparing with ISOK20&general tungsten steel, it has 1-2 times lifetime and excellent wear resistance