The Precision Twist D444 jobber-length, carbide-tipped, round shank drill bit performs best when drilling holes into cast iron. It can drill to a depth up to four times the diameter of the drill size. The shank diameter is the same as the drill size.
The D444 series has a type N flute form, with a regular helix (21 to 34 degrees) angle. Uncoated (bright) tools have no finish or coating. They are a common choice for general use applications. The round shank with tang provides a means to securely hold the drill bit in the tool holder. Spiral flutes act as a passageway for chip extraction from the hole and for coolant to enter the hole. Right-hand twist brings chips up and away from the cutting edge.
It is tipped with carbide (a metallic carbide composite with binder material), which is much harder and stiffer than high-speed steel (HSS), and will hold an edge longer, and deflect less than HSS. These are also more resistant to heat than HSS. These qualities allow it to run at higher speeds and feeds. They are made to ANSI (fractional sizing) industry standards, which help ensure that drill bits around the world confirm to the same specifications.
Drilling, or hole making, is the most common metalworking operation in the world. Twist drill bits are the most common type of drill bit used. Twist drill bits can be used in hand-operated drills, standalone drill presses, or a lathe.
Precision manufactures machine tools under the following brands: Precision Twist, Precision Dormer, and Union Butterfield. They have locations around the world, and provide tools adhering to ANSI, NAS, and DIN standards.