Precision Twist R89CO Cobalt Steel Jobber Drill Bit, Gold Oxide Finish, Round Shank, Spiral Flute, 135 Degree Split Point, #43 (Pack of 12)
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The Precision Twist R89CO jobber-length drill bit is a 135-degree split-point, heavy-duty, round shank drill bit made of high speed steel (HSS) and cobalt with a gold oxide finish. They meet NAS 907 Type D, aircraft industry specifications for heat resistance and use for drilling hard, tough materials. Best performance with drilling into hardened, tempered alloy steel, nodular graphite malleable cast iron, titanium, and alloyed nickel. It is suitable for drilling to a depth up to four times the diameter of the drill. The shank diameter is the same as the drill size.
While the R89CO series was designed for aircraft industry, they also work well for drilling into a variety of materials. The 135-degree split-point drill geometry ensure an accurate hole by reducing walking when the hole is started. The finish retains lubricants to aid in wear resistance and chip flow.
The R89CO series has a type N flute form (a regular helix angle of 21 to 34 degrees). The gold oxide is a low temperature heat treatment which reduces grinding stress within the tool, and has an appealing, easy-to-identify gold color. Gold oxide is commonly used to identify cobalt steel tools. 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.
Made of HSS with cobalt, many times harder/stiffer than HSS, will hold an edge longer, and will 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) and NAS 907 type D industry standards, which ensure that drill bits around the world conform 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 are commonly used to drill holes with hand-operated drills, standalone drill presses, or lathes. The flutes of the drill bit act a passageway for chip extraction from the hole and for coolant to enter the hole. These drill bits have a right-hand twist that brings chips up and away from the cutting edge.
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.
- Precision Twist
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