D/AA Series Drill America 5/16 x 6 High Speed Steel Aircraft Extension Drill Bit Pack of 12

Drill America 5/16' x 6' High Speed Steel Aircraft Extension Drill Bit (Pack of 12), D/AA Series: Home Improvement. Drill America 5/16" x 6" High Speed Steel Aircraft Extension Drill Bit (Pack of 12), D/AA Series: Home Improvement. High-speed steel tools are good for most general purpose applications, offering a combination of hardness and toughness for wear resistance 。 Black oxide treatment adds lubricity and creates small pockets on the surface of the tool that act to hold coolant near the cutting edge 。 Round shanks allow use with a wide variety of toolholding systems 。 When run in a counterclockwise direction (right-hand cut) spiral fluted tools evacuate chips up and out of the cut to reduce clogging 。 Manufactured to National Aerospace Standard 907 。 Drill America D/AA/C series High-Speed Steel premium quality drill bit is manufactured to National Aerospace Standard 907. 1 degrees split point is self-centering and reduces thrust. Ideal for drilling in mild steels where extra length for reach is required. They have a black oxide surface treatment that is abrasion resistant, reduces chip welding and improves chip flow. 。。。