Long and Extra Long Series Twist Drill

These drills are utilized in deep hole or long reach drilling applications in many  kinds of material for either hand held or fixed spindle use.

It has  Fractional,Wire,Letter and Metric Sizes.

Comply Standard ANSI B94.

Overall Length have two size 6" and 12".

In the mechanical manufacturing process, the hole depth is generally more than 10 times the diameter of the cylindrical hole is called a deep hole. Deep holes are distinguished by the size of the ratio (L/D) of the hole depth (L) to the hole diameter (D), and are usually categorized into three types: general deep holes, medium deep holes, and special deep holes. (Ps: The larger the ratio of L/D, the more difficult it is to process.)

Deep holes are categorized by L/D ratio:

(1) L/D = 10 to 20, belonging to the general deep hole. Often in the drill press or lathe with a long twist drill processing.

(2) L/D = 20 ~ 30, belongs to the medium deep hole. Often processed on lathe.

(3) L/D=30～100, belongs to special deep hole. It must be processed on deep hole drilling machine or special equipment using deep hole drilling.