.高螺旋角度40°，使用於抗拉強度低的、軟的， 且切屑長的及易黏附於刀口之被削材。 .適用於鋁、鋁合金、鋅、精鍊銅等被切削材。 .40° helix angle makes the drills ideal for drilling workpieces with low tensile strength, soft, long chips and easy to adhere on cutting edges. .Suitable for drilling Aluminum