The Kong Zhuan inside the small diameter that company of estate of Japanese special contented develops is two kinds with cutting tool cent, one kind is NTK file, can machine inside aperture diameter is φ 10mm of 5 ～ φ , effective treatment length is 45mm the following; Another kind is the NTK lathe tool that machines dinky diameter, the diameter of the aperture inside treatment is φ 3mm of 1 ～ φ , effective treatment length is 8mm the following. The file is but dislocation type construction, knife pommel ministry has bit chamfer, bit places firm with locking bolt, bit assembles and unassemble all very convenient; Lathe tool places firm style construction for machinery, bit originallies by snail clench. The bit material of NTK file has cermet and coat of imperceptible grain hard alloy two kinds, measurement standards is much, can satisfy all sorts of inside the need that aperture appearance machines; The bit material of NTK lathe tool is VMI of special hard alloy. CNC MillingCNC Machining