The arising radial chip cutting forces are transmitted via the supporting strips to the bore wall. This produces press-smoothing of the surface. This effect can be further intensified by the design of the supporting strips. The result is excellent surface quality.
Fig.: surface quality
Diameter tolerances up to IT 7 can be achieved with TBT single-lip drills.
The drill bush or pilot bore bearing against the tool, and the bore itself, give the single-lip drill exact guidance, so that the bore course remains within minimised tolerance limits.
Legend for Figure:
Horizontal axis: Drilling depth in mm
Vertical axis: Off-centre in mm
Upper graphic: Rotating tool
Lower graphic: Rotating workpiece