For over last 5 decades, various models for predicting the uncut chip geometry have been
introduced. The conventional ( cos )h f z model is, surprisingly, still well accepted and applied in
many sections despite of being derived from the circular tool trajectory instead of the trochoid one.
As a result, this paper presents an analysis of geometric distortion between the actual uncut chip and
the conventional model through both the in-cutting angles and the new approached dimensionless
parameters. In this works, the VBA for AutoCAD programming was implemented as the main tool for
creating uncut chips and determining their characteristics. The trochoid trajectory was generated from
a series of successive points on the synthetic curves. According to the comparative study’s results, the
proposed criteria for assessing the geometric distortion can identify the differentia between the actual
uncut chip and the conventional model as expected. It is then possible to draw a conclusion that the
use of conventional model is valid regardless of any effects due to its oversimplification if, and only if,
the cutting condition is on a good term with fz and vf do not exceed 0.0034Dc and 0.0033vc .