Abstract. The efforts for actualizing a breakthrough in technology and rising the level of the sustainability of manufacturing systems via implementation of I4 and I5 have given significant impetus to the concept of the Digital Twins. In the context of the rolling industry, a propitious version of a Digital Twin is a replica of the calibration (roll pass design). The calibration is an embodiment of the instructions for the realisation of the rolling process, including design, monitoring, control and maintenance. An aspect of fundamental importance in the calibration and in the design of digital twins is the mathematical definition of the geometry of the deformation zone and, in particular, digitizing the incoming and exiting contours of the rolled solids. The proposed method for digitizing the pass morphometry opens the gate for mobilizing the existing computing potentials and analytic theories for improving the sustainability of rolling systems.Keywords: calibration (roll pass design), calibre, groove, deformation zone, digital twin, Chebyshev polynomials.