Production metrology faces challenges connected to the production industry where consumers of products expect a
standard of high quality at inexpensive costs. One approach for the next generation of production metrology devices aims
at ensuring the quality of the process technologies in every single process step, therefore measuring in-process. One
example of today's production metrology devices is the measurement of shafts in the production. Shafts are vital for
every mechanical device that translates rotational energies and the tolerances based on diameter or roundness are in the
range of microns. Those shaft measurement devices are either based on tactile measurements or on visible light which
cannot be utilized as an in-process device. A novel idea is to use X-rays instead of tactile or visible light methods to be
able to acquire robust measurement data despite of distorting debris like water, oil or dust. One focus is set on algorithms
that allow robust measurements of diameter and roundness despite of distorting debris like water, oil or dust. The
measurement uncertainty of the new method has been investigated and results will be introduced.
When integrating optic measurement systems into or next to the production line for part inspection and control of the
production process requirements for measurement devices like the measurement time and the measurement uncertainty
have to be expanded by a requirement for the robustness of the measurement system. A novel optic measurement system
will be presented which is designed for the robust measurement of roundness of shafts next to the production line which
is not influenced by residues of the manufacturing process, e.g. cooling lubricant.
The measurement system is based on projecting the shadow of a shaft onto a detector and measuring the cast edges to
derive the roundness of the shaft. The main parts of the measuring system consist of a soft X-ray micro focus tube, a
highly precise angle measurement system and a CCD-detector. In contrast to roundness measurement instruments which
are based on visible light and a telecentric optical path, new algorithms to calibrate the soft X-ray measurement
instrument are being developed because of the divergent ray distribution of the soft X-rays.
This paper will introduce the design and the main elements of the novel soft X-ray projection system as well as
algorithms needed to conduct the roundness measurements. An estimation of accuracy and precision for small diameter
shafts is presented as well as possibilities to achieve the invariance up to residues of the manufacturing process.