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.
Metrology is the key to an economically feasible production of fiber-reinforced composites in the field of automated tape
laying, applying a novel laser light-section sensor system (LLSS) to measure process quality and feed back the results to
close control loops of the production system. The developed method derives 3D measurements from height profiles
through an in-process surface scan by the integrated LLSS. Gaps, overlaps, misalignment and defects of the composite
tapes are detected during their lay-up and consolidation by comparing the measurement results with a CAD/CAM model
of the lay-up. The height profiles are processed with a novel algorithm based on a non-linear least-square fitting to a set
of sigmoid functions to ensure sub-pixel accuracy.
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.
Recently, X-ray computer tomography (XCT), as already established for medical applications has been utilized for
production metrology. The ability to perform non-destructive testing methods on prototypes provides a huge potential for
the reduction of inspection time for first sample release testing. While today's XCT devices focus on transilluminating
the object and generate 4D-voxeldata, the possibility to focus only on the edges of objects and therefore on the cast
shadow of the object on the detector to measure form tolerances is presented.
This paper will focus on edge detection algorithms as well as new methods to calibrate a soft X-ray projection system to
be able to measure form tolerances. In contrast to form 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. The advantage of soft X-rays, compared to visible light, is that they
are not influenced by residues of the manufacturing process, e.g. cooling lubricant, which allows a robust analysis of the
outer object form. An algorithm for robust edge detection will be introduced and the correlation between the precision of
the edge algorithm and strategies developed to calibrate the shaft measurement instrument are shown, which is crucial to
reach the targeted low measurement uncertainty.