Research and Development in Measurement and Testing Technology

Inspection of Car Wheel Dimension and Shape Tolerances

The quality of wheel geometry is a factor crucial to the driving comfort and safety of motor vehicles. Quality is evaluated based on functional geometric parameters for wheels’ bead seats, center bores, bolt holes and mounting flanges. Conventional methods of inspection that ascertains position, shape and orientation tolerances are predominantly tactile. Contact with scanned surfaces can affect wear and speed adversely.

On the basis of its OptoInspect 3D technology, the Fraunhofer IFF, in cooperation with industry partners, developed a non-contact measurement system that eliminates the drawbacks of tactile inspection and inspects relevant geometric parameters of car and truck wheels quickly and fully automatically.

Measurement Technology

The object geometry is scanned optically and without contact. The laser sensors employed function based on the principle of triangulation (laser light-sectioning and point triangulation). The sensors are configured as a cluster and measure data in a common coordinate system. A motion system consisting of translatory and rotatory axes adjusts the sensors based on the type of component and guides them over the object surface, thus scanning it. A digitized point cloud of the component surface is produced.

After they have been preprocessed, the data are segmented. Geometric primitive such as planes, cylinders and spheres are adjusted by numeric approximation based on the data of individual shape elements, e.g. edges, bores or partial planar areas,. A component coordinate system for the wheel is established from the primitives’ parameters. Then, the desired dimension, shape and position parameters can be determined in the coordinate system.

Results of Measurement

• Bead seat and center bore
  • bead seat diameter, circumference and eccentricity
  • radial and axial runout and bead seat harmonic
  • center bore diameter
• Mounting bores and mounting flange
  • bore angle and radius
  • position tolerances
  • pitch diameter
  • evenness of the mounting flange

The system is flexibly upgradable for other parameters. It is suitable for use directly in manufacturing and facilitates 100% quality assurance.