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Use in series production - alpha.si

An industrial robot loads and unloads the measuring machine for the inline inspection of rotating components. The shaft to be inspected is placed between the two measuring prods, is rotated for the measuring process and scanned by at least three laser sensors, whose measuring beams are aimed at the shaft with different orientations. This measuring procedure also enables the measurement of grooves, trigger wheels, concave contours and other special properties without special clamping device. A granite machine bed combined with integrated compensation functions guarantees high long-term stability against influences from the production environment.
Such a measuring system inspects approximately one million shafts per year.

A system for all properties

For inline inspection of shafts the complexity of the measuring task is due to the great number of properties to be inspected and the cycle time of the manufacturing process.
nokra measuring systems record all relevant parameters with the necessary precision, inline in the production cycle. For instance, it is possible to check 60 geometric properties within seconds.

The following chart shows typical values of our alpha.si:

Measuring precision (1 σ, typical values)  
Length: 0,3 µm
Diameter: 0,6 µm
Angle: 0,005°
Shape deviation: 0,8 µm
Roundness: 0,3 µm
Radial run-out: 0,4 µm
Axial run-out: 0,4 µm
Spektrum of assembly  
Length of shaft: up to 800 mm
Diameter: 150 mm
Workpiece: < 30 kg
Laser sensors  
Measurement range 20 mm
Measuring uncertainty 0,01% of the measurement range
Length/Diameter: 0,1 μm
Angle: 0,001°
Clamping devices  
Coded standardized cones (RFID or barcode)  
Hydraulic expansion chuck (optional)  

Inspection plan, technology, precision

Cope of functions of the measuring system
In order to be able to carry out constantly precise measurements nokra designed state-of-the-art measuring systems:

  • flexibility: measurement of all properties without retrofitting and
    without special clamping devices
  • absolute measuring and automatic adjustment of the measuring system
    with an adjustment shaft
  • measuring system capability, for instance in accordance with the Measurement System Analysis Standard (MSA)
  • short measuring time, thanks to high sensor measuring frequency
  • optimized laser sensors for difficult measuring surfaces
  • error-proof clamping device (RFID)
  • temperature sensors in the measuring machine enable an
    automatic adjustment to the ambient conditions
  • simple integration via Profibus interface
  • standardized data storage: storing the measuring and inspection results in the QA statistics standard
  • granite machine bed: minimized influence of temperature and vibrations, guarantee for high measuring precision and high plant availability

Measurement in the production line

Inline measurement
Thanks to the technology used, nokra systems can also be used directly in the production line under difficult conditions. Here the contactless scan-ning with a laser in combination with flexible handling systems, such as for instance robots, enables a minimization of the retrofitting and maintenance work and at the same time high flexibility for different product variants.

The measurement data provided in the production cycle on the one hand enables a complete documentation of the product geometry in the sense of the quality assurance, and it can also be directly used for optimizing process management. In this way, through feedback of the data to up-stream production plants in the sense of an integrated quality control circle the production of waste can be countered at an early stage.

Available accessories:

  • coded cones for clamping in various designs
  • reader for barcode or data matrix code
  • calibrated master parts for automatic adjustment and calibration
  • handling systems incl. gripper