Multiple 3D measurements of large aluminium die casted automotive parts (gearbox cover)

LTH Castings is Slovene company with production sites in Slovenia and in SEE. The company specializes in manufacturing a wide range of high-specification automotive components, such as transmission and engine components, steering and brake systems components.

In order to comply with the customer's requirements, the client required a 100% inline control which consisted of a number of optical 3D measurements of the casted part as well as visual control of the machined surface for porosity.

Our challenge

• It is optically demanding to measure large parts (size range ~300mm) with tight tolerances of 0.05mm–0.2mm within a short cycle time (required cycle time was 20s).
• Achieving the necessary illumination of the piece was problematic due to the shape of the object, as some parts had limited accessibility and consequently were not reached by enough light; special approach needed to be devised.
• The reference base from all measurements was "virtual" – such as virtual planes/axes/points (for example, one of the references was the centre of the central, inner hole) and the measurement of such parts requires either very expensive high megapixel area scan cameras and lenses or a different, "smarter" approach.

Features

• Custom made, inline, optical coordinate measurement machine
  • Measured parameters: surface flatness, parallelism, perpendicularity, angularity, positions of inspected features, surface inspection for porosity (defect analysis according to the OENM standard Daimler-Benz standard DBL 4949)
• Number of optical measuring sites: 2
  • A special illumination approach was developed, including usage of custom made lights
  • A rotational scanner to measure the central bore was custom developed in house.
  • Custom SW algorithms were developed for realizing referential virtual bases.
  • Tolerances:
  • Cycle time: inline (20s).