Measuring techniques suitable for verification and repairing of industrial components: A comparison among optical systems

Abstract On-machine verification is increasingly demanded in modern industry, due to the simultaneous necessity of high quality product and reduced time for production and verification. At the time being, contact probe systems are considered the most reliable ones, but they have many drawbacks, especially when they are used to measure free form surfaces in scanning mode. Optical techniques have the great advantage to acquire large amounts of points in very short time, and they can be used for several applications: from dimensional verification of manufactured products to the inspection of very expensive damaged parts for repairing processes in the aerospace industry. Although, they are affected by many kinds of error and they are very sensitive to the reflectivity or translucency of the sample. In this paper, a comparison between optical techniques potentially suitable to be implemented in on-machine dimensional verification is reported. The comparison involved two laser scanners, one structured light scanner and a photogrammetry-based scanner. The comparison was conducted through a free form reference object realized by the NPL Institute, with 150 × 150 × 40 mm3 of total volume.