Fusion of geometric and thermographic data for the automatic inspection of forgings and castings

Many workpieces produced in large numbers and having a large variety of sizes and geometries, e.g. castings and forgings, have to be 100% inspected; on the one side, geometric tolerances need to be examined, and on the other side material defects, surface cracks have to be detected. In the paper a fully automated non-destructive testing technique is presented, whereby the workpiece is continuously moved and during this movement two measurements are carried out: first a thermographical measurement combined with inductive heating, where an infrared camera records the temperature distribution at the surface of the workpiece in order to localize material defects and surface cracks. In the second step a light sectioning measurement is carried out, to measure the 3d geometry of the piece. With help of registration the data from the two different sources are fused (merged) and evaluated together. The advantage of this technique is, that a more reliable decision can be made about the failures and their possible causes. The same registration technique can also be used for the comparison of different pieces and therefore to localize different failure types, compared to a 'golden', defect-free piece.