Defect Detection on an Edge

When an edge has been detected, a scan for existing defects can be carried out. It shall be understood that the test edge and the required defects are explicitly defined. This task is not as trivial as it might seem at the first glance. Sometimes, it is difficult to define the difference between a defect and regular deviation of an edge. In other cases, the form of the required edge is unknown and it cannot be definitively defined by any mathematical curve. Then, one would have to use adaptive methods of edge inspection which can ensure a dynamic edge detection as well as a dynamic defect detection. To illustrate this, a defect detection on a rather simple edge is presented. For edge detection, a light-and-shadow image can be used, which is discussed in this book, but many other methods can also be applied, such as the triangulation technique [28]. For example, this can be done on a manufactured edge of a plate-shaped or disk-shaped test part that is being conveyed by or rotating in front of the capturing device during production process. The detection technique has to correspond to the production process, as well as to the test edge. The most important thing is that this method has to ensure a complete capture and a seamless inspection of an edge quickly running by as a continuous surface edge.