Casting Plant and Technology International 19 Nr. 4, 2003.
Modern foundries manufacture high-quality castings and achieve high levels of productivity. To realise either aspect - high quality and high throughputs - to an equal degree requires efficient production processes of a high constancy and, at the same time, mechanisms capable of identifying inadmissible process deviations quickly and reliably, so as then to revert immediately to the desired process status of high productivity and high quality. In high-wage countries, such processes are economically realisable only in largely automated form. Given their historical evolution, most automation solutions tend to be dominated by actuators (robots, manipulators), while sensory aspects often receive too little consideration. It is here, in particular, that there is a considerable potential for optimisation, which, if opened up, would yield major qualitative and economic benefits. The present article deals with sensor technology capable of automatic visual inspection, specially for castings. The harsh ambient conditions in foundries place exacting demands on optical systems. Such systems must, on the one hand, be robust enough to perform their functions reliably on a continuous basis while; on the other hand, the sensitivity with regard to the inspected object features should not be impaired. To satisfy either requirement, special importance has to be attached to representative source data, which contain as much useful and, at the same time, as little unwanted information as possible. For this reason, the examples of use discussed in the following all operate with specially adapted lighting systems and certain "optical tricks" to generate images of a high task-specific quality. (Example: V8 cylinder engine crankcase casting.)