Fraunhofer IPK

Institute for Production Systems and Design Technology

Exploration Field Optical Inspection

In the context of manufacturing, »quality is the condition of a unit in terms of its suitability to fulfill set and predefined specifications«. In the exploratory field Optical Inspection, methods and procedures are being developed for sensor-based testing of products. These methods are designed to test continuously whether products meet the predefined specifications during production.

In modern manufacturing systems, it is often impossible to separate production and quality assurance. To ensure that complex product requirements are met and defective parts are detected as early as possible, we need to see quality control as an integral part of the production process; one that is seamlessly integrated into production lines. In most cases, this is only possible if individual manual product checks are replaced by a sensor-based automatic inspection system. Such a system also offers the advantage of allowing better documentation of the inspection process than a manual inspection.

Optical procedures play an important role in sensor-based quality control, as they are non-contact and offer the level of sensitivity required for many applications. Modern LED light sources provide an impressive level of adaptation for ­specific inspection tasks – for example, the available wavelengths allow us to adapt the quality control process to suit the specific materials inspected. If this is combined with the use of standardized software and hardware interfaces, the recording systems can be integrated into the production automation system environment with a minimum of effort.

Inspection of surfaces using line scan cameras

The exploratory field Optical Inspection specializes in the inspection of surfaces using line scan cameras. In many ­cases, line scan cameras enable simple and efficient integration of quality inspection into the ongoing manufacturing process, with a high spatial resolution in the direction of movement. We are reknowned for our expertise in the development of customized LED lighting with low total reflection and a long product life. Specially developed algorithms help us to inspect even the smallest of defects on large surfaces with minimum hardware expenses. This process can reach inspection speeds of up to five meters per second, making it possible to carry out quality control even on fast flow processes. The results are continuously documented and archived.

Ethernet-based multi-camera systems

Fraunhofer IPK was one of the first institutions in Germany to use Ethernet-based multi-camera systems. The first available GigE line scan cameras can already be found in inspection systems that our industrial partners have been using with great success since 2005. In recent years, we have not only worked closely with our suppliers to improve the reliability of multi-camera systems; we have also tailored our multi-camera systems for use in extreme conditions – e.g. using water-cooled camera housings for inspecting red-hot components.