When something goes wrong in industrial production processes, this will very quickly lead to high costs. Thus, companies have a major interest in monitoring production processes. While some questions can be satisfactorily addressed using camera and laser systems, other production processes require sensors with capacities that go beyond those of optical systems. Radar sensors offer an ideal solution here: They are not only capable of measuring under difficult environmental conditions, for instance with limited visibility, but also of looking through dielectric materials to detect defects. Fraunhofer FHR's Business Unit Production offers the necessary expertise for all questions relating to radar.

Checking Production Processes for Metals

One interesting field of application for radar systems are rolling mills in the steel industry. Here, steel slabs with temperatures of 800 to 1,000 degrees are rolled to sheet metal. The challenge in the process: In order to separate the scale created in the production processes, the slabs are sprayed with water – the steam that rises up then complicates the use of optical measuring systems. This is different for radar systems, more precisely millimeter wave systems: They are capable of accomplishing the task extremely well, as different projects of the Business Unit Production have shown. In general, the following applies to production processes: The earlier defects are detected, the cheaper it is to remedy them. For example, if a car door has a dent, it can be easily sorted out in the beginning. But further along the value chain, each additional production step costs hard cash. Panels designated to be made into car doors are also frequently checked visually for defects. However, a feasibility study of the Business Unit Production provided the following result: A millimeter wave sensor allows for the reliable detection of even the smallest of scratches. In the long run, this could even provide 100 percent control.

Non-destructive Testing for Food, Plastics, and Composites

Sometimes, it makes sense to not only check the products superficially, like for car doors, but to also have a look inside – without destroying the objects. Radar makes this possible as well, at least for dielectric materials. One of the applications is food testing: This involves detecting foreign matter that has accidentally gotten into the food in the production process. Radar is also a promising solution for non-destructive testing of additively manufactured components, i.e. 3D printed plastic. In addition, radar examinations offer benefits during the lifespan of a product, for instance for composite materials like the ones used for the rotor blades of wind turbines.

Looking to the Future: Smart Factories and Additive Manufacturing

What will production look like in the future? One possible vision is the smart factory, where the supply of components and production are run intelligently and autonomously. However, autonomy always starts with the sensors: This is where the Business Unit Production offers the required expertise as well as the capabilities to develop individual solutions for safety-critical aspects such as machine safety.

Additive manufacturing – where components are manufactured in a 3D printer – is another future trend. For instance, this allows for antennas to be printed or component concepts to be implemented that could not be manufactured before. Combined with high frequency technology, additive manufacturing opens up numerous new fields of application: For example, the antennas could be integrated directly into functional components of a production machine, with the components working like antennas in places where they are penetrated by the radar wave.

Technical contributions from the business unit

Using radar to check steel sheet thickness

Sabine Gütgemann


Quality control in production: Radar-based surface imaging

Dr. rer. nat. André Froehly


Using radar to detect foreign objects in food

Daniel Behrendt