It always starts with a blank sheet of paper. The customer sketches out their requirements - perhaps a system for quality inspection, an assembly machine or another special machine. The engineers at Aumo then develop a concept and a design, and at the end of this process, a finished system with a complete service such as commissioning and maintenance is delivered. "We only build custom-made products," says Ben Rösler, Project and Sales Manager at the plant manufacturer in Radebeul and son of René Rösler, who founded the company in its current form in 1990 and also manages it. Customers primarily include automotive manufacturers and their suppliers, the aerospace industry, plastics processors and manufacturers of products for mechanical engineering, medical technology and the semiconductor industry.

Simple part, complicated test

One experienced company is SchoPlast Plastic, which was founded in 1992 but goes back to a state-owned company from the early 1970s. Aumo developed a system for the quality control of central plates for sockets for the successful producer of mainly thermoset plastic parts for electrical installations in Bischofswerda. These can be found dozens of times in every household. The visible plate, which the electrician installs in large quantities, must undergo a complex inspection after the manufacturing process, as the premium customer places extremely high quality demands on these covers, which are visible everywhere. This includes the dimensions and precise adherence to the outer contours. The detection of the smallest surface defects such as scratches and impurities is particularly challenging.

SchoPlast produces ten million of these central panels per year, and each one was previously inspected by hand and eye - an enormous effort and the real reason to relieve people of this strenuous task and leave it to a machine in future. Aumo was therefore asked whether this task could be automated. The system, which has been running at SchoPlast since April 2018, conveys two central panels per cycle from a container and places them next to each other on a complex transport system. They then pass through several stations where they are inspected. Apart from two tactile measurements to determine the material thickness and the so-called pot dimension, all other tests are image-based. There are four measuring boxes with a total of ten cameras and various area and ring light sources as incident or transmitted light. The parts are automatically moved and turned between the boxes in order to check all sides. At the end of this inspection process, the central plates are output sorted according to good parts or defect type.

Open system preferred

The ten Baumer cameras also contribute to the success of the automation solution. One reason for this is unspectacular: Baumer's Vision Competence Center is only a 25-minute drive from Aumo. Baumer uses profile systems and components from Aumo for the construction of production and testing stations, so they knew and trusted each other. But there are other reasons too. "We deliberately looked for an open system that has standardized connections for lenses and data lines and outputs grey images," emphasizes Rösler. "Other manufacturers only offer complete systems, which was too inflexible for us."

With more than 90 models, the CX series from Baumer offers GigE and USB 3.0 cameras with modern global and rolling shutter CMOS sensors. © Baumer

In contrast, the USB 3.0 model VCXU-53M from Baumer, which can be connected to a 35 mm lens and has an aperture of 1.4, was a perfect fit. The cameras use a Python 5.3 megapixel global shutter sensor from ON Semiconductor and deliver excellent image quality at up to 73 images per second. In the system at SchoPlast, the cameras take an image every 3.67 seconds with an exposure time of between 0.125 and 0.5 milliseconds. The cameras supply their data to two industrial PCs, which also control the lighting. Software developed by Aumo runs on the computers for evaluation. The results are fed directly into the quality management system at SchoPlast. Even years later, the measurement results can still be retrieved, for example in the event of an accumulation of defects.

Aumo uses the VCXU-53M not only for the inspection system at SchoPlast. The Baumer cameras are now also used in systems for two other customers to detect contours on workpieces. "We opted for this camera model because it offers exactly what we need," says Rösler.

Temperature under control

Two turning units rotate the socket plates so that the rear side can also be checked. © Aumo

Among other things, the cameras have excellent temperature management. Before commissioning, there were concerns that the cameras would get too hot in the veritable flash inferno in the measuring boxes and could exceed the maximum permissible operating temperature of 65 °C. However, the diagnostic status of each camera is constantly transmitted. However, the diagnostic data on the operating status, which each camera continuously transmits, gives the all-clear. The temperature reaches a maximum of 56 °C. This also eliminated the issue of active cooling, which would have made the system more complicated and more expensive.

"The project manager at SchoPlast was quite amazed at our clever solution," says Rösler. "We don't just want to sell our solution, we always look at the customer's requirements from their perspective."

Nicole Marofsky and Volker Zipprich-Rasch, Marketing Communication at Baumer's Vision Competence Center / am