Coko: Automated Production Control of Large Plastic Parts

Coko-Werk GmbH & Co. KG has a long tradition in plastic injection molding. Established in 1926, Coko started off with a unique product – the unbreakable celluloid comb. Today, the injection molding company sees itself as a system supplier for technical plastic articles and specializes in large parts. The company uses ATOS ScanBox 6235 optical 3D measuring machine at its development and innovation site in Bad Salzuflen, Germany, to ensure efficient quality control in the production process.

Automotive engineering is part of the core business in Bad Salzuflen. Parts such as mudguards (fenders) for utility vehicles are produced on a machine with a closing force of 2400 tons. Coko also manufactures a large number of headlight housings for several OEMs. Its experts benefit from the ZEISS optical 3D measurement technology systems while managing these challenges. The full-field measuring results guarantee a faster first article inspection and targeted tool correction, thereby reducing production lead times.

“We have been using a ScanBox for efficient quality control in our production and manufacturing processes since 2020,” says Andre Gromann, Head of Metrology at Coko. The optical 3D measuring machine is equipped with industrial high-precision 3D scanners which inspect the entire surface geometry of the parts by executing non-contact scans in two working areas.

The mudguards are digitized using a standard fixture based on the 3-2-1 principle. “During this measuring job, we used a multi-part fixture as a measuring fixture in order to increase throughput,” explains Andre Gromann. Thanks to the multi-part fixture, two mudguards can be scanned simultaneously. However, not only does the device increase throughput – it also provides the metrology engineers with more flexibility.

In series inspections, the measuring job is initiated via the simple and self-explanatory Kiosk Interface of the ScanBox. Measurement and inspection programs are stored as templates in the virtual measuring room of the ZEISS INSPECT software. Users can access them in the Kiosk mode. The operator enters his name into a matrix, selects the template for the item, enters an inspection job number and initiates the scan. The inspection takes only a short while. The inspection results are then automatically migrated into Coko’s CRQ system.

Coko uses the ZEISS INSPECT software for detailed 3D data evaluations. “When inspecting headlight housings, we typically measure diameters, cylindricities and position deviations,” explains Björn Sonters, metrology engineer at Coko, and adds: “We concentrate especially on the RPS alignment and point-to-point evaluations.” GD&T evaluation is also very important in the field of plastic injection molding. Thanks to ZEISS INSPECT, it is easy to verify whether form errors are within permissible limits. “You can see the error at first glance. If the headlight socket has slight deviations, it cannot be installed in some cases,” explains Björn Sonters. Coko uses ZEISS INSPECT throughout the entire product development process (PDP) while communicating with its customers – working with 3D data has proven to be very convincing. The data quickly shows whether the product is feasible or not.

Coko has started to deeply integrate technology into its production processes. “This integration needs fast, reliable and efficient metrology systems,” as Andreas Spilker, Head of QA/QM at Coko, points out. And he adds: “Of course, we want to oversee the production process. We want to have qualified results, and most of all: We want to be fast.”