SaarGummi: “We have grown along with our inspection systems”

When you produce millions of meters of endless sealing profiles per year, you have to pay special attention to quality control. Since 2005, automotive supplier SaarGummi has relied on the expertise from measuring technology specialist PIXARGUS.

In hall 33 of SaarGummi’s facilities in Büschfeld, Germany, endless sealing profiles to be supplied to the big players in the automotive industry are wound on reels that can accommodate up to 1,400 meters of the product. Throughout this process, the quality of the extruded profiles is continuously checked with PIXARGUS inspection systems. Later, at the carmaker’s manufacturing lines, the profiles are paid off fully automatically and cut to the lengths required for the specific car model. While the car doors are being held in position by heavy-duty robots, the exactly fitting seals are glued onto the doors in a fully automatic process that requires no operator intervention.   

“With the idea of producing sealing profiles in an endless mode, we have taken process automation to the next level, both for us and for our customers in the automotive industry,” says Christian Kast, Director Global Product Automotive, and, in 2006, inventor of the endless technology at SaarGummi. Implementing the technology was a very challenging task, as the elastic rubber profiles were much more difficult to handle, process and convey by our machines than rigid products. Today, almost 50 million meters of endless sealing profiles are produced every year at the Büschfeld facilities in the north of the German Saarland region. SaarGummi’s customer base includes the carmakers Daimler, BMW, Ford, VW and Seat and utility vehicles manufacturer Scania.

PIXARGUS has been on board as quality control experts ever since the endless process was introduced at SaarGummi. “Assuring quality over a length of 1,400 meters called for a non-contact inspection process that ideally would work in an inline process,” recalls Christian Kast. This is exactly the specialism of PIXARGUS, supplier of camera-based digital inline inspection systems that easily integrate with production processes and existing corporate network environments.

Meanwhile SaarGummi uses Two-in-One systems of PIXARGUS’ ProfilControl series at four of its manufacturing lines. These systems are called “Two in One” because they can check the surface and the contour of the profile simultaneously in a continuous process. “The measured data is instantly available in our systems,” explains Kast. “We also have to assure that the adhesive tape at the bottom side of the profile is properly aligned and in the correct position. Here our customers specify extremely tight tolerances of a few tenths of a millimeter!”

Inspection of the surface is just as challenging. “Our customers are very demanding,” Kast continues. “The sealings do not only have to perform a function. As they will be visible when installed in the car, also the surface quality requirements are extremely high.”How high exactly is agreed with each individual customer based on defined threshold patterns. “Jointly with our customers, we define beyond which limit a speck is a defect and a product is out of spec.” The next step then is to translate the agreed tolerance range into both the process world of SaarGummi and the defect detection software of the PIXARGUS inspection system.

Christian Kast is impressed with the ease and precision with which the roughness parameters can be set in the PIXARGUS system. These settings determine the contrast ratio and accuracy of detail of the cameras. “Ease of operation was one of the reasons why we decided in favour of PIXARGUS. We did not want a technology that would require us to do the programming,” Kast recalls. “We were looking for straightforward, easy-to-use systems.”“

On three lines, SaarGummi uses the double-strand extrusion process to produce endless sealing profiles, traded under the name “SealMatic”. This means that the sealing profiles are extruded symmetrically back to back. To be able to measure the strands separately from each other, PIXARGUS enhanced its ProfilControl 7 system with a dedicated frequency generator, which measures the speed of the extruded strands and sets the image processing rate for the optical sensors accordingly.

Scene change. Jan Müller is sitting in front of the computer in his office in Büschfeld. Production hall 22 is his territory. Here, SaarGummi produces cut-to-length sealing profiles. “We make all sorts of seals used in a car body,” Process Engineer Müller tells us in a video call. Here too, four ProfilControl systems are in use at four production lines. PIXARGUS has been SaarGummi’s measuring technology partner since 2005. Müller shares his screen with us. We are taken “live” to the quality control process for roof frame seals and see the PIXARGUS ProfilControl 7 DualVision in action: the surface inspection details are shown on the left, and the dimension measurement process on the right part of the screen.

Eight cameras are scanning the rubber profiles, reliably detecting irregularities such as specks, blisters, lump defects and residues from flocking. Should the C-lip be too short, for example, the dimension measurement system will immediately send out a defect notice. “Thus, I can see at a glance where a defect originates from and can take action immediately,” explains Müller.

Camera 3 has just spotted a fault at running meter 2870. “Some kind of impurity”, says Müller. The system has already marked the affected area. At the packing line, the personnel will see the yellow mark on the profile surface and dispose of the affected product. In the right part of the screen, we see the nominal contour of the profile being measured. It is overlaid with graphs that are highlighted and pop up erratically. ”This is how the system indicates which values are currently being measured in which area of the profile, enabling us to see at any time whether our product is within the specified tolerances.”

Müller has already completed two training courses at PIXARGUS. At SaarGummi, he is the person in charge for the inspection systems, from set-up, trouble shooting up to the installation of new inspection programs. Also data management and the analysis of defect images belong to his duties.

“We handle trouble shooting and problem solving very autonomously here,” Müller adds. At one of the production lines, the original ProfileControl 4 system from 2005 is still in operation. The youngest system in place is of the latest ProfileControl7 series. It is of the same compact Two-in-One design as the systems in use at the endless lines, measuring both the surface and the contour with just one sensor. “A special feature of the latest PC 7 model is its exceptional compactness.” In the production world every single meter produced counts. “We have actually grown along with our inspection systems,” says Müller gladly, switching us back to our video call. The 30-year-old is happy. Everything is running smoothly in hall 22.

At PIXARGUS, we develop measuring systems of increasingly more compact design, says PIXARGUS Sales Director Michael Frohn. Assistance systems, such as our automatic lighting control and the auto focus, reduce the initial set-up effort to a minimum even today. “Our systems are virtually self-adjusting,” explains Frohn. This makes them very easy to integrate into the production line or use them between several lines. “Especially in the automotive industry, production cycles become shorter every year," Frohn continues. “The producers are feeling pressure to increase efficiency while keeping their extremely high quality level.” The PIXARGUS software is also designed to provide the flexibility needed in innovative manufacturing processes. “The customer tells us what he wants the camera to see, and we will configure the system accordingly in almost no time," Frohn states. PIXARGUS is proud of the longstanding partnership with SaarGummi. “Collaborating with our customers on a trustful basis is very important to us.

IMG 1: Automotive supplier SaarGummi produces almost 50 million meters of endless sealing profiles per year at its facilities in Büschfeld, Germany. The production processes are characterized by a very high automation level.
IMG 2: Integrated into the four production lines at SaarGummi in Büschfeld, Two-in-One systems of the PIXARGUS ProfilControl series inspect the surface and the geometry of the profiles in a simultaneous process.
IMG 3: At the carmaker’s manufacturing lines, the profiles are paid off fully automatically and cut to the lengths required for the specific car model.
IMG 4: The PIXARGUS systems also check whether the adhesive tape (red) is correctly aligned. “The tape must sit exactly in position, within a tolerance range of only a few tenths of a millimeter," explains Christian Kast, Head of SaarGummi’s development department.