With a 95% degree of automation, the Scania body shop in Oskarshamn, Sweden is one of the most modern vehicle manufacturing plants in the world. At the same time, the plant supports extensive customization. By the time they reach the end of the assembly line, virtually no two truck cabs are the same. So is this the Industrial Internet of Things in action? Automation products from Festo have certainly provided a solid basis.
Since 2016, premium manufacturer Scania has been assembling customized truck cabs to order – and doing so almost exclusively with the aid of 288 robots. "It's completely clear to me that a premium product needs to be built in a premium plant," explains Marcus Holm, Plant Manager in Cab Body Production at Scania in Oskarshamn. "The high degree of automation results in excellent quality, as well as good working conditions and ergonomics for our operators," he adds.
A perfect match: Panel parts are clamped in pneumatically actuated devices and welded, controlled by CPX/VTSA valve manifolds (front right). In between, the initiators: Evert Forsberg (left), Lars Kreutner (right), both from Scania, and Leif Lindahl (center) from Festo.
The robots place the panel parts on the joining stations and weld them. All the employees have to do is load the stations and monitor the machines. In any case, Swedish occupational health and safety regulations have made it impossible to use hand-held welding equipment. On the one hand, welding tools have become too heavy and unwieldy, while on the other hand occupational safety directives require a minimum distance between the welding gun and the operator because of radiation.
The banning of manual welding from the assembly workshop has benefited Scania in two ways: "It means better processes and quality," explains Lars Kreutner, Project Leader Cab Body Production at Scania in Oskarshamn. To make full use of the automation technology, Scania has set up a training division where employees learn how to use the robots and automation technology.
All the trucks that Scania builds weigh more than 16 tons. The company has built a reputation as a manufacturer of special vehicles for fire services or waste collection, for example. These niche markets alone account for hundreds of thousands of variants.
"It may surprise people to learn that we offer even more customization options for trucks than there are in passenger car production," says Evert Forsberg, Automation and Electrical Engineer in the press shop and body shop at Scania. In passenger car production, every vehicle type has its own assembly line. "We, on the other hand, assemble all of the cabs that Scania supplies on a single assembly line," says Forsberg.
At the Scania body shop Oskarshamn, 288 robots weld truck cabs together.
This means that the factory has many of the key features of Industrial Internet of Things – mass production of customized vehicles, adaptability and flexibility thanks to control technology, diagnostic capability as well as industrial energy efficiency and safety solutions. "There is a modular standardization concept for all plant manufacturers," says Forsberg. At the end of the day, plant operators need to be able to rely on proven automation products. Another objective is avoiding unnecessary stock of spare parts. All panel parts are clamped in pneumatically actuated devices, and then welded. "We decided in favor of the pre-configured Festo type CPX/VTSA valve manifolds," says automation expert Forsberg: "They deliver numerous benefits – such as the Ethernet connection and web interface, diagnostics, safety, PROFINET and industrial energy efficiency."
The CPX/VTSA valve manifold is actually the only interface to PROFINET – no extra wiring is required. The valve manifold provides diagnostic data via the automation platform CPX and that can be used to monitor the systems as part of predictive maintenance: "We can replace system components before they fail and paralyze entire parts of the system," explains project manager Kreutner.
"We were also impressed by the valve manifold's safety concept," says Forsberg. The CPX makes it possible to operate different pressure zones and to exhaust areas when intervention is required. "We can check affected system parts using mobile panels and don't have to search the entire system for errors – which can be like looking for a needle in a haystack." Furthermore, re-pressurizing individual system parts is much more energy-efficient than starting up the entire system.
Welding robots require compressed air to move the welding guns and to clamp metal sheets. Cooling water protects the welding systems against overheating. Festo delivers complete solutions for supplying compressed air and cooling water for welding guns. At Scania, they are integrated in the safety fence for ease of operation – including MS series compressed air treatment.
Integrated in the safety fence for ease of operation: ready-to-install complete solution for the compressed air and cooling water supply of welding lines, including MS series compressed air treatment.
For the static welding guns, Festo developed a pivoted arm exactly as per the specifications of Scania and ABB which brings the electrode milling device, the so-called tip dresser, to the electrodes after 150 spot welds have been completed. The pivoted arm is precisely positioned by Festo DNCE electric cylinders and is powered by an EMMS stepper motor. With this solution Festo has cut the cycle times by well over half.
The reason for this is that welding gun electrodes become blunter as they are being used and have to be milled after approximately 150 spot welds to ensure the spot welding is perfectly accurate. "Electrode milling operates on the same principle as the sharpening of a blunt pencil," explains Leif Lindahl, former Key Account Manager for Scania at Festo.
The control cabinet from Festo for electrode milling comprises the CMMS motor controller and the CPX, which communicates with the motor controllers and the primary robot controller. "Safety has also increased, since plant operators no longer have to enter the robot cells after milling to adjust the electrodes to the correct position for the spot welds," adds Lindahl.
Scania is ushering in a new era in vehicle manufacturing in Oskarshamn. As it is almost completely automated, but still allows huge flexibility right down to a batch size of 1 on a single assembly line, the body shop is already well on its way towards the Industrial Internet of Things. The new factory has set a precedent, and Scania will shortly build a similar factory at the Scania plant in São Paulo, Brazil.
Oskarshamn is an industrial town on Sweden's east coast, around 300 km south of Stockholm, with transport links to the holiday islands of Gotland and Öland. In 2017, a workforce of 2700 assembled a wide range of cabs for all Scania models here. Vehicle transporters take the cabs from Oskarshamn and deliver them to the Scania assembly plants in Södertälje near Stockholm, Zwolle in the Netherlands, and Angers in France, where they are assembled to create the complete truck chassis.