Robots are used in a flexible manner since they are provided with several tools
With the CF and XF series, DAF Trucks constructs state-of-the-art transport vehicles that satisfy all modern requirements in terms of safety, performance and comfort. Truck cabs are assembled in the DAF body factory in Westerlo – a highly automated process that involves the deployment of FANUC robots for handling, bonding and spot welding.
The factory where the cabs are assembled consists of dozens of workstations, where various steps of the production process are carried out. The process differs from classic construction in the automotive industry and cycle times for trucks are a lot lower, so each station can carry out several operations. This has specific consequences for the robots, as they are deployed in a more flexible manner given that they have several tools available to them. For example, the rear panel of the XF cabs is assembled in a cell, where the robot has a docking station to swap its handling tool for a spot welding tool. This enables a single robot to position the components and secure them after visual inspection, and then a second robot in the cell helps with spot welding. As such, the method of automation for each cell is optimised in order for the required tasks to be completed within the predefined cycle time.
The main advantage is reliability
The collaboration between DAF Trucks and FANUC dates back to 1991, when the first robot for bonding components was put into service. It should be noted that this robot, which has now celebrated its 25th anniversary, is still operational. It is used for bonding external components of doors, which cannot be done by spot welding, as traces of point welding would otherwise be visible on the outside.
“The robot is living proof of the reliability of FANUC,” says August Creemers. As Head of Engineering, he is responsible for implementing new projects at DAF Trucks in Westerlo. “FANUC’s main advantage is reliability. When a robot comes onto the market, we can guarantee that it is reliable and that it meets the required specifications. Our first task is to ensure that production is running smoothly and that all equipment is maintained in an efficient state. As far as FANUC robots are concerned, we don’t have to worry about this.”
Alfons Verheyen is the Maintenance Engineer responsible for preventative maintenance and confirms this story: “The reliability of the robots also has a downside. As there are few or no problems, we don’t routinely work with the robots. So when something needs adjusting, for example on the oldest robots from 1991, it always takes a bit of searching.”
Alfons still remembers the introduction of the first two FANUC robots, 25 years ago. “We were given a training and full documentation with the robots. Programming was carried out with Karel, a language closely associated with Pascal. At that time, when other robots were still being programmed in Basic, this was revolutionary.”
The programming of the bonding can be difficult to achieve. It is necessary for the robot to make allowances for the delay that occurs when starting and stopping the dispensing of adhesive. When a trajectory includes a curve or an angle, the robot must be sped up so that the quantity of adhesive applied remains constant.
We have a preventative maintenance agreement with FANUC, which also continues to look after the programming. The basics remain the same; however, when new models are introduced, the programming must be adjusted to the new dimensions.”
While most robots in the cab factory are deployed for spot welding, they also carry out a number of handling tasks. For example, nuts must be moulded onto the front panel. They have a sharp edge, which is flattened in the mould in order to secure the nuts to the panel. A FANUC R-2000iB fits the nuts and then holds the plate in position to mould the nuts. This process requires a tolerance of 0.5 mm, which is easily achieved by the robot.
Subsequently, brackets have to be secured to the rear panel. These are manually inserted before the panel is brought into the production cell. A visual system in the cell checks if all the brackets are present before FANUC robots start spot welding.
Three robots work simultaneously on the spot welding in the assembly cell for the XF cabs. To reach into the back of the cab, the M900iA has an extended arm. The process is made complete by two R-2000iB robots.
“A total of 65 robots are busy at work in the body factory, including a large number of FANUC robots,” says August Creemers. “The flexibility of the robots allows us to continuously develop automation. FANUC’s main strength is reliability: periodic maintenance is carried out on the robots, but other than that, we don’t seem to have any issues. The machines are robust and precise, enabling us to continuously deliver high-quality products to our factories in Eindhoven and Leyland, where further finishing of the trucks is carried out.”