Robotic applications are the state of the art in numerous manufacturing sectors. In the cold rolling industry they aren’t yet as widely used as in other industries due to the manufacturing process and the size and weight of the coils. Waelzholz, however, is actively driving the introduction of automation technology at the company with a global investment program. The reason is an increase in quality and flexibility in many key details.
As a technological leader in the field of cold rolling, systematically advancing its production technology is a top priority for Waelzholz. One component of this strategy is a global investment program dedicated to robotic applications. Now if you think about industrial robotic applications, you quickly conclude that the main reason for their use is to increase the efficiency of processes. For Waelzholz, however, the focus is primarily on the factors of quality and flexibility. As Dr. Ernst-Martin vom Bovert, Head of Logistics and also responsible for the introduction of robot technology at the company’s German site in Hagen, explains:
“Automated processes have been around in the cold rolling industry for a long time. Yet there was never much demand for conventional robotic applications in the past – primarily due to the weight of the products. This has noticeably changed in the last few years, in part due to higher standards on the part of our customers.”
Global automation strategy
Customers’ quality standards have risen across the board in recent years, and this is set to continue. In addition to meticulously maintaining material properties over multiple batches of deliveries, it is also a matter, for example, of precise and flawless edges, particularly in the case of very thin dimensions, as well as impeccable strip surfaces. In addition, customized packaging solutionsrequire a considerable degree of flexibility. This is one area in which robotic applications can make full use of their capabilities. Lukas Okon, project manager responsible for the introduction of the first robot at the Plettenberg plant, explains the challenge involved:
“We already started developing the robotic application at our plant back in 2018, because the use of robots is very challenging when it comes down to the details. Laser detection for positioning is one example of a such a challenge – because our high-gloss steel strip couldn’t be detected using conventional methods, we ended up developing a special solution for this purpose in collaboration with the supplier.”
Today, the company already has robots in use at its German plants in Plettenberg and Kabel and the Brazilian production facility in São Paulo. As part of a global automation strategy, further applications will be rolled out at Waelzholz plants across the globe on the basis of the experience the company has gained thus far.
The packaging line in use at the narrow steel strip mill in Hagen illustrates the potential of the robotic applications Waelzholz is developing. At this site, the coils, which can weigh around 250 kg (551 lbs) depending on the design, used to be picked up from transport racks manually using a magnetic lifting system and stacked “eye to the sky” – i.e. lying flat – on pallets. In addition, the layer pads necessary to protect them were manually placed between each of them. Today, this task is performed by a robot that can alternately feed two workstations within a cell. In this process, the robot removes one coil at a time from a rack containing up to ten coils with the help of a magnetic gripper. While doing so, the gripper centers itself automatically and then places the coil on a pallet with pinpoint accuracy. As Dr. vom Bovert explains:
“A laser sensor system measures the coil being picked up, ensuring that it is gripped very precisely by the inner hole. And when setting them down on a pallet, the robot positions the coils on top of each other with extreme accuracy. This high degree of precision is particularly important to us, because it makes the process extremely material-friendly, ensuring that the edges and coil surface don’t get damaged.”
A similar solution is also in use at the Plettenberg plant. Here, the company is simultaneously working on another automation solution: integrating a robot into the process of slitting the steel strip. What makes this so special is that the robot will automatically remove the required set of blades from the blade stand, carry out the slitting operation, and check the blade sharpness, among other parameters, during the process.
Whether special wooden slats, corrosion-resistant overseas packaging, or other customized packaging elements, the combination grippers developed for Kabel and Plettenberg are designed to meet a wide range of requirements. As Dr. vom Bovert explains:
“The standard version of the robot in use at the Kabel plant, for example, is equipped with a four-arm magnetic gripper. We then had four mechanical parallel grippers and four vacuum grippers mounted to the gripper head, meaning that we can now use all three gripping techniques – magnetic, mechanical, and pneumatic. This means we have a great deal of flexibility and can respond to different needs.”
Another advantage is that despite the combination gripper’s total weight of several hundred kilos, the robot can move and stack the coils with a swivel radius of 2.80 meters. Robotic cells like the ones Waelzholz uses aren’t available off the rack – the company developed them together with robotic automation specialists and a great deal of its own process expertise.