Tube bending machine manufacturer Schwarze-Robitec on where the industry currently stands.

The key trends in tube bending include lightweight construction, customised machine configuration and automation. The figures provided by Germany’s Federal Motor Transport Authority (KBA) speak for themselves: Among all newly registered vehicles in Germany in the period from January to November 2021, the share of those with alternative powertrains amounted to almost 35%. The share of vehicles with purely electric drives was at around 11% of all new registrations in this time. But an increase of new electric vehicles (EVs) becomes particularly clear when looking at passenger cars. In that segment, the EV share in all newly registered passenger cars was 6.7% for the entire year 2020. This share has substantially risen to over 25% when looking at the period of January to November 2021. The effects of this shift are being felt not just by the automotive manufacturers themselves but across the entire supply chain. Lightweight construction is a major theme here, since the lighter the vehicle, the less energy it needs. And this increases the range, crucial for EVs. It also leads to a change in requirements for tube bending, with a growing need for compact yet high-performance components, such as thin-walled tubes made from high-strength materials. But lightweight materials such as aluminium and carbon fibre reinforced plastic are usually more expensive and more challenging to process than conventional steel. Cologne-based tube bending machine manufacturer Schwarze-Robitec is also witnessing a substantial increase in orders that go beyond the bending of typical round tubes. Instead, lightweight construction increasingly requires complex, asymmetrical shapes with diverse cross sections.

Traditional automotive manufacturing usually involves round tubes being bent and then turned into the desired profile shape through hydroforming. This subsequent bending process is often not possible when working with lightweight materials. Carbon fibre reinforced plastic, for instance, cannot be bent when it is cold. As such, the bending profile needs to match the geometry of the final component during the first step, i.e. when bending the tubes. In addition, applying heat is a difficult process for these materials. An additional issue in the case of aluminium, for instance, is that the material hardens in the air. This means that a prefabricated aluminium profile can no longer be bent after just a few months. Furthermore, if the desired cross section is not round, it is much harder to adhere to the predefined tolerances, especially when using aluminium. An additional difficulty posed by lightweight materials concerns conductors, with aluminium profiles and rods increasingly replacing traditional copper cables in cars. The layers of insulation cannot be damaged during bending.

Shift towards flexible configuration of tube bending machines

With the shift towards electric mobility, the traditional standard tube bending machine with predefined performance parameters is increasingly giving way to product-specific special machines that can be customised according to client needs. Bending performance, geometric measurements such as bending radius and tube length, tool installation space and software can increasingly be aligned with client and product requirements. This shift is already ongoing but will intensify, predicts Schwarze-Robitec Managing Director Bert Zorn. “To be able to realise these sorts of projects, systems suppliers need to not only have the necessary expertise in bending technology but also the requisite knowledge and experience in tool and process design,” Zorn explains. “This is the case from the design stage right up to the start of series production and production support.” Complex tool shapes are needed to produce aluminium profiles with different types of cross sections, for instance. The development and correct design of such tools thus becomes increasingly important. Furthermore, when carbon fibre reinforced plastic is used, there must be a possibility of only partially applying heat.

Focus on efficiency and short cycle times

Conventional combustion engines still account for the lion’s share of automotive production, however, and therefore remain of huge importance for manufacturers of tube bending machines. The growing cost pressure sweeping across the automotive industry is also being felt throughout the entire supply chain. Short cycle times, maximum speed and a high degree of precision are the order of the day. Companies aiming to remain competitive need to use resources efficiently. This not only includes time and material resources, but also human resources, the individual employee who plays a central role in the manufacturing industry. In this field, user-friendly and reliable processes are a key factor in boosting cost-effectiveness.

Manufacturers of tube bending machines need to respond to the challenges of their target industries by supplying high-performance machines that are tailored precisely to their customers’ needs. To achieve this, Schwarze-Robitec is relying on multilevel technology, for instance. Used in combination with customisable multi-radius bending tools, this technology facilitates simple and precise bending with only short lengths of tube between individual bends. The effect of this is clearest to see when different radii, bend-in-bend systems or complex tube systems are being manufactured, as even a few seconds saved per component can have a huge positive impact on production efficiency.

Another key aspect when it comes to tube bending efficiency is the interaction between operator and machine. The technology must support users wherever it can. For example, the integration of bend former retraction – with bend former and swing arm operated separately – as standard enables users of Schwarze-Robitec machines to adjust and position a wide range of tube geometries during the bending process without any problems at all. The most significant benefit, however, comes from Schwarze-Robitec’s very own smart NxG control system, which continuously and fully automatically monitors the interaction of axes and optimally coordinates their movement. While one bend is still in progress, the axes are already being prepared for the next steps. The Cologne-based manufacturer’s solution therefore reduces production times by 20 to 40% depending on the component and the desired tube geometry.

Automation and integration of processes beyond bending

In view of the shift toward alternative powertrains, the frequently used buzzword ‘automation’ is more relevant than ever. Manufacturers of tube bending machines need to focus on extensive automation and increasingly integrate work processes that go beyond bending. This is not just the case for tube bending processes in large-scale series production, but also increasingly for very low volume series production. In (fully) automated tube processing, the various stages of the process are reliable, error-free, repeatable, and fast, ensuring that bending results are consistently of the same quality. Upstream and downstream processing steps are also integrated into the fully automated bending cell – from cleaning, assembly and end-forming to tube measurement. Handling devices such as robots and additional systems for tube feeding and unloading are integrated, too. The primary task is to precisely analyse which processes are the perfect fit for the application in question. For example, depending on a customer’s requirements, a belt-loading magazine, chain magazine, lifting conveyor or a loose material conveyor might be the right system for the tube feeder. The optimal component must be determined for each individual process. These components can then be put together to form a complete system that optimally meets requirements. This system, along with all process steps, is then controlled centrally via Schwarze-Robitec’s NxG control system in combination with the master computer system.

Even though each additional process step makes the process chain longer, the user does not have to experience any delays as cycle times generally remain the same. The increased complexity of such an automated system means there are greater requirements in terms of control and the integration of bending cells into existing production chains and company networks. That is why it is also important that tube bending machines are already implementing existing and future industry 4.0 technologies. Schwarze-Robitec guarantees the compatibility of the various systems within a fully automated system by using precisely defined interfaces to individual components that are interconnected via a bus system.

“Companies that act flexibly by tailoring their machines to special customer requirements can now work with this strength, as the shift towards electric motors in the automotive industry is driving a change in parameters,” explains Schwarze-Robitec Managing Director Bert Zorn. “Suppliers such as manufacturers of tube bending machines need to be able to respond with flexibility and speed and devise new production methods.”