Move your next-generation designs forward with Sika.

Now it’s possible to assemble bus roofs 90% faster with 25-30% less weight and just a fraction of the assembly staff. By bonding lightweight composite roof modules directly to the vehicle’s steel body, manufacturers can save materials, weight, and time, all while meeting the highest OEM safety and performance standards. Discover how Sika’s innovative adhesive assembly solutions can help you overcome the limitations of traditional mechanical fastening and move your business forward.

In the fast-changing landscape of commercial vehicle manufacturing, design paradigms are changing. New hybrid platforms, large modular components and mixed-material constructions are all transforming the way vehicles are designed and built. At the same time, experienced welders are in short supply, while material costs continue to rise. Sika’s bonded bus roof systems tackle these challenges head on, enabling lighter buses that can carry more passengers while requiring less time, material and effort to assemble.

Sika Industry - Moving Forward

Accelerating Production

Traditional construction methods, such as welding, often entail prolonged production times and labour-intensive processes. For Van Hool, an independent bus manufacturer using traditional body-in-white design with several metal segments joined by welding and bolts, this amounted to a 24-hour production process with three shifts and several workers on the line. 

Instead of using six line workers to assemble and mount individual roof parts, Van Hool decided to explore the possibilities of a new structurally integral composite sandwich rooftop which could be mounted in a single piece. Standard adhesives were considered but were deemed unfeasible due to their short open time, which would require six workers to apply adhesives simultaneously, and long curing time, which would add up to twelve hours of unproductive waiting time. 

Fortunately, Sika’s specially formulated Powerflex and Curing-by-Design technologies eliminated these obstacles. Using cartridges or a pumping system, the adhesive can be applied by just one or two people. And faster curing means that subsequent assembly steps can continue less than two hours after mounting – amounting to a full 90% time savings.

Moving Forward

Enhancing Performance and Safety

Unlike conventional adhesives, which are often compromised by thermal expansion in extreme temperatures, Powerflex adhesives offer heightened toughness and impact resistance across a temperature range of -40 °C to 100 °C. By uniting different materials and optimizing stress distribution, these adhesives provide consistent performance across a wide temperature range, ensuring flexibility at lower temperatures and stiffness at higher temperatures. As extensive rollover impact tests and FEM simulations clearly show, the result is a consistent improvement in structural crashworthiness (ECE R66) of the bus superstructure.

Customised Curing Times

In addition to ensuring the optimal adhesive properties, Sika’s innovative Curing-by-Design technology introduces a new dimension of flexibility and control over the adhesive curing process. Curing-by-Design introduces a catalyst that delays the curing reaction, decoupling adhesive work time from curing speed and empowering manufacturers to precisely tailor the curing reaction according to their needs. This innovation minimizes unproductive downtime during assembly, leading to rapid curing and faster production processes without the need for external heat sources.

Lighter, Stronger and More Efficient

Thanks to a tailored combination of PowerCure and Curing by-Design technologies, and through extensive collaboration with third-party technology partners 3A Composites Mobility AG (XBODY®), Van Hool and Sika have successfully pioneered a new generation of safe, lightweight, and easy-to-assemble bus roof bonding systems. Compared to previous constructions, the latest model offers enhanced stiffness for all load cases, better stress distribution and a full 500 kg in weight savings, in addition to substantial increases in material efficiency and labour productivity.

Engineering the Future Together

Of course, new designs and assembly processes aren’t born overnight. Which is why Sika is dedicated to supporting your production concepts long beyond the scope of materials and technology. With highly experienced experts in design, process, vehicle, adhesive and system engineering, our aim is to support every customer’s business strategy from prototyping to certification. Ultimately, it’s a people business, where everyone from our adhesive engineers to global and local sales representatives are devoted to pursuing the strategic innovation of our customers.

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Sika Transportation partner services include:

  • Technical documentation to support design and simulation
  • Project-specific surface, material and durability testing
  • Implementation and validation support for the right equipment and efficient processes
  • Tailored customer application trainings
  • Production line audits
  • Individual, localized customer support

Proven performance benefits:

  • Weight reduction
  • Enhanced stiffness for all load cases
  • Improved stress distribution
  • Stable performance properties from -40 °C to 100 °C
  • Additional modules and mixed material design possibilities

Proven production advantages:

  • Less than two hours curing time
  • Fewer workers required for assembly
  • Fewer and faster production steps
  • Easier adhesive application: compressibility, low viscosity, non-sag, no VOC, no odours
  • Suitable for automation processes

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