World first at Engel Mobility Days 2023

The Engel Mobility Days 2023, the plastics machinery manufacturer’s two-day conference in Linz, Austria - supported by KTM Technologies - were this year centred on the theme of change and sustainability. The programme was both interesting and varied, and included a surprise global premiere: a KTM motorcycle seat base produced using a newly developed tape sandwich process.

Created as a joint project between Engel Austria and Austrian motorcycle, bicycle and sports car manufacturer KTM Technologies, the new seat base combines a greater stiffness, despite a more compact part design and less weight, with low production costs. The mould was supplied by Belgium-based Feronyl, said Hans Lochner, head of Material and Applications at KTM Technologies in Anif, Salzburg, speaking at a press conference held during the Mobility Days.

The need for a more compactly designed seat based was prompted by the ongoing electrification trend, which is impacting not only bicycle and motorcycle OEMs, but also the entire mobility industry.

"We are accommodating increasing numbers of electronic components on the vehicle and need space for them," said Lochner. On a bike, the seat base is one of the most important points of contact, together with the pedals and handlebars. “It’s the closest to the motor, so it needs to be good,” he explained.
Until now, KTM’s motorcycle seat bases have been injection moulded and made from thermoplastic materials. The stiffness needed for the part was achieved by geometric stiffening – through the use of ribs, for example. As a result, the part had relatively high thickness of up to 9 mm. The company was interested in exploring the possibilities of composite materials and production processes to reduce the installation space needed and create more room for electronics. In cooperation with Engel, who contributing expertise in lightweight production technologies and industrialisation, the new tape sandwich technology was developed.
The tape sandwich technology provides an efficient alternative to the conventional injection moulding process in terms of cost and energy; it yields the same stiffness, while requiring much less installation space. Using this technology, the weight of the part could be reduced by a robust 26%.

At the press conference, Franz Füreder, vice president Automotive & Mobility at the Engel headquarters in Schwertberg, Austria, explained the tape sandwich technology, saying: “We work with very thin, single-layer reinforcement materials such as tapes and fabrics with polypropylene matrix, which are inserted into both cavity halves of the injection mould without preheating before the cavity is filled with polypropylene. Due to the specific mechanical properties of the sandwich structure, we can already meet the stiffness required for motorcycle seat bases with a single-layer UD-tape. This means that the tape sandwich process requires significantly less energy and simpler production cell technology than conventional fibre-reinforced plastic composite processing methods. At the same time, the production costs drop.”

Hans Lochner added that not only was the bond achieved using Engel’s technology excellent, less thermoplastic material was needed, which reduced the carbon footprint of the part, and only a minimum of glass fibre was used. The space needed for installation was reduced by 66%.

"The new sandwich structure […] offers maximum stiffness while minimising the number of fibres required," he noted. The sandwich structure also allows for the use of standard thermoplastics, even though the component is exposed to high mechanical stresses, as part performance is now driven by the tape structure. This positively affects the cost, as well.

Promoting sustainability
The partners tested a number of different injection moulding materials in order to asses the global warming potential of the various material combinations. Fossil-based PP was compared with biobased and recycled PP grades, with noteworthy outcomes.
Compared to the series production version – a seat made entirely of fossil PP – the tape sandwich technology, also using fossil-based PP, yielded a reduction in GWP of 27% - a decrease achieved solely through the reduction of the amount of material used. Using polypropylene from renewable sources, the GWP value was 85% lower. In each case, the weight of the component weight was reduced by 26%.
According to Lochner, incorporating recycled material without compromising any mechanical properties is highly feasible. “ We aim to put sustainable materials into the market with clever design,” he said.
In combination with tapes from a PP matrix, parts can be created which can be recycled at the end of their service life. "This new development sees us open up an affordable and sustainable solution for future mobility,” added Füreder.
The partners plan to roll out the technology for use with other parts in the KTM family of motorcycles. As well, the companies realise the potential of the technology for many other lightweight applications in a wide range of mobility disciplines. The two development partners are offering the tape sandwich process jointly, and developing solutions tailored to the specific use case.