Italy’s Sole SpA uses the Dolphin process for the cockpit of the Mercedes-Benz Acros truck. (Daimler AG photo)
ODERZO, ITALY (Nov. 14) — In June 2011, Daimler AG’s Mercedes-Benz business launched the latest version of its Actros truck, which it said was “developed from scratch,” with a new interior design including a soft-touch cockpit.
The cockpit is injection molded using the Dolphin process, which combines foamed-in-place technology with two-component hard/soft molding. It is produced in a plant in W"rth, Germany, located on Daimler premises but operated by Italian automotive molding company Sole SpA.
Sole makes cockpit parts using Engel Coinmelt decompression technology. Dolphin was developed by Engel with Swiss mold maker Georg Kaufmann and materials suppliers BASF AG and P Group (now So.F.Ter) in 2007, based on the use of BASF’s Ultradur polybutylene terephthalate for the primary rigid component and thermoplastic elastomer from P Group.
But Sole business-development director Giuseppe Maiarellei told European Plastics News at the company’s headquarters in Oderzo, where the cockpit was displayed in its showroom, that the material solution has now changed from the original concept.
So.F.Ter supplies Pibiflex 3567 S (a TPE block copolymer from crystalline PBT and amorphous polyether glycol), and the rigid component material, a mineral-filled PC/ABS blend called Reblend.
The Dolphin process was first evaluated in 2007 by automotive supplier IAC for part of a Scania truck dashboard, and the process was shown by Engel and its Dolphin partners at K2007 in cooperation with Johnson Controls Inc. But the Actros cockpit is believed to be the first Dolphin application in serial production.
So.F.Ter said the Actros dashboard is made up of four panels extending across its entire width, including a lower part with foldaway drawers.
As with the original concept, the soft TPE secondary component is foamed using Trexel’s MuCell microcellular foaming process.
Dolphin consortium partners are talking of the potential to also physically foam the rigid component to save more weight than already achieved with the TPE surface. There should also be the possibility of using Pibiflex TPE for airbag cladding, where it maintains breakthrough performance over a wide range of temperatures, according to So.F.Ter.
Mathias Dettinger of Daimler’s interior and system evaluation department in Stuttgart said trucks and cars have been shifting toward very similar interior designs. High-quality appearance and feel of cockpits are now equally important in both sectors and are appreciated by truck drivers, who use their cabins around-the-clock as working, living and sleeping spaces.
The preceding design of the Actros 2 truck in 2002 considerably narrowed the design gap with cars; the 2011 design even more so, and this helped the new Actros win the Truck of the Year 2012 award. Mercedes-Benz offers the truck with a cockpit in two widths and three equipment lines.
Dettinger compared the cockpit made with the Dolphin process with those made with conventional back-foamed foil and cladding with foamed foils. He noted that foil thermoforming and cladding processes can cause differences in surface appearance and require wider part tolerances, leading to uneven gap dimensions.
Dettinger concluded that the other processes “are not forward-looking technologies.”
He said Dolphin, on the other hand, can achieve closer tolerances and should cost less over the product life cycle, despite “very complex and expensive tooling.”
Even if parts are designed with many reinforcement ribs in the rigid primary component, any consequent sink marks on the top surface are hidden by the foamed TPE. Integrated clips and snap fittings can be produced without sliders and designed in the same full thickness as the rest of the part, instead of being joined by a narrow section as would be needed with conventional injection molded polypropylene parts.
That aspect was well-illustrated during an Engel Symposium open house in Austria in June, where the Dolphin process was demonstrated live.
When the new Actros application was announced in December 2011, other series applications for Dolphin were said to be under discussion. At the Engel Symposium in June, a demonstration example was displayed of a Hyundai Mobis car dashboard made with the Dolphin process, showing its applicability in cars as well as trucks.