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High driving safety through extreme break resistance coupled with 3D styling

Published on 2009-06-11. Author : SpecialChem

Leverkusen -- Safety is paramount in the rugged world of forest operations. Drivers of forestry vehicles must be protected against falling branches through break-proof windows. A good all-round view further contributes to their safety. John Deere, a leading global manufacturer of forestry equipment, has moved to achieve these two requirements with polycarbonate glazing solutions from Bayer MaterialScience in the drivers' cabs of its new E-Series of vehicles for felling timber.

he drivers?cabs of harvesters and forwarders of the new E-Series of John Deere are fitted with a total of five large panels made of solid sheets of polycarbonate glazing of Makrolon? GP 099

The cabs of the harvesters and forwarders are fitted with a total of five large panels made of solid sheets of polycarbonate glazing of Makrolon® GP 099 grade from Bayer Sheet Europe GmbH. This glazing is used in automotive applications because of its design flexibility and the potential it offers for function integration and weight reduction, but it was the extremely demanding requirements for driver safety that led to the polycarbonate being chosen for the cab windows. In addition, rather than being flat as in previous cabs, the sheets were curved for a more attractive design and to provide a better all-round view.

"Due to these design and safety requirements, we were looking for a polycarbonate manufacturer with a great deal of expertise in vehicle glazing. We decided on a co-operation with Bayer MaterialScience because the company offers comprehensive know-how in every stage of the sheet manufacturing process and beyond - from design and thermoforming to scratch-resistant coating and bonding," explains Sven Künstler, Project Manager E-Cab at the John Deere plant in Bruchsal, Germany. This comprehensive expertise is part of BayVision®, the competence brand for polycarbonate vehicle glazing of Bayer MaterialScience.

Thanks to their high impact resistance and strength, the solid, 12-millimeter-thick polycarbonate sheets prevent falling objects such as thick branches, stones or broken wire cables from winches penetrating the cab and injuring the driver. In doing so, they comply with a set of requirements that are among the strictest in the field of vehicle occupant protection. For example, they easily pass the FOPS test (falling-object protective structures) laid down in ISO 8083. This test involves a long cylindrical steel object being dropped on the sheets with an impact energy of 5,800 or 11,600 joules, depending on whether the sheets have been fitted in the vehicle horizontally or vertically.

They also pass the OPS test (operator protective structures) described under ISO 8084. This tests the static load resistance of the sheets using a force of 17,800 Newtons. In contrast to glass and laminated glass, the polycarbonate sheets do not splinter and break when subjected to loads. This not only maximizes safety, it also increases the lifespan of the sheets - and, as they need to be replaced less frequently, this in turn reduces downtime.

Crystal clear for optimum vision

As the cab of the new E-Series models rotates freely, the driver can gain a 360-degree view of his work environment without having to turn his head or his seat. The large polycarbonate sheets also play their part in ensuring that the driver has a clear view of what's going on. The sheet for the front window, for example, is 1,576 millimeters long and up to 1,128 millimeters wide. Despite their thickness, the optical quality of the sheets is excellent.

"Our task was to extrude the sheets in such a way that there were no inclusions or streaks that could impede the driver's vision or strain his eyes. That meant the distortion of the sheets also had to be reduced to a maximum of 0.06 diopters," explains Thorsten Jung, Segment Manager Industry & Communication at Bayer Sheet Europe.

At KRD Sicherheitstechnik GmbH, the sheets are formed, coated and trimmed, and an adhesive primer is applied to the edges. "Forming these unusually large, thick sheets was a real challenge. By refining one of our own special thermoforming processes, we were able to ensure the sheets achieved a high optical quality comparable with that of automotive glass while also ensuring safe handling of the sheets, even in large quantities," says Corinna Brammer, Managing Director of the Geesthacht-based company. The sheets are given a hard coat based on the polysiloxane topcoat Momentive AS 4000 from Momentive Performance Materials GmbH in Leverkusen. This gives the sheets scratch- and weather-resistant properties very similar to those of glass.

BayVision® - customized service for automotive glazing

Bayer MaterialScience has identified a trend towards 3D styled polycarbonate glazing in a diverse range of commercial vehicles. The company provides OEMs and system suppliers with a comprehensive package of know-how and services covering all the stages involved in implementing these glazing components - from selecting materials, 3D design and mold design to proving of large molds. These services are part of BayVision®, the brand that brings together the company's expertise in polycarbonate vehicle glazing and a range that includes Makrolon® polycarbonate, used in the drivers' cabs of the new E-Series of forestry vehicles from John Deere.

About Bayer MaterialScience

With 2008 sales of EUR 9.7 billion, Bayer MaterialScience is among the world's largest polymer companies. Business activities are focused on the manufacture of high-tech polymer materials and the development of innovative solutions for products used in many areas of daily life. The main segments served are the automotive, electrical and electronics, construction and the sports and leisure industries. At the end of 2008, Bayer MaterialScience had 30 production sites and employed approximately 15,100 people around the globe. Bayer MaterialScience is a Bayer Group company.

Source: Bayer MaterialScience


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