SABIC Innovative Plastics is putting a new spin on the traditional steering wheel with an injection-molded design featuring its Lexan* EXL copolymer resin. At Chinaplas 2010, in booth W2G41, the company is showcasing the benefits of weight out, high performance, manufacturing ease, styling freedom, and parts integration provided by this innovative new steering wheel concept.
Importantly, Lexan EXL resin avoids key environmental drawbacks of existing steering wheels, whose materials can be difficult to recycle and involve potentially hazardous waste products from casting and processing. The company's investment in new technologies provides automotive industry customers with advanced materials solutions for the most demanding applications.
"It's high time for a new direction in steering wheel design, and SABIC Innovative Plastics has made a 180-degree turn with our two-part molded design," said V. Umamaheswaran (UV), director of Products and Marketing, SABIC Innovative Plastics. "Tough new demands on steering wheels - from integration of features to safety and weight-out - require an entirely new approach. We're excited to show Chinaplas attendees this breakthrough injection-molded design featuring our innovative Lexan polycarbonate copolymer resin material, and are confident that the auto steering wheel is entering a new era."
Steering Wheels Overdue for New Material Solutions
Typical steering wheels are comprised of a die-cast magnesium or aluminum armature overmolded with flexible urethane foam. This creates a solid rim section with no package space for integration of electronic components. Additionally, the soft polyurethane makes structural attachment of components impractical. This approach also restricts styling possibilities such as advanced shapes and innovative aesthetics.
In addition to meeting these challenges, updated steering wheel design called for: improved energy management for head and torso impacts; net weight-out even with the addition of integrated components; durability and long service life; avoidance of secondary operations; and overall system cost reductions.
Lexan EXL Copolymer Resin Steering Wheel Cuts Costs and Mass
Lexan EXL glass-filled polycarbonate-siloxane copolymer resin provides excellent stiffness and a high degree of impact over a very wide temperature range. SABIC Innovative Plastics has developed two designs; a two-part injection molded design with a leather wrap as a high-end solution and a one-piece injection-molded armature with a polyurethane overmolding. Both are attached to the steering column with a small metal hub. They have been shown to cut system costs by up to 20 percent and reduce mass by up to 40 percent compared to a magnesium or aluminum alloy steering wheel. Both designs also provide other benefits:
- In the two-piece design, the space created by the hollow rim and spokes enables integration of damping and sensing technology, switch housings, wiring and other functionality inside the steering wheel.
- Injection molding Lexan EXL copolymer resin is a more environmentally responsible process than die-casting magnesium alloy as it reduces carbon dioxide (CO2) emissions dramatically. Compared to die casting 1.1kg of magnesium alloy, which generates nearly 70 kg of carbon dioxide, manufacturing 1.0kg of Lexan EXL copolymer resin only generates 7.6 kg, about one-tenth the emissions.
- Greater design flexibility to create new shapes and ergonomic configurations
- New styling options such as special colors and effects
- Part consolidation through integration of driver airbag attachment and reaction plate, horn mechanism, etc.
- Simpler manufacturing by reducing the number of secondary processes
Overall technical feasibility of the new steering wheel design has been tested. Prototype parts have been built and further OEM validation on vehicles is in progress.