Wednesday, March 27th, 2013
Ask most people what parts of their cars are made of plastics and they will probably name seat cushions, instrument panel, center console, and bumpers. There are more, of course, many of them not visible to the car owner. Their numbers continue to grow.
The lighter weight of plastics is often cited as a reason for the conversion of metal parts to plastics. In vehicles, lighter weight correlates with better fuel economy, but as important as that is, there is more to the story. Performance, design flexibility, eliminating painting and lower cost are other advantages. Somewhat surprisingly, one of plastics’ biggest advantages is only rarely given credit. That would be innovation, and designers and engineers are well aware of it
Plastic materials offer a highly flexible medium for design and the varied production technologies do the same. And so, plastic materials truly are a designer’s medium for innovation. Increasingly then, plastics are the best solution for the combinations
of advantages they offer, and frequently the offer the only practical solution.
For example, Ford Motor Co. designed its EcoBoost engines for the high efficiency and improved gas mileage its customers are asking for. At the same time, Ford engineers also knew that the sound of the engine had to make customers happy. EcoBoost engines use turbo chargers, which usually emit a high-pitched whine that most drivers do not find attractive. That was a problem.
The solution developed by Ford and a team of its suppliers was to tune the sound by using an injection-molded plastic resonator that transforms air passing through it into a new shape, which changes the sound. The next challenge was to get the resonator inside a duct that could fit in the engine compartment.
Metal was considered and tried, but the resonator did not stay put in the duct. Ultimately, the solution was plastic-inside-plastic. The injection-molded resonator is placed inside the mold for the duct, which is then blow-molded around it. Insert-molding is a well established technology. It is used to make plastic fuel tanks, for example. However, doing it requires very specific expertise.
The team of experts that Ford’s Dearborn, MI engineers worked with includes DuPont’s auto industry specialists, Chevron Chemical (Houston, TX), ContiTech AG, part of Continental AG (Hanover, Germany) and Polymer Products LLC (Owosso, MI). Together, they made the resonator in the duct a reality.
About a million of Ford’s EcoBoost engines, each with an insert-molded plastic duct that weighs 20-30 percent less than a steel alternative, will be produced globally through 2013, and ContiTech is looking at a second manufacturing cell in North America.