Engineering a Better Fascia
It is lighter, yet this TPO bumper system gives up nothing in the safety or durability departments. A whole group of people in a $32-million test facility made sure.
The Engineering Test Facility of the Ford Automotive Products Operations in Dearborn, MI, is full of engineers, technicians and scientists who seem dedicated to making and breaking things. How else can you explain, for example, such things as an environmental four-post road simulator wherein full vehicles are positioned in place, and then shaken so that in two weeks on the rig the vehicle has been stressed to a degree that would take 10 years on the road, heated to post-Death Valley temperatures (100°C) and/or cooled to a degree that's not even temperate for Antarctica (-40°C)? Or the pendulum device in the Bumper Technology Group facility, where the bumpers on cars are given a whack (and there happens to be a full vehicle drive through environmental chamber nearby, so the car can be heated or chilled before the drubbing)? Or the "Reliability Useful Life Analysis Lab," where the objective is to take a given component or subsystem beyond its useful life?
All of this activity in the $32-million facility, of course, is to engineer better products for customers of Ford products. And they want to get the job done as quickly as possible. Ford's goal is to reach a cycle time of 19 months. The industry standard is presently 30 months.
One project is the bumper fascia for the 1998 Ford Windstar minivan. It was designed, developed and put through the rigors at the Engineering Test Facility as the result of a cooperative undertaking by Ford Automotive Products Operations (APO), the Windstar Platform team, Montell North America Automotive Business Group (Troy, MI), and Polycon Industries (Guelph, Ontario).
One of the things that Ford is extremely proud of is the fact that the Windstar is the only minivan that scores five stars—the highest mark—on the National Highway Traffic Safety Administration's frontal crash rating. So the development of the new fascia was something that needed to be done while keeping safety in mind, perhaps even more than otherwise might be the case, because those five stars are a distinction that the corporation doesn't want to lose.
Speaking of the new component, Jim Krebs, a product development engineer with Ford APO, says: "This fascia provides significant weight reduction, while improving quality, durability, and maintaining safety standards. It's a major breakthrough for our customers."
Bill Windscheif, marketing manager for the Montell North America Automotive Business Group, notes, "It's not every day that something comes along in the business of bumper fascias that can be considered groundbreaking. Fascias have been modified so often over the decades that one might think there is no more room for innovation or improvement."
But apparently this is the exception.
The fascia is produced with a thermoplastic olefin (TPO) material developed by Montell, HiFax HSBM F762 (the HSBM signifies "high strength bumper material"). The fascia molding is done for Ford by Polycon. The fascias are then shipped to Ford's assembly plant in Oakville, Ontario, where the Windstars are produced.
So what are the improvements? First off, there's the weight reduction that Krebs cites. The new fascia is five pounds lighter than the one it replaces. The key to the weight reduction is the fact that the wall stock thickness required is 2.4 mm rather than 3.5 mm, which is the standard. "It's the material's high flexural modulus that allowed us to reduce wall stock without significantly affecting the apparent stiffness of the part," observes Paul Dellock, Ford Windstar product engineer. The material's flexural modulus is 200,000 psi.
As for the quality that Krebs speaks of, there are several reasons why it is achieved. For one thing, the material has a low coefficient of linear thermal expansion, so there is good dimensional stability. Because it can be molded with 40% less injection pressure than is the norm, there's reduced lifter line read-through. There is good paint adhesion and durability.
From the point of view of processing, there are also benefits. "Reducing wall stock reduces cycle time," explains Paul Dellock. Although none of the involved will say just what the cycle time reduction is, the consensus is that it is "very significant." In addition, because the hold pressure during molding is reduced by 30%, machinery wear is reduced.
There are several environmental factors, too. For one thing, less energy and raw material are required to produce one of the new Windstar fascias. The material can be recycled. And that five-pound weight reduction can contribute to improved fuel economy.
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