5, 1998 Design News
Polymer fender flares are tough
by Karen Auguston Field
One of the unique aspects of polyurethanes is their
elastomeric properties. As a consequence, materials
like SPECTRIM BP 80, a polyurea composite polymer from
Dow Automotive (Midland, MI), are finding their way
into automotive applications such as body panels where
high impact resistance is required.
As an example, the material is being used in fender
flares on the new Ford F-350 dual rear wheel trucks.
"If the body panel isn't tough enough with good
paint adhesion, the impact can create a mesh of cracks
in the panel and chips in the painted surface,"
says Randy Scott, Dow's marketing manager for body panels.
But after a simulated 150,000-mile durability test driving
rough desert roads in Arizona, the polymer panels resisted
abrasions and stone pecking.
Weighing in at 15 lbs the molded components are 30%
lighter than the sheet molding compound (SMC) fenders
they replaced. And Ford's development costs were also
lower, primarily because the polymer can be molded at
lower pressures than SMC. That means the prototype tools
could be made of epoxy, which are less than half the
cost of metal or spray metal tools.
For consumers, the payoff is a tough truck that looks
great from the start, and continues to look great after
miles of rough roads.