Automotive innovation returns: First IM wiper system cuts cost, boosts recycled content

After what appeared to be a dry spell for molded automotive innovations, several new projects point to an upward trend. In this first article of several to follow, collaboration between a Tier One, its molding supplier, and a resin supplier produced a part that goes beyond its initial objective.

Everyone knows you can’t have it all, but try telling that to the team that produced the automotive industry’s first injection molded thermoplastic wiper bracket system, which appears on 2003 models of the Lincoln Town Car. Originally intended to reduce weight, the wiper bracket system, or nosecone, that replaced an SMC version also managed to cut cost and make use of recycled resin.

Located just below the lower windshield edge inside the engine compartment, the nosecone supports and positions the windshield wiper module and provides a seal against the hood. In this capacity, it sees a variety of loads from wiper motor torque along with underhood temperatures. In addition, this part must support the windshield wipers without failing, a critical safety system that most drivers take for granted.

Engineers from Ford Motor Co., Carlisle Engineered Products, Valeo, and DuPont Engineering Polymers collaborated on design and engineering for this project. The overall part design was performed by Carlisle (Chardon, OH) and Valeo, and brought cost savings to the system by eliminating secondary operations; hole drilling, fixtures for drilling, and post-sanding required with the SMC version became history.

DuPont contributed its materials technology and aided in the design effort. According to Chris McBride, senior accounts manager with DuPont, the team chose a 45 percent glass-filled Rynite PET, opting for a recycled material grade. High glass loading boosted structural strength, but rigidity was also designed into the 49-inch-long part so that the long span would maintain its shape under load.

“Structural strength in this part is a combination of materials strength and design techniques,” says McBride. “The wiper system is a safety system, and must perform without fail. A lot of engineering goes into that, such as maintaining the proper wipe angle in bad weather as well as good. Design engineers from DuPont did quite a bit of finite-element analysis work to figure load bearing, and so that they didn’t lose the wipe angle over time. They also determined where to put ribbing to enhance stiffness.”

Switching from SMC enabled the team to configure the part’s shape to meet underhood packaging requirements. Gary Skrypec, Carlisle senior product engineer, explains that the IM process gave designers greater design flexibility within the size envelope Ford specified. In addition, molding the part via injection rather than compression eliminated exposed glass fibers, improving part handling and assembly.

Collaboration was a major reason for the success of this project. Says McBride, “My perspective is that you really have to work together—OEM, materials supplier, molder, and automotive supplier—in order to produce breakthrough applications. These types of departures from the norm are extremely difficult to pull off if all four don’t work together.”