Look at the interior trim and dashboard seams in the passenger compartment of a vehicle and it's easy to tell if they really were stitched by a needle pulling thread. In a lower-priced car, the digitally created threads that seemed real from a distance are obviously not when viewed close-up.
Those on the 2010 Ford Taurus' padded door panels and on the dashboard are not mere digital creations, but they are not needle-and-thread either. Telling the difference from the “real thing,” however, is not so obvious.
The seams on the new Taurus not only appear to be stitched when you look close-up but also feel like the real thing when you push on the padded sections and run your fingers over the "stitches." Although they are not needle-and-thread stitches, they enable Ford to give the low/medium-priced Taurus an upscale look and touch at far less cost.
The panels even have the imperfections and slight wrinkle lines in the surfaces that occur when the material over padded panels is actually pulled into position and stitched with needle and thread. And there are slight but obvious differences from one door to another—reflecting the normal variations that would occur, noted Lon Zaback, Ford's Interior Design Manager.
"We didn't try to take out the imperfections," Zaback said. "The slight lumps and bit of waviness give a handcrafted look."
The realistic look was achieved with an innovative multiple-mold process, which begins with a hand-stitched leather model of the section mounted on a dense foam frame. Urethane is poured over the model, producing a flexible mold that carries all the stitching details.
An epoxy is poured over the flexible mold to produce a hard epoxy mold that is immersed in a nickel bath. The epoxy disintegrates, Zaback explained, leaving a hard nickel mold that is used for production. A polyurethane spray is applied to the mold, and when it cures, the result is a flexible panel with an exterior that has the look of leather and with visually stitched, padded convex sections. This process occurs at ambient temperatures, eliminating thermal cycling, so the life of the mold is long.
BASF is the supplier of the polyurethane spray material.
The door-panel sequence continues with assembly in a clamshell tool. The flexible inner panel is placed face down across the bottom of the clamshell and a hard plastic back panel is attached to the top of the clamshell like two slices of bread for a sandwich. A glob of liquid foam (the sandwich "filling") is deposited on the back of the flexible inner panel and the clamshell is closed, causing the foam to spread out and fill all the spaces, particularly the "stitched" convex sections, leaving a small gap around the clamshell perimeter. The cured foam not only produces the padded feel on the "stitched" sections but also bonds the door inner panel and backing panel into a single assembly.
Automotive Components Holdings LLC (Visteon) is the supplier of the panels.
The padded areas in the door and dashboard that result from this process, although soft, are not quite as "push soft" as required for a car seat. Nor does the system currently provide the variations in softness needed for seats. However, Zaback said, an adaptation of the method for seating eventually will come.