Critical to making the new construction work was identifying adhesive and cure properties that met the automakers’ performance requirements for durability, he said.
“It really came down to balancing some of the cure properties of the adhesive itself, its elastic properties, its bond strength and also the stiffness of it,” Billotto said.
The partners ended up with a bond that provides rigidity and strength to the liftgate’s joints, Asthana said. DuPont’s Betaseal structural adhesive systems were customized for use on low-surface energy substrates and generally cure faster.
There also is a consideration in their concept for how the resulting liftgate will look. “We have a very clean look around the joints,” Asthana said of the first two applications.
“In addition to the aesthetics, we obviously want a water-tight seal so there is no water ingress during the lifetime of liftgate,” he added. “The adhesive is not just a bonding feature, but also a sealing feature.”
The bonding approach also represents an efficiency gain on the manufacturing side.
“There’s flexibility built into the adhesive formulation to enable quick curing speed at room temperature,” Billotto said. “But we also have the flexibility to work with external heating sources to accelerate the cure in key areas, to give initial and quick holding ability to the assembled parts.”
That’s important from a manufacturing perspective, he said, because it determines how many fixtures and tools are required on an assembly line to meet production rates.