Orlando, Fla. — Herrmann Ultrasonics Inc. of Bartlett, Ill., is making it easier to add plastic trim in cars, demonstrating ultrasonic compressive staking of dissimilar materials during NPE2018.
The auto industry, in particular, could use ultrasonic applications in door panels as well as for interior trim on the A, B and C pillars — or the front, center and rear pillars — along with on cup holders and instrument panels, Chuck Hannah, ultrasonic engineering manager in the plastics division, said in an interview at NPE2018 in Orlando, May 7-11.
"Temperature does not affect the ultrasonic tool," he said, and the process allows faster production of parts, higher bonding strength and more process repeatability.
Staking may take 1.6 seconds plus a 1-second holding time vs. 10-20 seconds for thermal staking. Those times exclude recommended warm-up and cooling cycles.
The compressive staking process uses a hollow rivet with a tubular shape and a variable bore depth that is adapted and customized into a form-fitting bead for each particular application. That sequence eliminates budding of the rivet.
The vibrating sonotrode never touches the staked upper part and avoids inflicting damage.
Ultrasonic compressive staking is viewed as applicable to a range of materials and enables bonding between new material combinations including metal-plastic hybrids, thermoplastic resins, thermoset plastics and multicomponent systems.
Parent firm Herrmann Ultraschalltechnik GmbH & Co. KG of Karlsbad, Germany, obtained a German patent for compression staking in 2011 and a U.S. patent in 2018, and it also holds a patent in China.
Herrmann Ultraschalltechnik and mechanical engineering professor Michael Gehde of Chemnitz University of Technology began exploring the benefits of compressive staking in 2012.