Application: Sensor holder in car bumper
Reliable results
without a trace
Holders for the sensors of car parking assist systems are welded to fully
paint-coated thin-walled bumpers. The weld must be completely invisible from
the outside. Nevertheless, the weld has to be firm, reliable and durable. A
first-tier supplier has opted for the SONIQTWIST® torsional ultrasonic welding
system made by the Swiss TELSONIC AG and is achieving top results. With this
system it is even possible to reduce the bumper thickness by 20%. The OEM is so
pleased with the system that he has now released it for other brands.
"When the
sensor holders are welded to the fully paint-coated bumpers, the weld must be
completely invisible from the outside", explains Wolfgang Ott, Head of the
Plastic Welding Department at TELSONIC. Nevertheless it is imperative that the
process of connecting the plastic clip to the bumper is absolutely reliable.
After all, the clip has to hold the sensors for the distance control and
parking assist system. In the same way, the retractable headlight cleaning
system has to be attached to the car body beneath the Xenon headlights.
Fully
automatic, firm and reliable
The world's
third-largest bumper manufacturer relies on the SONIQTWIST® torsional
ultrasonic welding process made by TELSONIC AG, Switzerland. The system
achieves strong welds that easily and reliably comply with the 250 to 300
Newton strength requirement without the sonotrode penetrating into the bumpers'
substrate. The reliable connection process relies entirely on boundary friction
between the holder and the bumper. The process does not produce any visible
blemishes or marks on the exposed side of the bumper.
In previous
trials with welding processes by other suppliers some deformations were caused
by the sonotrode and the values for strength varied a great deal. In some cases
the bumper was punched through. Alternative bonding processes showed weaknesses
when exposed to temperature fluctuations with extremes of heat or cold. Some
sensors even dropped off thus disabling the system. The result was that bumpers
got damaged.
But not so
with the SONIQTWIST® torsional jointing technology. Ultrasonic heads with a 1.2
-2.4 kW rating, fitted to a fully automatic bespoke system or a robot with
several actuator units, weld the sensor holders to the pre-punched recesses in
the paint-coated bumpers in a reliable process with full repeat accuracy. The
cycle time required for the welding process is not more than about
200 - 300 ms. A German car manufacturer has successfully
introduced the fully automatic jointing process, which is suitable for serial
production, for the models of its premium brand and has now released it for
other brands.
Reducing
weight and costs
A welcome side
effect of the process has become extremely important for the OEM: because
SONIQTWIST® works with boundary friction and does not leave any marks on the
outside, the thickness of the bumper could be reduced. For this ultrasonic
welding process developed by TELSONIC, the thickness of the material can be
between 2.5 and 3.0 mm. Compared to the previous thickness of 3.4 mm and over,
considerable savings and, importantly, a significant weight reduction can be
achieved, which in turn can reduce the CO2 emissions. In this way SONIQTWIST®
helps manufacturers to comply with the respective EU standards.