New York — Medical molders wishing for a clear-on-clear welding solution finally have an answer.
Branson Ultrasonics Corp. has teamed with Sono-Tek Corp., which specializes in ultrasonic spray systems for applying precise, thin film coatings, to use Clearweld additive technology from Gentex Corp. to create Simultaneous Through-Transmission Infrared (STTIr) laser welding technology — capable of meeting medical device manufacturers' challenges for a clear-on-clear, particulate-free, precise weld joint.
The companies introduced the new system at the June MD&M East trade show in New York, demonstrating clear-on-clear welds from the show floor.
Other laser welding techniques such as scan or trace welding require a laser beam to travel along the weld line of a plastic part, heating and cooling as it goes, and require an opaque part to absorb the laser's energy, said Jeffery Frantz, Branson's director of business development. But the medical market is moving away from pigmented parts, he said.
“The beauty of laser welding is that it is the perfect weld,” Frantz said. “It's what every medical molder wants. But clear-on-clear laser welding … it's been a physics problem.”
With STTIr, he said, the Clearweld absorbs the laser energy and localized melt of the substrates produces an almost instant weld with no particulates, no flash and no cure time.
STTIr also shapes multiple stationary laser beams in a wave guide along the entire length of the weld line, rather than following along the line as trace welding does. Because all the lasers fire simultaneously under a clamp force, heating, melting and bonding the component parts along the entire weld line at once, it's also quicker and error-free, Franz said. The customizable wave guide housing the laser ferrules can be configured on multiple axes to accommodate complex, three-dimensional contours.
Though the Clearfield material solved some of the problem of clear-on-clear welding, Franz said, there were still application issues. So Sono-Tek developed a specialized nozzle for spraying fine lines of Clearweld material in repeatable, controllable spray processes, using air shaping to apply a 0.5 millimeters thin, uniform line of coating to the weld area.
The precision application system is also ultrasonic, said Mike Delia, applications engineer at Sono-Tek, making it essentially self-cleaning.
While the system can be used by any medical molder seeking to provide clear-on-clear welding, Frantz said the team is particularly targeting emerging microfluidic devices. STTlr technology is capable of meeting highly specialized manufacturing demands of small, geometrically complex devices and does not use vibration force, making it ideal for delicate parts or those embedded with electronics, he said.
Founded in 1946 and based in Danbury, Conn., Branson is a brand in the industrial automation segment of St. Louis-based Emerson Electric Co. and manufactures plastics joining, ultrasonic metal joining and precision processing equipment, including other laser, infrared, vibration, hot plate and spin welders and thermal processing systems.