Advanced servo drives and immediate performance feedback are among the technologies that keep ultrasonic welding a go-to method for joining thermoplastic parts.
Matchmaking is a unique skill, and in the world of assembly, few people do it better than equipment suppliers. Day after day, these experts use their extensive experience and knowledge to exactly match the right machine to a specific assembly application. When the project involves joining thermoplastic parts, often times the best machine is an ultrasonic welder.
“Manufacturers often come to us and say, ‘Here’s our thermoplastic part, what do you think: Is ultrasonics the best way to weld it?’” asks Jason Barton, director of business development at Dukane. “We tell them that if the required part production volume is very high, and the part is no larger than a shoebox, ultrasonic welding should definitely be considered.”
A few years ago, Dukane helped a medical device manufacturer find the right ultrasonic system to weld three tiny film caps (less than 0.25 inch wide) on polycarbonate disposable sensors. These sensors monitor pH and gas in artificial blood during ex-vivo assessment and evaluation.
Before meeting with Dukane, the manufacturer used a pneumatic ultrasonic welding system that performed somewhat poorly. Average scrap rates were 50 percent, and at times soared to 90 percent. In addition, lack of welding control caused the press thruster to traverse down after the thermoplastic melted. This unnecessary force caused part deflection, inconsistent welding and solidification. It also required vacuum leak testing on each sensor to ensure a hermetic seal.
Barton says that Dukane recommended the old system be replaced with Dukane’s iQ ES servo-based welder featuring Melt-Match technology. A 40-kilohertz unit, the welder precisely controls weld speed during the weld phase and initiates plastic part collapse only when a melt has been detected.
According to Barton, the manufacturer likes the servo-driven system because it repeatably produces a weld that hermetically seals the cap. This allows the company to significantly lessen its product testing time to just 10 percent, while lowering its production costs and improving product quality.
Manufacturers in nonmedical industries also use ultrasonic welding on a wide scale. Automakers ultrasonically join parts ranging from bumper fascias to oil filters, and white goods manufacturers use it to weld windows and light piping to panel displays. On the consumer electronics side, companies regularly ultrasonically weld power packs, phone cases, outlets and light switches.
Although ultrasonic welding has long been the go-to method for permanent assembly of plastic parts, its technology continues to evolve. Today’s advanced machines offer fast, clean, energy-efficient and repeatable welding—as well as unprecedented control over the joining process. These capabilities will ensure ultrasonic welding’s popularity for many years to come.

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