Ultrasonic welding, perhaps the most rapidly developing field in the industry, uses high-frequency vibrations - not heat - to weld plastic pieces together. Ultrasonic welding machines are used to join small- and medium-sized pieces of plastic by creating frictional heat that melts the plastic together. Once the vibrations stop, the plastic immediately cools and solidifies.

Among the benefits of ultrasonic welding are that it's quick, repeatable and does not use any "consumables," or additional materials. There are no screws, nails, bolts, soldering materials, glues or other adhesives necessary. The finished pieces come out strong and clean - in fact, ultrasonic welding machines can also create hermetic seals. Plus, because no heating is involved, no ventilation system is required.

In this process, plastic is melted into a solid-state weld through high-frequency mechanical vibrations (15 kHz to 40 kHz) and pressure. Many ultrasonic welders run at 15 kHz, 20 kHz, 30 kHz and 40 kHz frequencies.

First, two thermoplastic pieces with similar melting points are placed together, one on top of the other, in the ultrasonic welding machine. Next, the high-frequency vibrations are applied to the joint being welded. Because the application is concentrated in the joint, the heating is enough to melt the joint, but not the base materials. Then, when the plastic melts, the vibration stops, pressure is applied to the joint and the plastics are melded. The process is so efficient and fast, weld times are sometimes less than a second.

The growing number of industries relying on ultrasonic welding machines includes the automotive, cosmetic, computer, domestic appliance, toy, medical, electronics, textile, packaging and food industries. In the medical industry, ultrasonic welding is often used because the process can ensure that no parts are contaminated by outside substances. In fact, products processed with ultrasonic welding machines may be used for "clean rooms" in hospitals. The most common use of ultrasonic welding is in the packaging and food industries where, again, the contaminant-free, clean process is of paramount importance.

Ultrasonic welding has come a long way and is now one of the most progressive industrial techniques. It was in the late 1940s that ultrasonic waves were first used - mostly for cleaning. Then, in the 1950s, ultrasonic welding was introduced as a way to weld plastics and metals. In 1965, the patent for the process was granted to two men - Robert Soloff and Seymour Linsley. The popularity of ultrasonic welding began with the toy industry and has spread to a growing number of applications every year.

Now, ultrasonic welding is the leading assembly method for rigid thermoplastics. Among the models of ultrasonic welding machines are ultrasonic hand guns; bench-top integrated ultrasonic welders; automation ultrasonic actuator heads and modular power supplies; and closed-loop process controls, like energy welding, distance welding, time welding, force welding, automatic frequency tuning and variable-amplitude output control. Plus, there are microprocessor and standard-time models available, and tools of the trade for all makes, models and brands of ultrasonic welders, like ultrasonic horns, fixtures, converters and boosters.

In today's competitive ultrasonic-welding-machine market, it is important to find a plastic assembly solutions provider with top-notch service and technical support, and a company that meets each customer's individual needs. For superior solutions, check out Plastic Assembly Systems at www.heatstaking.com.