Ultrasonic welding machines’ quick, clean process uses high-frequency vibrations and pressure instead of heat to melt and weld plastics, which provides many benefits.

Ultrasonic welding, the preferred choice in plastics welding, is perhaps the most rapidly developing field in the industry. It uses high-frequency vibrations and pressure - not heat - to melt plastic pieces together. By creating frictional heat that melts plastics, these ultrasonic welding machines are used weld small- and medium-sized pieces of plastic. When the vibration stops, the plastic quickly cools and becomes solid again.

In addition to being quick and repeatable, ultrasonic welding machines do not use any additional materials, known as “consumables.” So, no screws, nails, bolts, soldering materials, glues or other adhesives are required. And because finished pieces come out strong and clean, ultrasonic welding machines are also used to create hermetic seals. Another benefit is they require no ventilation system, because no heating is involved.

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.

More and more industries are coming to rely on ultrasonic welding machines. They include the automotive, cosmetic, computer, appliance, toy, medical, electronics, textile, packaging and food industries. Ultrasonic welding is often used in the medical field because the process can ensure that no parts are contaminated by outside substances, which is why products welded with ultrasonic welding machines are able to be used for “clean rooms” in hospitals. The food and packaging industries also favor ultrasonic welding, again because the process is clean and contaminant free.

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.

Today, ultrasonic welding is considered the leading assembly method for rigid thermoplastics. Models of ultrasonic welding machines include: 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. There are microprocessor and standard-time models available, as well as tools of the trade, like ultrasonic horns, fixtures, converters and boosters for all makes, models and brands of ultrasonic welders.

When it comes to companies that provide plastic assembly solutions, look for top-notch service and technical support and a company that meets each customer’s individual needs. For superior ultrasonic welding machines, check out Plastic Assembly Systems at www.heatstaking.com.