Plastic Welding Processes

Ultrasonic plastic welding is the joining or reforming of thermoplastics through the use of heat generated from high-frequency mechanical motion. It is accomplished by converting high-frequency electrical energy into high-frequency mechanical motion. That mechanical motion, along with applied force, creates frictional heat at the plastic components’ mating surfaces (joint area), as a result the plastic material melts and forms a molecular bond between the parts.

This process works through either linear or orbital motion of one part relative to the other. This results in surface friction that leads to heat generation and the formation of a melt layer at the joint. Vibration welding typically has weld times from one to five seconds. Dukane’s vibration welders can handle parts from approximately two inch (50 mm) diameter to six feet (1800 mm) long.

Laser welding is a non-contact joining method that uses a laser beam to melt the plastic in the joint area by delivering a controlled amount of energy to a precise location. Precision in controlling the heat input is based on the ease of adjusting the laser beam size and the range of methods available for positioning the beam. Most thermoplastics can be welded using a proper laser source and appropriate joint design.

This process works through rotational motion of one part relative to the other. This results in surface friction that leads to heat generation and the formation of a melt layer at the joint. Spin welding typically has weld times from one-half to five seconds. Dukane’s spin welders can handle parts from approximately one-half inch (12 mm) diameter using high speed motors up to nine inches (225 mm) diameter using high torque motors.

Another non-contact welding method is infrared welding that uses radiation to transfer heat to the plastic parts. It follows the same fundamental steps as hot plate welding. Two different approaches to infrared welding have emerged. One of the systems uses an electrically heated metal plate which, in some cases, is coated with a ceramic. In the other system, the standard heater plate is replaced with infrared emitters clamped and spring-loaded on either side of a movable platen.

In this process, the facing surfaces of the two parts are heated through conduction, convection and/or radiation from an actual heated platen. The two parts are either pressed against the hot plate, or held next to it for some period of time, then the hot plate is removed and the parts are pressed together to form the weld. Hot Plate welding typically has weld times from ten to twenty seconds. Dukane’s hot plate welders can handle parts from approximately one inch (25 mm) diameter up to five feet (1500 mm) long.

Ultrasonic food processing involves a vibrating knife producing a nearly frictionless surface which does not deform food products and to which they do not stick. The surface cleanly cuts or slits products including fillers such as nuts, raisins, dried fruit or chocolate morsels without displacement or plowing.

Fabric & film processing is the bonding, slitting, or sealing of fabrics and films containing thermoplastic material(s). Typical thermoplastic materials found in fabrics and films include acrylics, nylon, polyester, polyethylene, polypropylene, polyvinylchloride, and urethane. Products from the textile, apparel, nonwovens, packaging, medical and automotive industries all benefit from the fast, clean, and economical fabric & film processing techniques.