What Is High Frequency Welding

       

High frequency welding, otherwise known as dielectric or radio frequency welding, is a process used to bind plastics. High frequency welding falls under several other umbrella terms, such as heat sealing and plastic welding.

Materials

Many of the common materials that can have an RF weld are plastics that contain chemical dipoles.Materials such as polyvinylchloride (commonly called PVC,) polyamides and acetates, are all receptive to the electromagnetic waves used for high frequency welding. PVC and polyurethanes are some of the most common materials for this sort of heat sealing.

Other polymers can be welded in this manner, such as nylon, EVA, PET and certain ABS resins so long as they're treated properly. PET and nylon are capable of hf welding if preheated welding bars are used along with the radio frequency energy.

Process

High frequency welding relies on manipulating specific properties of a material. By utilizing a high frequency (13-100 MHz) electromagnetic field, hf welding generates the heat necessary for a heat seal bond. The area to be welded is pressed between two metal bars which act as both the conduits for the energy field and the pressure applicators for heating and cooling. When the frequency is applied it causes the molecules of polar thermoplastics, such as PVC, to spin. The molecules spin fast enough to generate a strong heat which makes the material malleable and capable of being altered to the shape of the die (the metal bars in this case.) The pressure keeps the surfaces tightly together so that when the high frequency is turned off and it cools it makes a leak proof weld.

An RF weld (yet another name for high frequency welding) is very fast and quite consistent in producing a strong leak proof seal. This makes it quite popular for a variety of industries needing a proper heat seal when using the right materials for bonding.

Uses

HF welding is predominantly used to joint multiple layers of sheet material, although there are a number of other uses.

By altering the shape of the die, the weld can become a decorative effect as the material conforms to the shape of the die as it melts. For this reason it can also be used as a form of embossing to place letters and logos on welded materials. An RF weld can even be used to apply extra pieces of material to the surface of the product for ornamental effect.

If a cutting edge is used next to the welding surface the process can double as a means to cut the material. Because the cutting edge makes the material thin enough for excess to be torn off, it is often referred to as tear-seal welding.