Principles of High Frequency Welding

High Frequency welding or Radio Frequency welding is a very mature technology that has been around since the 1940s. Two pieces of material are placed on a table press that applies pressure to both surface areas. Dies are used to direct the welding process. When the press comes together, high frequency waves (usually 27.12 Mhz) are passed through the small area between the die or the mould and the table where the weld takes place.
The high frequency or radio frequency field causes the molecules in certain materials to oscillate and get hot up to the melting point of the material. The combination of this heat under pressure causes the weld to take the shape of the die. HF welding is fast.
High Frequency welding is used in a variety of industries where a strong consistent leak-proof seal is required. HF welding can only be used with materials of which the molecules allow themselves to vibrate due to the alternating electrical field, therefore PVC (polyvinylchloride) and PU (polyurethane) are the most common thermoplastics to be welded with HF. It is also possible to weld other polymers such as nylon, PET, EVA and some ABS plastics.
The great advantage of HF welding is its speed. Because the material is heated from the inside out, the fusion takes place very quickly, often already within a few seconds.
The welding tool can be engraved to give a personal or decorative aspect to the product. A cutting edge can be added next to the welding area, allowing the machine to perform simultaneous cutting and welding operations and to evacuate thereafter the scrap part of the fabric.