High frequency welding is mainly used to produce welded steel pipe. The main principle of high frequency welding (HF welding) is based on di-electric heating of the material to be welded. The objects that needs to be welded are clamped together between two metal electrodes and a high frequency voltage is supplied. As a result the molecyles in the material starts to vibrate and heat up. Eventually the material will melt, and the force supplied by the electrode will melt (fuse) the two surfaces together. After cooling a permanent seam has been created. The resulting weld seam can be as strong - or even stronger - than the surrounding material.
The great advantage of HF welding is the speed of welding: The material is heated from the inside and fuses quickly, within few seconds. Compared to high frequency welding, a lot of other methods (hot air, infrared radiation, laser) the energy heat is supplied from the outside. This means that the heat must first penetrate the material in order to heat the contact-surfaces, thus risking to burn the top layer of the welded material.
What materials can be HF welded?
The material most common in High frequency welding is PVC (sometimes called simply vinyl) and PU (Polyurethane). The material can be thick or thin, reinforced or coated. It can also be plain, coloured or structures. Observe that bonding requires the two materials to flow and mix easily. Thus PVC materials can be welded with PVC components and PUR sheets needs special PUR components.
