What is radio frequency welding and why it is different from other techniques

Radiofrequency welding, also called high frequency welding (HF), is a technique of great reliability and effectiveness applied to the production of medical bags, and consists in the safe and durable joining of materials.

This technique is substantiated by the simultaneous application of pressure and an electromagnetic field, which through a certain frequency falling within those allowed by current legislation (27.12 MHz; 13.56 MHz; 40.68 MHz), operates on the molecules of plastic materials, in such a way as to make them weldable at temperatures considered to be relatively modest.


This type of welding is carried out through a system consisting of: a high-frequency generator, a pneumatic press, an electrode with the task of transferring the radio frequency current to the material to be welded, and a metal plane for welding, also used for the positioning of materials.

The result obtained at the end of the process, affects 4 factors: pressure, the effect of welding, time and cooling mode; these parameters can be adjusted in such a way as to obtain the optimal combination according to the material you want to weld.

Another fundamental element that affects the success of this technology, on which the different parameters obviously depend, is the material, which must have a certain dielectric property. Not all materials, therefore, can be welded with this technique.

For example, Polycarbonate, Polyethylene, Polystyrene, Polypropylene and PTFE; are not used, because the high frequency voltage, must lead to the inner heating of the material, regardless of the increase in the outside temperature, thus causing the fusion and the rapid and definitive integration of the different materials, and clearly does not lend itself to the above-mentioned compositions.

PVC and PU, on the other hand, are the most used, while the varieties of nylon, PA, ABS, PETG, even if they could be chosen, could involve a worsening of the working parameters.

Radiofrequency welding differs from other welding techniques, also because it does not generate fumes and the use of additives harmful to health is not required, thus protecting the operator and the environment.

We can say in conclusion therefore, that this welding technique is strongly recommended for very short times, and also thanks to the fact that it allows you to avoid burning the welded material during the process, as this method does not require heat from the outside, but the material is heated inside, and this aspect differs radically from other methodologies.

From a functional point of view, the performance of radio frequency welded bags is on average more satisfactory and constant than those obtained with different techniques.

In 1985 Infra implemented within its production process the first plant for radio frequency welding. Today there are 6 plants for radio frequency welding and 1 for traditional thermal welding.