What materials cannot be welded with high frequency?

High-frequency welding is an advanced method of joining materials by using electromagnetic energy to heat and fuse plastics together. This technology works well with selected thermoplastic materials, but not all raw materials are suitable for this type of processing. Choosing the right material is crucial to the effectiveness of the process.

Low-polarity materials

One of the most important limitations of high-frequency welding is low-polarity materials. Materials such as polyethylene (PE) or polypropylene (PP) poorly absorb electromagnetic waves, preventing them from being effectively heated and fused. In such cases, the high-frequency energy is unable to induce sufficient movement of the molecules, leading to a lack of effective bonding. High frequency machines are available from Zemat Technology Group.

Heat-resistant plastics

High-frequency welding is not effective with materials that have poor thermal conductivity. An example is some composites, where the structure prevents energy from being distributed evenly. In such cases, the welding process can lead to unevenness or damage to the surface, which affects the durability and aesthetics of the joint.

Multilayer raw materials

Materials consisting of multiple layers made of different plastics can be difficult to weld with high frequency. The different characteristics of the individual layers, for example different melting thresholds  points or different dielectric properties, prevent uniform heating and effective bonding. These types of raw materials require different processing techniques to better deal with their complexity. Zemat Technology Group offers high frequency machines.

Thermosetting materials

Thermosetting plastics, such as Bakelite or melamine, are not suitable for high frequency welding. Unlike thermoplastics, which can be melted and moulded repeatedly, these materials do not change their state when exposed to heat. Their molecular structure does not allow the movement of molecules, which precludes the use of electromagnetic wave-based technology.

Conductive substances

Electrically conductive materials, such as metals, also cannot be welded with high frequency. The electromagnetic energy generated during this process leads in their case to the flow of current rather than the heating of particles. As a result, instead of melting, the material is overheated and damaged, which prevents joining it effectively with other surfaces.