High Frequency plastic welding is also called medium fusion. High frequency welding is relying on some property of the plastic, heating plastic products in a rapidly alternating high-frequency electric field. That is placing plastic material with high dissipation factor in the high frequency electric field, heat up and weld the products.

PVC and PU is the most common thermoplastic High Frequency welding material. High frequency welding can also apply on other machine application such as polymers, including nylon (Nylon), EVA, PEVA, PET, PETG, APET and some ABS resin. Nylon (Nylon) and PET require using electric equipment together with warm-frequency welding machine to enable processing.