High frequency welding (often abbreviated HF welding or RF welding) is a manufacturing process where two plastic parts are welded together using an electromagnetic field. The resulting join can be very strong – often close to the original strength of the materials joined. In some scenarios the weld can be even stronger than the original materials.
Using a high frequency electromagnetic field, the material is heated and pressure added to melt and fuse the two materials together. No outside heart is applied. Instead the heat is generated within the materials. During cooling (under continued preassure), the materials are fused together and a weld has been created. This results in a very strong bond between the two parts.
Often a High frequency welded eyelet will outlast a traditional metal eyelet 2-3x.
Go deeper: HF-welded vs metal eyelets — why welded wins →
We don’t just explain HF welding — we make the components engineered for it, and the machines that weld them.
Example of High Frequency Welding of PVC Cleat
What are the advantages of High Frequency Welding?
There are many other processes by which PVC components can be bonded to PVC film or other PVC parts. These include ultrasonic welding, friction welding and hot air. Chemical methods are also utilized, PVC bonding adhesive or the chemical cyclohexanone (often used for bonding tubes to flanges).However, High Frequency welding is often the preferred process for the following reasons:
- Rapid welding cycles
- Inexpensive tooling
- Clean process
- No subsequent drying/hardening
Materials compatible with High Frequency Welding
Not all materials can be High Frequency welded together. The most common materials are polyvinylchloride (PVC), and urethane. Other materials such as EVA, PET-G and a number of types of formulations in the PET family are also welded with great success using this method. Additionally, a number of adhesives which are activated by the High Frequency field can be used to weld materials that are not normally considered compatible with this process. An example would be sealing either cardboard to cardboard or thermoformed blisters to cardboard as would be the process in a packaging application.
Common products manufactured with high frequency welding are tarpaulins, tents, ceilings, advertising banners, waterbeds, inflatable boats, medical and especially blod and urine-bags, tensile structures, conveyor belts, rain clothing etc.
High Frequency Welding suppliers
Carmo supplies electrodes for each of our weldable componenents and a series of machines for automatic welding of eyelets. For suppliers of HF generators and barwelders, partners include Forsström and others.
What are the important factors for high frequency welding?
The four most importent factors / process parameters influence High frequency welding are
- Electrical power
- Pressure applied
- Welding time
- Cooling time
Finding the optimal process parameters will depend on your specific equipment, the materials involved and the specific geometries including thichkness and area to be welded. Achieving optimal results is often an experimental process guided by experience. As a guiding rule, the thicker material and focus on short weld times you need, the stronger electrical power / HF generator you need.
High frequency welding machines for plastic components
High Frequency Welding (HF welding) machines are specifically designed to create precise and durable welds in plastic materials. By using high-frequency electromagnetic waves, these machines heat the plastic surfaces to the point of fusion, enabling them to bond seamlessly. This process is ideal for welding thin and thick plastic films, ensuring a strong, clean seam without the need for additional adhesives or mechanical fasteners. With a focus on quality and efficiency, our HF welding machines provide consistent performance, ensuring that your plastic products are securely welded with precision every time.
Some customers have also automated the placement of the foil, giving a fully automated production. More information on Carmo’s machines and electrodes are to be found on the website.
Carmo’s approach to High Frequency Welding
Carmo has developed a four level approach to HF welding, mainly dependent on the customer’s production volumes and requirements for automation.
