Many people may be familiar with the phrase “RF Welding” but are unsure as to what it really means. RF (radio frequency) welding, also known as HF or high-frequency welding, refers to the process of bonding materials together through the use of electromagnetic energy. This process creates an oscillating electric field that shifts and moves polar molecules within the materials between a tool and the platen. When these molecules move, they release energy in the form of heat. When enough of this energy is applied, the molecules begin to melt and bond to one another. The weld is completed by applying pressure to the bonded area, ensuring a successful seal without any external heat.
What Factors Influence a Good Weld?
There are many factors that affect the strength and quality of a seal in RF welding. Some of the most important factors in creating a good seal include tooling layout, weld thickness, and machine control. All RF welds require adjustments in the power level, pressure level, and time for both weld and cooling settings. The best RF weld results from machines that control the power, pressure, and time precisely throughout the welding cycle. The appeal of RF welding lies in the completeness of the weld that it provides. When you choose RF welding as your method, you can create very robust hermetic seals. These seals are airtight, as many welds are subject to peel tests, leak tests, and optical tests to determine whether or not the correct conditions have been achieved.
What Materials Can Be Welded?
Here is a list of the most common materials the RF welding is performed on:
- Thermoplastic Polyurethanes
- Open Celled Polyurethanes
Is RF the same as Heat Sealing?
While many people, including some RF machine manufacturers, refer to their RF machines as “Heat Sealers”, the term is inaccurate when explaining RF technology. Heat sealing is the process of sealing one thermoplastic to another similar thermoplastic using heat and pressure. The direct contact method of heat sealing utilizes a constantly heated die or sealing bar to apply heat to a specific contact area or path to seal or weld the thermoplastics together. While RF does involve the heating up of molecules within materials, there is no external heat source applied topically to the material. In fact, the RF tool is usually regulated to maintain the same temperature as the ambient temperature or just slightly warmer to produce the most efficient RF weld.
History of RF Welding for Plastic Materials
RF (HF) welding can also be referred to as dielectric welding, and is a relatively mature technology with regard to welding plastics. It has been around for over 50 years, starting in Europe, as a result of theoretical knowledge of the first radar systems and post-war experience accrued in the field of inductive and capacitive heating of materials. Today there are only a handful of manufacturers based in the U.S., with JTE leading the way in providing advanced controls for all of its RF machines, with a specialization in automation and conversion of existing sewing operations.
If your machine is not as efficient as you would like, your welder may not be the right machine for the job. Our eBook 5 Signs That You May Be Using the Wrong Fabric Welder can help you figure out the answer to this question, and help you find the machine that fits your welding needs.