Radio Frequency Welding (RF)

The procedure

RF Welding is a concept in which materials are permanently bonded together using high-frequency electromagnetic energy. That's why it is called HF welding or High-Frequency Welding, also known as RF Welding or Radio-Frequency Welding. The area where this energy is applied to weld together, the materials comes out to be very strong just like the original materials, without any deformation or weakening of internal molecular bonds.

Here the same principle of physics is applied in which two electrodes are used to create oscillating electric fields. When an electromagnetic field is created, the polar molecules orient themselves as per field’s polarity. During this process, heat energy is generated in which can be observed on the material that is exposed to this electromagnetic field. In RF welding there are some limitations and only particular materials can be RF welded. Only those materials that cause heat generation in high-frequency electromagnetic fields are selected for the procedure. The manufacturers are well aware of this factor, and they can quickly select material for the process. There are three parts of HF welding - HF generator, welding machine, and the electrode (Aluminum or Brass dies). All these three things are found in a compact device which does the job in few seconds.

To begin the process the material that needs to be bonded are clamped together between two electrodes. The electrodes are made of Brass or aluminum material. Once the material is firmly placed high electric current is supplied which causes the molecules to oscillate. While applying high frequency, typically between 13 MHz-100 MHz, some of the molecules begin to heat up and ultimately material will melt up. The electrodes play a significant role here by providing appropriate pressure during heating and cooling, to fuse the equipment surface together properly. Unlike other bonding processes where there are chances of burning top layer, HF process ensures safe and stronger bonding, fast execution time and economical also. There are certain quality parameters like electric power supply, pressure intensity, welding time and cooling time that needs to be carefully considered by the manufacturers for achieving optimum results.

Nowadays, there are several materials available which are bonded smartly using the advantage of RF welding Lenticular PVC prints (Polyvinylchloride) and PU (polyurethanes) are the two most popular materials chosen for RF welding process. A typical example of utilization is in tents, tarpaulins, and rafts where eyelets provided for fastening ropes. The other polymers that can be welded using RF weld process are PET, PETG, nylon, EVA and ABS resins. Whatever the thermoplastic material may be, HF welding is capable of sealing material in the better way. Though some materials, need special conditions to execute the process. Materials like nylon and PET need to clamp between preheated welding bars, and then RF power is supplied to complete the process. There is some polyolefin also available in the market that can be RF welded. If you are not aware, do not use materials like polystyrene, polyethylene, polycarbonate, PTFE, etc. for RF welding. You can try other suitable processes like sewing, gluing or applying hot air, etc.

Plain Welding

With the advancement of technology, the plain welding can convert into a welding were decorative features can be obtained on the object. The purpose of welding is same; the only thing is that the welding tool is profiled to give the beautiful appearance of the welded area. Some people also use embossing technique to engrave logos, alphabets, and other decorative embossing effects. Some additional tools are also available for cutting edges that simultaneously cut the material during the welding process. In this technique, the scrap generates, which can separate from the fused material. This process is known as tear-seal welding.

In RF welding process there is a possibility to attach a lenticular piece to the fabric. The part is made out of a polymer that can be firmly RF welded. Sometimes flexible polymer films are used over the piece and between the material and part to bond everything together. The most common material used for making the soft lenticular lens is PVC. Today in the market, readymade lenticular fabric and lenticular PVC sheets are available that can be used to produce a large number of lenticular products. The lenticular flexible polymer sheets provide great strength to the material, and it can last longer. In the ornament designing industry ‘Lenticular Appliqué welding is getting very popular. Here extra content pieces are welded to the surface of a product for making ornamental products.

RF Welding typical applications

Lenticular printing technology has become very popular over the simple printing techniques. With several animation effects, it has completely changed the approach to the advertising industry. Large scale efficient lenticular printers are used for lenticular prints which ultimately lowers the per unit lenticular printing cost. The lenticular sheets provide great looking lenticular print on the desired object.

Here are some typical products manufactured using RF welding techniques:
Card Books, Stationery Wallets, Book Covers, Zip Bags, Check Book Cover, ID Card Holder, Business Card File, 3-Ring Binders, T-Shirts, Credit Card Holder, Coin Purses, etc.

Materials Sealability Chart

(x) = Response of the materials in the 20 to 30 Mc/sec range.