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What is high frequency welding?


High Frequency Welding, referred to as Radio Frequency (RF) or Dielectric welding, is the procedure of fusing materials together by applying radio frequency energy to the location to be joined.


The procedure involves subjecting the components to be joined to a high frequency (frequently 27.12 MHz) electromagnetic field, which is generally applied between 2 metal bars. These bars also function as pressure applicators during heating & cooling.


The vibrant electrical field triggers the molecules in polar thermoplastics to oscillate. Depending on their geometry and dipole moment, these molecules might convert several of this oscillatory activity into thermal energy as well as cause heating of the product. A step of this communication is the loss variable, which is temperature and regularity reliant.


Polyvinylchloride (PVC) and also polyurethanes are the most typical thermoplastics to be welded by the RF process. It is feasible to RF weld other polymers consisting of nylon, PET, PET-G, A-PET, EVA and some ABS resins, yet special problems are called for, for instance nylon and PET are weldable if preheated welding bars are used in addition to the RF power.


High frequency welding is normally not ideal for PTFE, polycarbonate, polyethylene, polypropylene or polystyrene. Nevertheless, as a result of the upcoming constraints in the use of PVC, an unique quality of polyolefin has actually been developed which does have the ability to be HF welded.


The main function of high frequency welding is to create a joint in 2 or more thicknesses of sheet product. A variety of optional attributes exist. The welding tool can be inscribed or profiled to provide the entire bonded location an ornamental appearance or it can integrate an embossing technique to put lettering, logo designs or decorative results on the welded things. By including a reducing edge adjacent to the welding surface area, the procedure can all at once cut a material and bond. The cutting edge compresses the warm plastic adequately to allow the excess scrap material to be torn off, therefore this process is frequently described as tear-seal welding.


A common plastic welder contains a high frequency generator (which develops the superhigh frequency current), a pneumatic press, an electrode that transfers the radio frequency current to the product that is being bonded and also a welding bench that holds the product in place. The maker might additionally have a grounding bar that is typically placed behind the electrode, which leads the current back to the equipment (grounding point). There are various sorts of plastic welders, the most usual being tarpaulin machines, product packaging machines and automated machines.


When welding, the device is bordered by a radio frequency field that, if also solid, can warm up the body somewhat. The stamina of the radio frequency field additionally depends on the type of device being used.


When defining radio frequency magnetic fields, the field's regularity is frequently pointed out. The permitted regularities for plastic welders are 13.56, 27.12, or 40.68 megahertz (MHz). One of the most popular industrial frequency for HF welding is 27.12 MHz.


The radio frequency fields from a plastic welder expanded around the equipment, yet most often it is only ideal alongside the maker that the area is so solid that preventative measures need to be taken. The field's stamina lowers sharply with range from the resource.


The toughness of the field is given up two various measurements: the electric area toughness is determined in volts per metre (V/m), as well as the magnetic field strength is gauged in amperes per metre (A/m). Both of these need to be determined to get an idea of exactly how strong the radio frequency area is. The present that goes through you if you touch the equipment (contact existing) as well as the present that undergoes the body when welding (generated present) must likewise be measured.


Optimum permitted degrees according to EU guidelines:


Typical over 6 mins

Electric field stamina: 61 V/m

Magnetic field strength: 0.16 A/m

Induced present: 100 mA

Contact existing (not balanced): 40 mA