Indispensable in the field of vinyl fabric technologies, Radio Frequency (RF) or High Frequency (HF) Welding is a method by which two materials are adhered using electronic currents. This versatile and simple process is used on many engineered textile products, from simple seam and patch attachment to complete item manufacturing.
The Process
Radio frequency sealing occurs when an alternating current crosses between two plates, usually through a bar or a metal die, and through heat and pressure bonds two materials together. PVC compounds contain polar molecules, or molecules with magnetic poles. These types of molecules are easily excited by RF energy, very similar to water molecules in items placed in a microwave. As the molecules move more and more, heat is created which melts the materials – when this process is combined with shaped dies or bars and pressure, materials are bonded to an extent that creates a stronger material than either base material used to create the product.
Stationary Radio Frequency Welding uses a machine with a moving top plate for ease of material and die placement. The basic operation of high frequency sealing is:
1) Electricity enters the machine at 220 volts (alternating current – A/C). Most of this power goes toward powering the dials, lights, and controls.
2) Energy flows into the step-up transformer, which increases the 220 volts to 7,500 volts.
3) Current then flows to the rectifier tube, which changes the A/C to direct current (D/C).
4) The current flows to the oscillator tube, creating radio frequencies by taking the D/C and changing it back and forth between electrostatic charge and magnetic field. This oscillation changes the current to A/C with a frequency proportional to how often the current changes states.
5) The radio frequency radiation travels to the top plate when the machine’s sealing cycle is activated. The radiation will complete the circuit through the die and material to be sealed.
6) The RF flows from the top plate, through the die, to the bottom plate. The circuit is completed as the bottom plate feeds the current back through to the rectifier tube.
Why Use High Frequency Welding
Seals created in HF/RF sealing are more complete than hot air or sewn seams. With hot air, there is still heat and pressure but due to the delivery system the outer layers tend to be the only part of the materials that melt. When tension is placed on these types of seams the individual layers of the material may separate and cause the seal to fail. An RF weld causes all parts of the material to heat and melt, due to the heat being derived from the molecules’ movement. Sewn seams carry with them any problems associated with sew lines, including the holes in the material caused by the process, the added chance of failure due to thread breaking or exposure, and the difficulty of sewing various shapes which may be more problematic due to the seam location on a product.
Ubiquitous!
High Frequency Welding is used on most of our products – it’s used to attach patches and items to our heavy duty canopies, to attach cathedral windows in tent sidewalls, and create smaller components used on our Humanitarian and Military shelters. It’s also the primary construction method for our Disinfecting Mats; the water-proof seal keeps all contaminates within as opposed to sewn mats, which are perforated from the sewing process. With just a few different shapes of dies and bars, fabric material sealing has allowed our designs and products to advance by leaps and bounds.
For more information on our processes, materials, and products and contract RF Welding, visit our websites:
www.gettent.com – our main product hub for all available commercial event ant tent items for sale
www.celinaindustries.com – information on all of our manufacturing capabilities. We would be happy to quote contract fabric welding work. Call us today at 1-888-324-0654 or email us at sales@celinaindustries.com.