Image courtesy of Miller Weldmaster
Erez offers a wide variety of PVC/PU-coated, polyester-based technical textiles that can be used in wide array of applications. These materials stand up to extreme weather conditions, chemicals, abrasion and punctures, as well exhibit high flexibility and UV stability. This makes them ideal for rescue boats, pontoons, ribs, flexible storage tanks suitable for most liquids, berm liners, spill control/protection, and inflatable membranes of all types. Since the textile itself is water proof, the success of these applications relies on the structure’s seams to be reliably leak-proof against liquids and/or gases….and that has everything with the quality of the welds.
Virtually all of thermoplastics exhibit excellent weldability and PVC is no exception. The welding process involves applying sufficient heat to melt the PVC coating, then applying pressure and cooling to form a weld. Welding techniques are mostly differentiated by how the heat is generated and applied. The most common types of thermoplastic welding are Hot Air, Hot Wedge, and High Frequency (radio frequency). They are both suitable for use on PVC-coated textiles. Which one you chose depends on your manufacturing processes and speeds.
Hot Air Welding
Hot Air welders generate the heat required for welding by blowing compressed air across electrical heat elements. The resulting hot air is applied at the welding point thus melting the surface of the thermoplastics. Pressure is applied and a weld to develops as the molecules between the two surfaces intermingle and cool.
Hot air welding is generally used on thermoplastic materials that have a thickness of 1.5 mm (1/16”) or more. Handheld welders are available. Because of this, hot-air welders can construct welds with many different shapes, including curves. It is ideal to use when the weld width needs to change often or when repeated starting and stopping is required throughout the welding process.
Hot Wedge (HW) Welding
Hot wedge welding uses a heated metal wedge precisely positioned at the weld point to provide the required heat. Two sheets of fabric are pulled across the heated wedge, then subject to pressure from rollers. As the melted surfaces intermingle and cool, a weld is formed. These are also available in handheld models. The advantage of Hot Wedge welding is that it can be used to weld very thick materials. Since there is no blowing air involved to create flying dust and dirt, handheld hot wedge welders are often used in field applications were the materials must be welded outdoors on site.
High Frequency Welding
High Frequency welding is also sometimes used to connect PVC-coated textiles, especially in the medical industry. PVC is particularly suited to this type of welding because of its low electric conductivity and polar molecular construction. Heat is generated by rapidly alternating electrical current between two metal plates. The plates apply constant pressure. High Frequency welding has several advantages. Because heat is only generated when the current is on, the welding process is highly controllable. The ability to precisely direct the current means that the process does not heat up surrounding material. This reduces the risk of heat degradation in the material. These assets allow the plate pressure to remain longer making stronger bonds.
Erez Can Help
Erez can help you choose the right PVC-coated textile and welding process for your applications. We also publish a Guide to Welding Thermoplastic Textiles that you can download for free for more information on welding textiles. Contact one of our trained associates to schedule a consultation and see how we can help you develop and improve your products and profitability today.