You’ve read our article on Industrial Fabrics Joining Methods and selected hot air welding (which carries several advantages), now it’s time to pick which machine is best for the job. Broadly, there are two types of hot air welding tools: automatic and manual. Automatic tools can be further broken down into moving and stationary.
There are several different joining methods for industrial fabrics including gluing, sewing, chemical welding, and heat welding. The type of project, where it will be used, and the desired lifespan of the final product all affect the choice of method.
Inside every Leister hot air tool is a heating element composed of a ceramic honeycomb supported resistance wire filament (See below). Electric resistance wire heaters work on the principle that when electrical current passes through a conductor heat is generated, and the amount of heat generated is related to the resistance of the conductor.
Some resistance wire heaters are able to function without airflow because they have been designed in such a way that they will not reach temperatures above their safe operating limits. Examples include: a toaster, some ovens, wrap heaters, some space heaters, etc.
However, Leister heaters are designed to operate at very high temperatures—most are designed to heat airflows up to 650°C, and some up to 900°C—and as a result require airflow at all times. To reach these high air temperatures, the heating element must be capable of reaching even higher temperatures. Without adequate airflow, the element will heat up unchecked and will exceed safe limits, leading to the destruction of the element.
Welding vinyl for banners and signs has several advantages over sewing for the same applications.
Heat welding produces a stronger bond than sewing. With the correct application of heat and pressure welds are as strong as the material itself. Conversely, the holes made by the sewing needle weaken the fabric and provide the most likely point of breakage in a final product.
Many sewing threads are not suited for use outside as they deteriorate quickly under the strain of the elements. UV-treated threads tend to be thick and more difficult to work with. Welded seams hold up as well as the rest of the banner or sign.
Sewn seams are more visible than welds, particularly from the front of material. Welds are near invisible improving the finished product’s appearance.
Our previous article covered Finding the Right Welding Parameters for your Industrial Fabric. In brief, the differences between brands, coatings, composition, textures, and environmental factors mean that each material and environment require a different combination of speed, temperature, and air flow to achieve a good weld. When welding a new material, we recommended consulting with the fabric manufacturer to obtain a product data brief. The information in the brief can help minimize the number of test welds needed to find the appropriate welding parameters.
As with all materials, make sure to have numerous, clean samples on hand before beginning testing. Properly fasten each to the table or floor with tape or weights. A consistent plant environment (temperature, humidity, air movement) will produce better results. Make sure that the operator is trained on how to use the welding machine. If you’re using a Leister UNIPLAN, see our article Welding Industrial Fabrics with the UNIPLAN E.
Learn how to install a piping kit, hem kit, guide bar and other accessories on the Leister UNIPLAN.
While Laser IR Thermometers are an extremely common tool, they are entirely ineffective for measuring the outlet temperature of an air heater. To understand why, we must first understand how this tool works. Laser IR Thermometers measure the surface temperature of an object by measuring the thermal energy emitted by the target. Knowing the amount of thermal energy discharged and the emissivity of an object’s surface, the object's temperature can be determined by the device.
When measuring a heater’s output air temperature, the largest issue with these tools is that they measure surface temperatures. As the heated air is transparent, the measurement will always be the surface temperature of a nozzle or a component of the heater housing; and frequently it will be an exterior surface. These items will always be cooler than the heated air, often by a significantly larger margin than the user would expect. To accurately measure the output temperature of an air heater you must measure air temperature and laser IR thermometers are incapable of doing so.
Large format printing of banners can produce a stunning final product. Very large banners require the joining of two or more pieces of material by welding, stitching, or gluing. When welding two banner pieces together the type of ink used becomes an important consideration.
Solvent-based inks cannot be welded. The ink interrupts the bonding process. Instead, leave a margin unprinted on the banner the width of the required weld. Be sure to carefully align the pieces of material to make sure the final product is perfect.
Water-based inks can be welded without issue, no margin need be left when printing.
Have questions about your material? Give us a call.
The new HEMTEK stationary welder from Leister is easy to use, see how in this video:
Have questions? Give your Technical Sales Representative a call for help!