HOT AIR VS HIGH FREQUENCY HEAT SEALING: WHAT YOU SHOULD KNOW !!

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The assembly of truck tarps most of the time requires several pieces of PVC coated fabric be joined together.

Whether creating large truck tarps, hemming sides, or adding reinforcements or P.V.C. fastening components to be added as such is the case when manufacturing tarps for retractable tarp systems, Side Rolls or Curtain Sides, It is rare that only one piece of fabric is sufficient when creating large truck tarps, hemming sides, adding reinforcements or P.V.C., or fastening components to be added, as is the case when manufacturing tarps for retractable tarp systems, Side Rolls or Curtains.  But how can we ensure that these joints will hold the test in an application as rigorous as trucking? 

In the tarp manufacturing industry, whether for such applications as truck tarps or tarps for industrial buildings, two main types of technologies are used to join fabrics: hot air and high frequency heat sealing. These are two very different technologies which are good to know to better understand their advantages and limitations when purchasing your next truck tarp.

Hot air technology is the most common technique. It is inexpensive, flexible, and simple to operate, and requires relatively light and less costly equipment. The process is as follows: using a device that looks very much like a small compact hair dryer, heated air is blown at about 700 degrees Fahrenheit (370 degrees Celsius) between the two pieces of fabric, and pressure is applied with the help of heat resistant rubber wheels. The heat melts a small layer of vinyl and pressure bonds the two pieces together.

On the other hand, high-frequency heat sealing is a much more sophisticated technology, which requires the use of more expensive equipment and more complex operation. High-frequency heat sealing uses, as its name suggests, a wave frequency that has been specifically granted by the government, ISM frequency, for industrial, scientific and medical. This frequency is 27.14 megahertz.

The heat sealing equipment is equipped with a press of different length and width, depending on the application in which it's being used. This press sends in the two layers of fabric being joined, waves which, for 3 seconds, change polarity 27.14 million times per second. These changes in polarity create friction of the PVC molecules, and completely melt the PVC of the two fabrics. Two pieces of vinyl becomes a single piece.

A joint created by high-frequency heat sealing will be more resistant than that made by hot-air. According to Pierre Bourdeau, President of PTT High-Frequency Heat Sealing Systems, this technology creates joints that are twice as strong thus increasing the life span of your tarp and not having to reweld seams during repairs.

"Tests have been carried out on the materials, with a "pull test" type device, which pulls the fabric up to its shear. These stretching tests, for the most part, were done at the CRIQ. In general, it can be said that heat sealing is twice as resistant to shearing as hot air fusion. In fact, when one tries to break a truck tarp that has been made by heat sealing at high frequency, it is not the seal as such that yields, it is the fabric next to it. The seal is actually stronger than the rest of the truck tarp. "

But heat sealing has its limitations and requirements. Because of the waves used by this advanced technology, materials must be excessively clean. Dirty fabric, fabric which has been exposed to UV rays for too long, or fabric that has been in contact with contaminants or chemicals such as chlorine, can not be assembled by this process. Thus, there is no question of making repairs on a used truck tarp with high frequency heat sealing.

Hot air seams are also more convenient for small additions such as adding layers for reinforcements or hemming sides.

At Alyak 2000, we have opted for these two different techniques of fabric assembly, in order to obtain all the specific advantages of each technique. Thus, large new fabric assemblies are made using a Cosmos-Kabar high-frequency heat sealer, one of the most recognized manufacturers in the world. For repairs and reinforcements, Alyak 2000 relies on the high performance of Leister hot air seaming devices. The best of both worlds!