Welding vs. Gluing
Why is welding better for inflatable manufacture than gluing?
Thermo set plastics have a dry abrasion quality that makes them wear better when dry. A good example of this is Neoprene belting for the mining industry. In the water they are at a disadvantage because these materials grab on rocks and are prone to wear faster because they are not as slick in the water. Thermo plastic coated fabrics are weldable because the coatings can be melted and fused together. This means that heat of friction can also melt the coatings, and the consumer needs to be aware of this. However, in a water environment, heat of friction is not an issue, because water is a lubricant for Thermo Plastic coated fabrics, and they actually wear better in the water because of this.
The word plastic refers to a property that materials have. It means permanent deformation under stress. That is what plastics do. Thermo plastics deform more than Thermo set plastics under stress. That does not have much to do with how they perform as a coating. It has a lot to do with how they perform as a fabric under the coating. Nylon ( thermo plastic) stretches more, and has a little higher tensile strength. Polyester (thermo set plastic) stretches less, and therefore needs less air pressure behind it to keep the boat stiff. Tensile strength is also determined by how strong the fabric base is. Therefore, a polyester fabric may actually have a stronger tensile strength than a nylon base fabric.
Coating technology has come a long way in the last 5 years. Most of the thermo plastics have better adhesion to the base fabric than do thermo set plastic coatings. New processes have been implemented that allow for a solution coating that completely saturates and coats the base fabric before a plastic coating is melted into place. these types of fabrics provide great air retention and coating adhesion. As a result there are fewer problems associated with air loss and delamination of the coating form the base fabric.
The Welding Process
Radio frequency welding uses a press that applies pressure to a large surface area. The press has a table that the material is placed on. Dies are used to direct the welding process. When the press comes together, Micro waves are passed through the small area between the die and the table where the weld takes place. These micro waves heat the material and the combination of heat and pressure cause the weld to take the shape of the die. RF welding is fast.
Hot air welding uses hot air to heat the coating on the fabric where it is to be bonded together. A Nozzle is situated between two rollers that pull the material through the machine. As the material is pulled through the machine, hot air is applied to the surfaces to be fused together. Pressure from the rollers and heat form the hot air cause the plastic to fuse as the plastic cools. With the material moving through a machine like this, different shapes can be made. Patterns can then be put together to form the shape of an inflatable boat. This is also a fast process. This process is not subject to the intricacies of radio frequency. However the operator must know a whole different set of rules to make it work.
The Gluing Process
Which is better?
Because welding actually matches and bonds coated surfaces together in a way that adhesives can not (no adhesive interface), it is a much more reliable method for constructing inflatable boats. Properties and strength of the original materials can be maintained, and not compromised by the presence of an adhesive and the labor to apply it. Add to this the savings in labor, and it becomes a very viable method of manufacture. We are constantly searching for methods to eliminate adhesives in our products, because of the reliability of welding, and of cost savings.
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