- Education and Science
What Do IV Bags, Air Mattresses, and Inflatable Rafts Have In Common?
Anytime I've gone camping, either with my friends or family, there have been a few constants in the things we've brought along. Like an air mattresses, since I can't quite handle what sleeping on the flat ground does to my back anymore, and an inflatable raft for going out on the lake. I recently learned how they get made: Radio frequency welding bonds the edges of the materials similar to how welding bonds metals, but by using radio frequency waves to rearrange molecules in the materials to meld them together. And once the process is complete, the seal is one uniform piece, rather than two pieces simply held together. In essence, two pieces of material meet and merge to become one. It's a seemingly boring idea and simple process, but it's a process used by many, many industries in plenty of different applications.
How Does It Work?
Radio frequency welding, or RF welding, can also be referred to as dielectric sealing or RF heat sealing. It's a technique that's been around since the1940s, and the way it works is by placing two pieces of material on a table press that applies pressure to both surface areas. When the press comes together and presses the two pieces of material together, high frequency radio waves, usually at 27.12 MHz, are applied to the area between the press and the material. The waves cause molecules in the materials to move and warm up, and because there is pressure applied, the two pieces of material weld together due to the heat and pressure combination. The entire process is completed very quickly, and because the materials are sealed with heat and pressure, the seam created is airtight and waterproof—perfect for keeping your lifeboat afloat and your air mattress nice and cushy.
How Is It Different From Regular Heat Sealing?
If the apparent outcome of the process is that it melts the plastics together, why is RF welding a more effective method of heating something rather than simply using direct heat? An RF welding sealer actually heats the material much more quickly than applying direct heat, and the plastic heated with this method also cools down much more quickly, which helps the material keep its shape better. In other words, if you spent more time trying to heat up the plastics to get them to meld together, you might end up with melted plastic rather than a clean, welded seal. Think of direct heat application as an oven and an RF welding sealer as a microwave—one of them is much more efficient than the other. Since it's a quicker process, this also means that a company's production rate will be higher than if they were using just direct heat.
What Are Some Advantages?
One big advantage of using RF welding instead of other methods to make a seal is that because it is so precise and targeted, the surrounding material doesn't get heated and become vulnerable to heat-breakdown. Since the process is fast, this also means that the material isn't subject to heat-degradation—it is heated and cooled quickly, rather than slowly rising and falling in temperature. Since pressure is not immediately taken off once the material is heated, the bond is able to strengthen while cooling. This creates a better weld than one that is allowed to expand after heating. Keeping the materials compressed gives the weld a chance to really stick, which is why this method is ideal for products that need to be airtight or watertight when they're finished. It's also a cleaner way of melding two materials. Since the only material needed to produce the seam is the material you're trying to seal, you don't have to use adhesives or other products.
What Industries Use It?
The most common materials used in radio frequency welding are PVC and polyurethane, but it is possible to use other materials like nylon, PET, EVA, and more, so it makes sense that industries like the outdoor-adventure types would use it for things like air mattresses and inflatable rafts. But plenty of other industries use radio frequency welding to create their products, too. IV bags in hospitals, for example, are perfect candidates for having been made using RF welding, and the same process can be used to create industrial curtain walls, like those used in warehouses or some auto body shops.
This process can also be used in military applications, for vehicles, to create weatherproof covers or seat cushions, or even for making something as simple as a beach ball. It's a process that's apparently used for products large and small, simple and complex—it's strong enough to fuse together a little boat and cost-effective enough to be used on shower curtains! Essentially, many different industries use this process. The integrity and strength of the weld lends this process to plenty of different applications, from medical uses to recreational uses, like those air mattresses that make my camping trips oh-so-comfy.