Hot air plastic welding is the process of joining two or more plastic surfaces together using hot air, usually applied by a heat gun.
Plastic products cannot always be made in one piece. It is often better and more economical to manufacture products as individual components.
Hot air forming is inexpensive and effective, creating a very strong bond between plastic materials that will not separate. These tools are easy to use and cost-effective. They should be the protagonists of any toolbox.
It is also versatile. Hot air plastic welding can also be used to repair cracked and damaged thermoplastics.
No expensive fillers or special handling are required - all you need is a heat gun and some cheap plastic sticks.
After post-processing work (often including sanding and repainting), hot air plastic welding jobs look almost invisible.
The hot air welding process
The hot air welding process is usually divided into three distinct stages. These are pretty much universal no matter what you're soldering.
Prepare the surface to be hot air welded
Apply heat and pressure
Cooling and finishing
There are two main types of hot air welders - automatic and hand-held hot air welders.
Automatic welding machine
Automatic welding machines are usually only used to seal roofs and floors - a large surface area needs to be covered and two flat sheets are welded together.
Automatic welders include a hot air funnel that directs hot air and applies heat under the welding film and a roller that applies pressure and glues the film down.
Handheld hot air welder
Hand-held hot air welders can be used for roof and floor work -- often for welding corners and other hard-to-reach places -- but they can also be used for a wider range of jobs.
Handheld welders can be used for manufacturing and repairing products, sealing plastic films, and many other one-time jobs.
They are usually shaped like large elongated tubes with many different nozzles that can be changed depending on the type of work that needs to be done.
How to prepare plastics for welding?
Preparation is key to ensuring a good clean weld. Make sure to clean most of the plastic area with a good quality plastic cleaning product. If the plastic is painted, such as on a car bumper, then you should sand off the paint for a reliable weld.
How do hot air plastic welding?
Once the plastic is ready, it's time to weld.
If you are welding two separate pieces of plastic together, then you may need to hold the two materials together before welding them properly.
Do this by holding the two pieces in place and running a positioning nozzle along the edge you wish to connect. The stick nozzle will melt the plastic just enough to stick it together.
Once the materials are secured together, you need to make the joint permanent by welding. One of the easiest ways is to use a technique called "pendulum welding".
For pendulum welding, you use a standard nozzle to concentrate the heat on a small spot.
Apply downward pressure to the correct plastic electrode, feed it directly into the bevel, heat it through a standard nozzle about 5-10mm away, and wait for it to melt into the bevel.
Weaving welding is used when you have only very short welding or sealing area or do not have fast welding equipment.
Weldability of plastics
The quality of the weld depends not only on the method used or the skill of the welder but also on the weldability of the base metal.
Also known as bondability, the weldability of a material refers to its ability to be welded. The weldability of thermoplastics is judged by their rheological weldability.
The rheological weldability of material is judged by its rheological properties - viscosity and activation energy.
Safety when heating plastic
There are several safety issues to consider when welding plastics.
If you're not sure what's in the plastic, you need to be careful when heating it, as this reaction can release deadly gases.
Make sure you work in a well-ventilated environment and wear a mask at all times.
You should also know that heat guns can get very hot and can cause serious damage to your skin if you're not careful with them.
The above introduces the principle of hot air plastic welding and the types of plastic welding machines. If you want to know more or want to buy a hot air gun, please contact us
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