What is Hot Air Welding?

• Hot air welding, is also often referred to as hot gas welding (this is due to the original torches being gas powered)
• Hot air welding is a method of jointing thermoplastic products together using blown hot air. The hot air tool itself can be a versatile hand held tool with many nozzle attachments, or it could be a specially designed machine for a specific job.
• Focusing on a simple handheld hot air welder, a fan forces air over special heating elements and through a nozzle onto the workpiece to be welded.
• The hot air softens both parts of the plastic to be joined.
• The materials to be joined should be compatible. (hot air welding is not a glue, it is a fusion process, in the same way that you would not try to weld aluminium to steel)
• If required, a plastic filler rod can also be used and is usually fed into the weld using a special nozzle on the tip of the gun (sometimes referred to as speed welding). As with the materials to be welded, the filler rod must be of the same or a very similar plastic.

Preparation and Welding tips

• As with any kind of plastic welding, preparation and cleanliness is key.
• Ensure that the plastic sheet and the welding rod is kept clean, dry and dust free.
• Once any protective films are removed from the workpiece, use a scraper to remove a small surface layer of plastic from the welding zone (similar principle to electrofusion preparation)
• Ensure the workpieces to be welded are firmly clamped (use a tacking tool to tack the materials correctly together, but do not rely on tacks alone)
• Prepare any chamfers required
• Check the output hot air temperature with a suitable temperature probe. (is it according to the correct welding standards?)
• Take care not to overheat the plastic, overheating can weaken the molecular structure of the plastic and cause it to lose its properties.

 Hot air welding has many uses, a few examples of where it can be used are below:

- Car bumper repair

- Vehicle mudguard repair

- Jointing in sealed floor systems

- Tank construction

- Geomembrane jointing

- Roof lining

Advantages:

• Low cost to get set up for simple hot air welding
• Low cost filler rods
• Wide range of materials can be welded
• Very flexible, can get into tight corners
• Can be used to repair and restore old thermoplastics
• A successfully executed weld should be as strong as the material itself
• Plastic parts can be welded together and assembled into one whole item
• A standard hot air gun is a multipurpose tool, can be used to warm and dry, bend and shape materials without the need for an open flame.

 Disadvantages (very few):

• Can be quite time consuming if a large weld value is needed, many runs must be laid (at this point you may consider an extrusion welder)