Hot Air Welding

Plastic Welding: How To

Which materials can be welded? Only Thermoplastics can be welded. You must weld like for like plastic to achieve a structurally sound bond. CARR New Zealand offers plastic weld rod test packs containing a range of common plastics, these test packs can assist you in identifying which plastic you are working with.

The welding process (rigid plastics)

Step 1.

Prepare the weld surface. Ensure it is clean of dust and dirt so that you can achieve an unobstructed plastic-to-plastic bond. Notch out a “V” groove along the crack or join.

Step 2.

“Tacking” the join or crack together helps to secure the material in place to ensure there is stability and no misalignment of the joins. Run the tip of a tacking nozzle or heated metal item along the join to create an initial bond.

Step 3.

Using a speed welding nozzle or by free hand pendulum welding technique, introduce the plastic weld rod to the weld zone. Ensure equal levels of hot air are directed at the plastic weld rod and the weld surface to ensure they reach “plasticity” at the same time.

Step 4.

When the surface plastic shows signs of slight wetting, move the welding nozzle along the groove while at the same time applying downward pressure on the weld rod to ensure a sound bond.

The below video shows an example of a box repair with an extrusion welder.

Types of Hot Air Welding Equipment

Hand Tools

Leister hand held hot air welding tools are the most common tools used in a wide range of industries to create and repair plastic products. The Triac AT and ST, the Hot Jet and Penweld all provide the ability to weld in a wide range of applications.

These tools are complemented by a wide range of nozzles and welding tips to make the tools very versatile.

Extrusion Welding

Leister has developed a number of Extrusion Welders such as the Weldplast and Fusion range. The Weldplast tools are digital and meet the DVS welding requirements. The Fusion tools are non-digital and can be used where the DVS standard is not required. The Extruders can have output of 1, 2, 3,4 and 6Kg’s of welding rod per hour.

Extruders are used to produce large plastic structures made of thick material. The welds on thicker, larger plastic structures require larger welds and material which is why the extruder is the only option.

Leister have complimented their extruders with a larger range of welding shoes to allow for all the different weld types and sizes required for producing these large structures.

Roofing

Roofing in the global market continues to change and we have seen the introduction of more membranes used to waterproof residential and commercial buildings.

These membranes are installed using hand tools and automatic welders. For the larger projects, Leister has developed a range of Automatic Welders, for the roofing industry, Uniroof 300/700 and the Varimat 300, 500 and 700. All the Leister welders are fitted with 40mm nozzles, however Leister do produce an 80mm Conversion Kit for bitumen welding.

The 700 models in both categories are fully equipped with the Leister Quality System (LQS). This system allows the operator to digitally record all the parameters for the welding seams, produce reports and the ability for live oversight by connecting to the myLeister app.

Civil Engineering /Geo Membrane Welding

Leister produces a large range of tools and accessories for the Civil and Geo Membrane Welding Industry. The range of tools include the Twinny S, Twinny T5/T7, Comet 500/700 and the Geostar G5/G7.

The complimenting accessories are the Examo 300/600, Coupon Cutter, Leak Tester, Vacuum Plate and Bell.

The range of welders provide solutions for welding the thinnest membranes and up to the thickest.

The T7, G7 and Comet 700 all come with on board LQS for data recording and reporting. This is another great function to assist in this industry where the scale is large and the risk of leak failure is high. The LQS system seeks to help mitigate the risks for all involved.

Tarpaulin & Banner Welding

Leister have produced a number of Hot Air Welding Machines for the Tarpaulin industry and for the sign and banner industry.

The Uniplan 300/ 500, Variant 700, 702,704,706,708 are all designed for the tarpaulin industry. These machines can be used to weld a wide range of products and materials within the industry.

The Uniplan provides machines that can overlap weld, Hem and also rope welding. The range of Variants provide machines to overlap, hem, weldable webbing, weldable reinforcing tapes, dual wide strip welding and dual nozzle reinforcing welding.

The Variant is produced in 230V and 400V models. The 400v models should be the model considered if there are future plans to use the range of conversion kits available.

In the Sign and Banner Industry Leister have developed the Hemtek ST bench mounted welder for hemming signs banners. These machines are made for operation in a standing position.

Technical Textiles

Leister Technologies have also moved into the Technical Textile space by designing the Seamtek Wedge and Hot Air Welders.

These large machines offer a range of options. They have the ability to weld from 8mm to 64mm using the array of wedge and wheel sizes. These interchangeable machines allow the machines to be flexible to produce a number of products using the same machine. The machine can record 100 different welding recipes which again allows for a quick change between products.

Where Leister has excelled is the development of the low voltage wedge on the Seamtek W-900, and W-2000. The machine only draws power during the welding and then stops. The cost savings of this machine versus traditional copper wedges and hot air version is considerable.