Plastic Repair: How to identify, prep, weld, and repair plastic

Plastic repair and welding can be a simple process if you have the right high-quality equipment and if you take the time to get it right from the beginning. In addition to the necessary equipment, what else do you need to consider when approaching your plastic repair?

In this article, we’re going to look at how to prepare plastic for repair and how to do it properly so that your repair lasts.

Plastic repair preparation

Before you jump into your plastic repair, you’ll need to make sure you have the correct tools for the job, and that you have prepared the surface of your plastics correctly.

Tools and Equipment

There is no replacement for high-quality tools. High-quality tools will allow you to get the job done faster and with minimal interference. It’s a good idea to stock up on the safety equipment needed too.

For most plastic repairs, you’ll need:

• Kit – A temperature-controlled plastic welding kit with a selection of nozzles.
• Rods – Plastic rods of the same material as the plastic you want to weld.
• Gloves – High welding temperatures call for adequate hand protection.
• Eye Protection – Eye protection suitable for welding is vital.
• A Flat Surface – A flat and clear surface to work from that is heat resistant with some clamps would be a bonus.
• Ventilation – Some plastics can give off foul smells when melting, ensure your room is well ventilated.

Surface Preparation

The plastic surface you wish to weld should be clean and clear of debris. Use simple soap and water to clean off most stains. If a stronger solvent is required try using methyl ethyl ketone (MEK), but DO NOT use any industrial-strength solvents as this could damage the surface of your plastic.

You may also wish to remove any paint and debris with light-grit sandpaper.

Determine Plastic-type by Test Welding

Once you’re ready to get going you’ll need to know how to identify plastics by doing a test weld with your Heatgun. Getting the right plastic type is vital for a stronghold.

Test weld by welding the end of the rod to a small inconspicuous area, if it holds firm you have the right material.

The Three Main Steps in Plastic Welding

There are three main steps for a good join between thermoplastic:

• Pressing – ensuring sufficient pressure when pushing the plastics together.
• Heating – achieving the right melt temperature.
• Cooling – the length of time the join is allowed to cool before releasing the pressure.

During the pressing step, the application of pressure – often used throughout both the heating and cooling stages – is used to retain the parts in the proper orientation and to improve melt flow across the interface.

The purpose of the heating stage is to allow intermolecular diffusion from one part to the other across the faying surface (melt mixing).

Cooling is necessary to solidify the newly formed bond; the execution of this stage can have a significant effect on weld strength.

What to Consider When Learning How To Weld Plastics?

There are several things to consider when welding plastics. Let’s take a look at considerations for the heat, the welding rod, the welding gun, and the welding kit.

• The Heat – You will likely need the temperature within the range of 200 and 300 °C (392 and 572 °F). Below or above that range will result in the plastic not melting enough or burning the plastic. You’ll need to know what temperature you require based on what type of plastic you are welding.

• The Welding Rod – It’s crucial that the welding rod is the same material as the plastic to be welded. It’s also vital to ensure that the welding rod’s end has been trimmed so that it’s in pencil-point form.

• The Welding Gun – Manual (hand-held) welding tools are used for small fabrication work, detailed projects, and repair work, and should not be used for thicknesses beyond 10mm. For larger fabrications, using extrusion welding tools.

• A Welding Kit – For beginners, plastic welding kits and a plastic repair kit are a great option because they are fully equipped with what you need for most repairs. Kits come with a welder, varying welder rods, plastic welding tips, and a guide to help you through your welding process.

Plastic Welding for the Automotive Industry

While adhesive repairs are perfectly fine for minor vehicle repairs, plastic welding is incredibly common in the automotive industry. Filler rods are now more adaptable to the repairs that are needed, and the cost of plastic welding continues to fall. When quality and speed of repairs are criteria, plastic welding is the solution. There are lots of different plastics used in the build of modern cars, and that can mean variations in the types of welding and welding rods used. As with all welds, though, the process starts with cleaning the surface before carefully working out any deformations or dents. Often, the automotive industry uses nitrogen plastic welders, as these will tend to result in a stronger and more durable weld. However, there are differences when it comes to nitrogen welders. Some require external nitrogen tanks, while others generate their own. Self-generating nitrogen welders will be more cost-efficient over time. If you’re interested in learning more about the automotive industry and plastic welding, click to read our detailed guide, plastic welding for cars.

Plastic Welding for the Agriculture Industry

Across the entire agricultural sector, plastics are used a tremendous amount. One of the most common uses of plastics in agriculture is in the bins that are used, read our plastic fabrication case study for agriculture bin repairs. That use is growing because of the rise in the growth of organic crops, which plastic helps to protect and keep dry while also having a longer life. However, accidents do happen, and those plastic bins can get damaged. Plastic welding helps to avoid the need to discard damaged bins, but there are limitations. Plastic bins with cracked bottom corners may not be repairable simply because they bear the brunt of the weight. Side cracks and the bin’s feet can be repaired, though, and it’s an incredibly easy process. Use your plastic welding gun to soften the plastic rod and then bead along any cracks. The temperature of the weld is important to get right because if it’s too high then the integrity of the bin will be compromised. Too low, and the weld will not be secure. It can take time and practice to get this right.

Plastic Welding for the Roofing Industry

For pitched roofs and flat alike, there can be a range of different plastics used in the roofing sector. In some cases, modified bitumen will be present, while thermoplastic membranes (PVC) are more common. Plastic welds for PVC roofing are often the best repair option because when it is done currently, it is watertight, and it doesn’t require the use of any caulking or glue. Both glue and caulk are prone to deterioration when exposed to the elements, while plastic welding provides continuous sheeting without degradation, protecting property more effectively. Both handheld plastic welders and walk-behind welders are used by roofers, depending on if the repairs are for trim work or for longer seams with overlapping sheets. Plastic welding has now become the industry standard when it comes to roof repairs. While handheld welders are easy to use with a little practice, walk-behind welders will tend to require a little more training.

Plastic Welding for the Flooring Industry

Plastic floorings, such as PVC-P vinyl, PE, or linoleum, is commonly used in industrial settings because it is clean, makes installation simple, is waterproof, and very easy to maintain. When damage does occur, clean and neat repairs are carried out easily with plastic welding. Hot welding and cold welding are the most commonly used welds for plastic flooring, and either can be used effectively to seal seams and repair cracks. For joining individual sheets together, cold welding is the more practical choice as it allows for a closed, sealed join. Hot welding can be used for those joins, but it is more commonly used for sealing plastic floors, which means that they benefit from added durability. This is particularly useful in hospitals, laboratories, and medical settings. Hot plastic welding is also used for flooring to hermetically seal the flooring seams, minimizing dust and bacterial buildup, and help protect against any harsh chemicals and cleaning agents. Click to learn more about some of the best plastic welding tools for flooring by LEISTER.

Plastic Welding for the Civil Engineering Industry

The civil engineering sector uses plastic welding for a wide range of applications. From tunnel sealing or landfill storage to swimming pool repairs, plastic welding is the go-to response simply because it has such value. Quality seals are so important for civil engineers to achieve because leaks can have very serious consequences. Civil engineers also work on landfill sites, where a sealing system is one of the most important parts of the installation. Hot-wedge and combi-wedge welding machines are both used in landfill storage and are used to approach different plastic geomembranes and their relative thicknesses. Many of the welding tools used in the civil engineer’s role will be more technically advanced than in other sectors, mostly due to the necessity of double welds and the need for rigorous safety compliance. Learning to more efficiently and safely weld in a civil engineering role will require extensive training and a PE license. Click to see LEISTER’s high-quality plastic welding equipment we offer.

Plastic welding for repairs, such as a plastic bumper repair, or as part of a manufacturing process can be a great way to get the products you need, but it’s vital that you use quality equipment. Here at Heatgun, we’ll be happy to answer any questions you have and point you in the right direction to the right equipment for your task. Drop our friendly team a message today.