Facts About Plastic Welding

It’s common knowledge that you usually can’t work plastics the same way you would metals. When a plastic object cracks or breaks apart, it’s typically thrown away or recycled—at best, glued back together with the hopes that it’ll hold and still function. However, there’s a trick that many folks aren’t aware of: plastic welding. Though it doesn’t sound possible, it’s performed regularly in industry and can even be done at home.

How Can Plastic Be Welded?

When someone talks about welding, they usually don’t have plastics in mind. However, the basic process used in welding metals can apply to various plastics as well. Welding, in essence, is using heat to partially melt two pieces of work material in order to join them together. Plastics can be melted, too, and many are safe to work with. In an industrial setting, welding can be used to assemble or repair plastic objects, whether it’s equipment such as plating tanks or consumer products like automotive parts or household appliances. Various methods of welding exist: laser welding, ultrasonic welding, hot gas welding and spot welding are just a few.

What Plastics Can Be Welded?

There are two broad categories of plastics, based on molecular structure: thermosets (or thermosetting plastics), which harden irreversibly upon cooling; and thermoplastics, which can be made pliable again by heating. Naturally, weldable plastics all fall under the latter category. Common thermoplastics include polypropylene (PP), polyethylene (PE), polyvinyl chloride (PVC), nylon and acrylic.

Welding Plastics at Home

DIY aficionados that prefer repairs over replacement can turn to welding not only to fix broken plastic objects but also for artistic or fabrication projects. Many tool stores and similar retailers sell specialized plastic welding kits for this purpose, but a soldering iron can also do the trick. Make sure to experiment with scraps first before taking on serious repairs, and keep in mind that welds require parts of the same material and a clean joining surface.