Plastic Identification... What Can Be Welded? What Can't?

When fusion welding with the nitrogen plastic welder, you will have to identify the type of plastic and select the correct welding rod. Although there are many types of plastic, there are only a few that are commonly used on auto parts. This video will help you to identify the plastics.

Always wear proper safety gear while working!

Let us know your thoughts on this video by leaving a comment on YouTube!

Helpful Resources:

• View our our Plastic Identification Chart for help identifying common plastics.
• Text and photo tutorials: Fusion welding thermoplastics with the nitrogen plastic welder | Repairing thermoset plastics with the airless plastic welder
• Videos: Nitrogen/Hot Air Welding | Thermoset Polyurethane Repair
• We have a huge selection of welding rod available to match a variety of plastics. View our Welding Rod List to see all of our options.
• Polyvance's current selection of nitrogen plastic welders

Video Notes:

• Because we have made several updates to our nitrogen plastic welders since this video was made, our current nitrogen plastic welders may not come with the exact type of welding rod listed in the video. Be sure to look at the welder's webpage to know what it is supposed to come with.
• This video clip was taken from our instructional DVD that we used to include with our welders. The DVD is outdated and no longer available; however, our video resources are available on our website or mobile app.
• English Closed Captions have been provided for this video. Click on the CC button to turn them on or off.
• The length of this video is in no way representative of the actual time required to perform a complete repair and therefore should not be used for estimating purposes.

English Transcript:

When fusion welding with a nitrogen plastic welder, you will have to identify the type of plastic you're working with and select the right kind of welding rod. There are many types of plastics, but only a few are used on auto parts. This section of the video will help you select the right kind of welding rod for the project you're working on.

About ninety-five percent of late model car bumpers are molded from polypropylene blends. These are meltable thermoplastic materials. These are usually black or dark gray, but sometimes they can be white. They will usually have a PP symbol molded into the backside. These plastics are sometimes identified as TEO or TPO. They are always a blend of polypropylene, synthetic rubber, and other fillers, and their proportions vary depending on the resin manufacturer and the application.

These PP blend plastics can be welded with our polypropylene or TPO welding rods. Since this is the most common plastic, we have many varieties of rods to match different applications. Your welder comes with three different profiles of natural polypropylene rod: round, narrow ribbon, and wide ribbon. You will also have a selection of black polypropylene rod and also some gray TPO rod.

Some bumpers are still made of polyurethane. This was a popular material years ago and it's still used on a few applications today. They're usually yellow on the backside, but not always. You'll see the ID symbol where it says PUR or RIM. Polyurethane is a thermoset plastic, meaning that it is not meltable. The solid is formed by reacting two liquid components, which cross-link in the mold. You will not be able to use the nitrogen welder on this type of plastic. You can repair it with the airless plastic welder. Instructions for this type of repair are shown in a later section of this instructional video.

Most other plastics used on cars are thermoplastics, or meltable plastics. In this case, plastic pellets are melted and injected into the mold. The plastic then cools and re-solidifies. Thermoplastics can be welded with the nitrogen welder. Common types are polyethylene, ABS, nylon, and polycarbonate. Polyethylene is often used on overflow and washer bottles. Nylon is used on radiator tanks, core supports, and other under-hood parts. Polycarbonate is used on body panels and bumpers. See the plastics ID chart that came in "The Book" of Plastic Repair literature with your welder for more details.

We're going to focus in this video on welding polypropylene, since this is the most common kind of plastic you'll be dealing with. Once you learn how to weld polypropylene properly, you'll be able to identify the other types of plastics and weld with those as well.