Create New Tabs on Urethane Bumper Covers

Urethane bumper covers are often discarded because of broken tabs and bolt holes. Thermoset polyurethane was commonly used on domestic bumpers back in the 1980's and 90's. It's pretty much been replaced by polypropylene now, but you'll still see the old yellow plastic out there once in a while.

Polyvance was formed in 1981 as Urethane Supply Company to address the needs of bumper recyclers and to supply products to repair urethane bumper covers. Around that time, many people did not think urethane bumpers could be repaired. We proved they can be repaired.

Polyurethane is a thermoset plastic, meaning that it is NOT meltable. The solid is formed by reacting two liquid components which crosslink 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. This will not provide a fusion weld. The urethane welding rod is used more like a hot melt glue.

You can use our Mini-Weld Model 7 or the integrated airless welder that is part of our nitrogen plastic welding systems to perform the repair. These two options are recommended because you need to be able to control the temperature of the welder.

This article can help you determine if your plastic part is thermoset polyurethane or a thermoplastic.

Always wear proper safety gear while working!

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Products Used:

Note: This is a list of the Polyvance products that can be used to make this repair. This list does not include sanders, grinders, or other common tools you will need. If you have any questions, please don't hesitate to call technical support at 800-633-3047.

• 6121-T Tear Drop Cutter Bit
• Aluminum Body Tape (several options available)
• Polyurethane Welding Rod and an Airless Plastic Welder(choose a method below):
• Polyurethane Welding Rod with the airless plastic welding side of a nitrogen plastic welder. Our current nitrogen plastic welders include the 6027HT Standard Welding Tip.
• 5700HT Mini-Weld Model 7 (230V kit available here). The 5700HT kit includes a 15 foot starter roll of polyurethane welding rod and the 6027HT Standard Welding Tip.
• Note: Make sure you are using either the 6027HT Standard Welding Tip or the 6029 Bigfoot Welding Tip when using the round polyurethane welding rods.

Video Notes:

• This type of repair can be done with the Mini-Weld Model 7 or the airless side of a nitrogen plastic welder.
• 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:

Urethane bumper covers are often discarded because of broken tabs and bolt holes. These bumpers can easily be repaired using an airless plastic welder. Because thermoset urethane bumper covers do not melt, you do not get a true fusion weld. Instead, the repair is similar to a brazing process.

Grind the area to be repaired to expose clean plastic and taper the plastic to a point. Expose sufficient area of plastic for the rod to bind. Grind the opposite side also, making sure to expose an area sufficient for the rod to bond to, and grinding the plastic to a point. Apply aluminum body tape to the location where you'll be creating the new tab. The aluminum tape is stiff and can handle the heat of the welding.

After the tape is in place, melt the polyurethane rod onto the tape, making sure to melt the rod onto the existing plastic as well. Continue melting rod onto the tape until you connect the tab and the thickness matches the original thickness of the tab.

Allow time for the rod to cool before peeling the tape from the opposite side. Just as you did on the other side, melt rod onto the existing plastic across the tab and the existing plastic at the other end of the tab. Smooth the tab and feather the rod onto the plastic while the melted rod is still hot.

Use a rotary tool to remove excess plastic and to shape the tab. Be sure to remove excess plastic from the opposite side as well. Finish shaping the tab with an abrasive disc. Here, we are using a right angle drill at a low-speed. Avoid using high-speed grinders to prevent melting the plastic.

Even though this is not a true fusion weld, you can see here that you can create a very strong tab on urethane bumper cover using the airless plastic welder.