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Plastic welding for bumper cover repair?

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    Plastic welding for bumper cover repair?

    Two of my cars have cracked plastic bumper covers, and I've been looking into fixing them myself. I've come across plastic welding tools, and all the writeups I've seen online about using them makes it look easy. Just weld the plastic with the tool, add a little body filler, smooth, sand, primer, paint, done. Nothing is ever as easy as it looks, I've learned.

    Has anyone ever done plastic welding? Any tips? Is it worth buying more expensive tools to do it?

    Here's an example of a cheap plastic welding iron on ebay. $12, looks like a soldering iron.







    #2
    I haven't done any plastic welding, but they do make repair/filler materials for plastic bumpers instead of using standard body filler (which may not be as flexible).
    90 LX 4dr 5 spd 396,014 (sold 1/1/2022) - MRT: http://www.cb7tuner.com/vbb/showthread.php?t=201450
    08 Element LX FWD AT 229,000 - MRT: fleetw00d : 2008 Honda Element LX - CB7Tuner Forums

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      #3
      I hadn't thought of that. I'll have to look for it!

      My Miata has a corner piece that's basically dangling, and my Accord has massive cracks (I could get a replacement bumper cover, painted, for $200 or $250 shipped... but fixing it myself would be even cheaper.)






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        #4
        A soldering iron and some plastic welding rods pretty much sums it up. Do make the crack(s) V shaped areas like the profile of a knife, start getting the V area on bumper warm close to melting do the same with the rod (even zip ties work on certain plastics) and start welding. Watch going to low a grit while sanding on plastics nothing lower than 180-220 (I usually go 220 or 320 then step up to 400 and 600) or the material will start fuzzing if you get to aggressive and it's hard to get rid of at that point so save yourself some time and be patient while sanding plastics. Use the plastic filler as you see fit I've never had an issue with zglass or the evercoat glazing putty (white putty red pre mixed is junk) on bumpers to be honest.
        Last edited by SOHC-FTW; 04-14-2018, 04:44 PM.

        02 Crv
        02 silverado Ex cab Z71, 2011 TRD 17" wheels, 245/80/17, ls1 cam, AFE intake, 3" catback, tuned by Larry at LSXperformance&pcm tuning driven daily.
        92 Acura Legend colbalt blue LS Coupe, custom intake, custom vibrant 2.5 cat back, led cluster and high beams, 2016 Coyote GT 18x8 wheels 235/40/18.
        Coming Soon Tein TSX coilovers.

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          #5
          Cool, thanks!

          I just picked up an Aoyue 469 60 watt soldering station to build guitar pedals. I'll have to see if a plastic-welding triangle tip is available for it. I think it's a common sized iron.






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            #6
            you can probably find a tip, or I know harbor freight sells a "plastic welding kit" if you wanted dedicated tooling for it. Years back mauricio and I tried it with just a regular old stick iron (I think they are usually 12 or 15 watts) it worked, just wasnt powerful enough.


            - 1993 Accord LX - White sedan (sold)
            - 1993 Accord EX - White sedan (wrecked)
            - 1991 Accord EX - White sedan (sold)
            - 1990 Accord EX - Grey sedan (sold)
            - 1993 Accord EX - White sedan (sold)
            - 1992 Accord EX - White coupe (sold)
            - 1993 Accord EX - Grey coupe (stolen)
            - 1993 Accord SE - Gold coupe (sold)
            Current cars:
            - 2005 Subaru Legacy GT Wagon - Daily driver
            - 2004 Chevrolet Express AWD - Camper conversion

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              #7
              I do it all the time at work. The "proper" way to do it is with what's called a nitrogen welder. The idea is that heating the plastic with pure nitrogen instead of ambient air is that the nitrogen melts the plastic whereas the oxygen in air "burns" the plastic. I don't know if there is truth to that but that's what I was told with my "certification"... whatever the hell that means... haha. I will say when you use nitrogen there is no smoke. Using just hot air, the plastic smokes like a bitch! I have actually never used an iron, so I'm not sure if it would work, but I would think it wouldn't fuse the plastic together very well. The key is to get the bumper plastic and the plastic welding rod melted at the same time. There is also a couple different types of plastic. Most these days are polypropylene. This plastic is "weldable". Is that a word? Anyway, the other one is polyurethane I believe. For all intensive perposes, we'll say this is not weldable. I want to say ours is polypropylene. It will say on the back. There will be an emblem something like <PP> this stands for polypropylene. If you are interested in the techniques, search "Polyvance" on YouTube.

              345,000 miles and counting...

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                #8
                I've also used the nitro smokeless but that was many years after doing it The iron way that I was taught so I stuck to an iron and rods throughout my right at 15yr career in bodywork. Up until my last two years of owning my own shop it was suggested I find something else to do due to health issues. That being said plastic does smoke and stink to high heaven, but with that also being said I've never had a bumper all the way up to bike kits come back on me ever with an old iron and rod.

                Theirs a 100 different ways to skin a cat, but this is my way and it works as it should to do a proper fix if done properly.

                02 Crv
                02 silverado Ex cab Z71, 2011 TRD 17" wheels, 245/80/17, ls1 cam, AFE intake, 3" catback, tuned by Larry at LSXperformance&pcm tuning driven daily.
                92 Acura Legend colbalt blue LS Coupe, custom intake, custom vibrant 2.5 cat back, led cluster and high beams, 2016 Coyote GT 18x8 wheels 235/40/18.
                Coming Soon Tein TSX coilovers.

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