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Welding Plastic- How do you do it?

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  • Welding Plastic- How do you do it?

    I just picked up a HF plastic welder. The kind with the air blower built in. http://www.harborfreight.com/plastic...ent-96712.html
    I opened up the instructions and learned not to burn my hands and not to weld in the rain, etc. But there was not much on technique on how to actually weld plastic.

    I had a leaking PE gas tank and found some like material and by trial an error was able to seal the leak. I then tried it again on another tank and that was a disaster. The material was not the same and it was not as thick and I quickly burned through the material.

    So, how does one weld plastic? They supplied 3 tips but failed to explain when they should be used. What type of motion should one use to heat the material and add filler plastic. Do you deal with a traditional puddle? How do you do it????

    Randy
    Do yourself a favor and see if your TV carrier has America One News Network (AONN). 208 on Uverse. It is good old fashion news, unlike the networks, with no hype, bias or other BS.

  • #2
    I'd like to know to. Have been thinking of getting a plastic welder.
    Andy

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    • #3
      I have had only a little experience with plastic welding but I found it to be about the same as steel welding except for the temperature. You do have to have the same type of material for a filler rod and the work. Everything needs to be clean and you need to practice to learn what works and what doesn't. You do have a 'puddle' but it is not as visible and will be pretty small for thin work. The 'puddle' doesn't seem to be as fluid to me. Temperature seems pretty critical and you probably need a way to regulate both the air and the electric power to get your 'torch' to work best. It seems very easy to overheat the plastic. It does not seem to be a process that 'just works' without some skill being developed.

      I have one plastic welder that only uses a tool like a soldering iron with a hole for pushing the rod through. That one seems a little easier to use but not quite as versatile.
      Last edited by Don Young; 09-30-2012, 11:17 PM.
      Don Young

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      • #4
        No personal experience with their products, but...

        There's lots of info here: http://www.urethanesupply.com/
        I don't do drugs.
        At my age, I can get the same effect if I stand up too quick!

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        • #5
          I dont weld plastic much myself but I work at a plastic fan company so I will pass on my observations.
          The welding itself is done in one of two ways the first just uses a simple nossle which is used in a similar way to gas welding you create the molten pool which as stated by don is not as easily visible as metal and add the plastic rod to the pool, the difference is that the rod does not melt completely but just pushed into the melted plastic.
          the second way is as don states using a nossle with a feeder hole built into it and is more akin to mig welding. this allows you to feed the rod into the melted pool as well as simply dragging the rod along the weld line (you dont even have to hold it just drag the gun) however the gun in the link you gave does not seem to include this nossle. It also does not seem to include a tacking nossle which has a smaller hole and a flat bit protruding which can be run along the weld line (right angles only i think) to stick the two parts together prior to final welding.
          Its a pity the best bloke in our factory is computer illiterate because he would be able to give you a world of information including which plastics will weld easily and which will not weld at all. I believe that the abs? that is mostly used for moulding is a terrible plastic for welding.
          This page looks like it give good info as well as a picture of the various nossles http://www.ipfonline.com/IPFCONTENT/...nd-triac-s.php.
          hope this helps a little.
          Last edited by shipto; 10-01-2012, 06:25 PM.

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          • #6
            I do it all the time. We have a lot of piping that is rather large diameter that would cost a fortune to replace if we had to buy all the fittings and reglue so when they crack or the glue joint fails, I use our hot air plastic welder. Like everyone else has said, practice helps but there are certain things to know, no matter what the situation is. 1. match the filler material. 2. prepare the joint for cleanliness and max penetration (just like welding metal). 3. too much heat can be worse. 4. If the color of the material is changing color then your are overheating it (can make the HAZ brittle). 4. You just need to get the joint and the rod gummy/ sticky (or a little past that) and no more. 6. Mulitple passes are just like with stick welding (root, hot and intermediates, no cap's). I have welded up to 8" schedule 80 dark grey PVC (type 1), and the key is to make multiple passes to minimize the heat and to stagger your start and stop points. On fillets, you don't have to go any thicker than the base material thickness. These are all basic rules. The weld will not necessary flatten and will still have a rod/roll apearance. Several tips can be used. The single orifice tip is to preheat everything and weld with, push the rod into the joint with the heat gun in front of it. The other tips are usually variations where you can automatically feed the rod at the same time its heating the material. I will see if I can download the procedure onto my computer and email it to you. PM me your email if you want it. I also have a book by Audel publishing that is a Pipefitters/ HVAC book that shows the procedure with pictures as well. Good Luck!
            Last edited by bobhdus; 10-18-2012, 02:15 PM.

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            • #7
              Originally posted by bobhdus View Post
              I do it all the time. We have a lot of piping that is rather large diameter that would cost a fortune to replace if we had to buy all the fittings and reglue so when they crack or the glue joint fails, I use our hot air plastic welder. Like everyone else has said, practice helps but there are certain things to know, no matter what the situation is. 1. match the filler material. 2. prepare the joint for cleanliness and max penetration (just like welding metal). 3. too much heat can be worse. 4. If the color of the material is changing color then your are overheating it (can make the HAZ brittle). 4. You just need to get the joint and the rod gummy/ sticky (or a little past that) and no more. 6. Mulitple passes are just like with stick welding (root, hot and intermediates, no cap's). I have welded up to 8" schedule 80 dark grey PVC (type 1), and the key is to make multiple passes to minimize the heat and to stagger your start and stop points. On fillets, you don't have to go any thicker than the base material thickness. These are all basic rules. The weld will not necessary flatten and will still have a rod/roll apearance. Several tips can be used. The single orifice tip is to preheat everything and weld with, push the rod into the joint with the heat gun in front of it. The other tips are usually variations where you can automatically feed the rod at the same time its heating the material. I will see if I can download the procedure onto my computer and email it to you. PM me your email if you want it. I also have a book by Audel publishing that is a Pipefitters/ HVAC book that shows the procedure with pictures as well. Good Luck!
              Btw, Our welder is made by Seelye. Here is the video and info page http://www.seelyeinc-orl.com/videos-and-tutorials.html

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              • #8
                Hey Bob,
                Does your welder work as well as the one in the video? They make it look sooo easy. My experience is much different with my HF. My welds with HDPE are getting better, but it is not really a weld. It is more like a patch. If I pull on the filler material it will pull off as if it were glued on. But it is strong enough to seal a gas tank as long as there is no pressure.

                Randy
                Do yourself a favor and see if your TV carrier has America One News Network (AONN). 208 on Uverse. It is good old fashion news, unlike the networks, with no hype, bias or other BS.

                Comment


                • #9
                  Originally posted by randyjaco View Post
                  Hey Bob,
                  Does your welder work as well as the one in the video? They make it look sooo easy. My experience is much different with my HF. My welds with HDPE are getting better, but it is not really a weld. It is more like a patch. If I pull on the filler material it will pull off as if it were glued on. But it is strong enough to seal a gas tank as long as there is no pressure.

                  Randy
                  The one I use at work, works great. Just as easy as in the video. You have to adjust the power settings though and adjust the air pressure accordingly. It is the only one I have experience using and is with my employer but after posting my last comment, I got on ebay and bought one for myself for use in my Home business (Locksmith/ welder/ appliance repair). It was a Seelye brand as well and had the built in air compressor. I got it for $100 (normally over a $1000). It has a defective heating element (only costs $55 from Seelye.) Honestly, I mostly weld schedule 80 PVC piping with the one I use at work. I have never had a problem. The only time I ever had a leak was when I didn't know that you need to stagger your start and stop points. Keep the heat low enough to melt the rod and bonding area without changing the color and move slow, "push" the rod into the joint, and make sure you push the ends of the rod into the joint when you start and finish it. If you follow that Seelye video to Youtube, there are more videos from them that show excellent tutorials. and how-to's with joint repairs. We did some lexan here awhile back and it worked perfect. Used it on Teflon sheets for one of our Powder Coat Booths and that job was perfect as well. Unlike PVC Glue or (other glue epoxy types), you can use the joint immediately.

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                  • #10
                    I have 3 photos in my profile of a PVC Pipe repair. Two of them are 5G position and the last one was welded in the 2G position. Next week I will see if I can add more photos of various plastic repairs.

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