Plastic Welding- Anybody successful with it?

[randyjaco]

I tried this elsewhere without good results, so maybe someone here is a plastic welding wizard.

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

 

[Tom Griffin]

Randy,

I've used it for welding PVC before and it worked pretty well. Welding plastic is not like welding metal in that you don't form a puddle. All you do is melt the base material and shove the filler rod into it as you go. The tips I had on the torch had a hole in the side for the filler and you just sort of pulled the torch along the seam as you pushed the filler rod into the hole. There really wasn't much technique involved. The only thing is, the filler absolutely must be the same material as the base, PVC on PVC, polyethylene on polyethylene, etc.

Tom

 

[Old Iron]

I've had the H.F. plastic welder for a few years, The one thing I need to warn you about is if you get good at it Don't Tell Anyone.

People will bring things by the truck load to you.

Paul

 

[jocat54]

I have one , but it's not HF, the hardest thing I have found is trying to id the plastic to get the right rod (don't count on color). I'm still not very good at it but can get by.

 

[pjf134]

I have done a lot of plastic welding in the past and got certified in all types. I have a hand welder like the HF one but a better one for sure. Mine has different elements for it for use in different plastics and used about 10 psi of air. Cross link PE like in molded tanks are not weldable, but I have done it before with success. The trick is use a tacking tip then put a bead of weld over it to fill in the groove, then scrape it flush and run a little heat over the ends of the weld. There should be a little flashing (melting) on the sides when running the bead and does take some practice, but not too hard. I have a welding book for plastic and will check to see if there is some pics showing the way to do it tomorrow.
Paul

 

[randyjaco]

Thanks Paul et al,

Polyethylene will probably be what I need to weld most. Some of those old plastic gas tanks are impossible to find and after a couple of years they start to crack. Besides PE is showing up in all kinds of applications. I would appreciate any pointers and help you can supply.

I guess I am going to have to find some bad tanks and keep on practicing.

Randy

 

[pjf134]

Randy,
I have a Laramy welder from the 80's and may look and act different from the HF, but should weld the same. Make sure no water gets in the air line as it will short out the element, we used turbine air for the shop air or gas. Do you have a tacking and a speed tip? The speed tip is the one shown on mine. They are used different for welding, and there are various other kind too.
Paul

ps: There is also some youtube videos of the welding being shown.

 

[randyjaco]

No, mine doesn't have a speed tip. It came with the tips shown in the HF ad I posted originally. That speed tip looks like it might be useful but I don't know where I could get one to fit mine.

One thing I am finding out is that my welder with the built in blower gets heavy quick 8^(

Randy

 

[pjf134]

Randy,
The vid from HF seems like they are using too much heat, unless that is some kind of new rod on the market. Type in plastic welding and see some of the youtube vids and see the way they do it is the way it should be done without the speed tip. The HF gun looks to be too bulky to work with for me at least. My speed tip screws in the same way the HF one does, so maybe you can find one to fit yours. The speed tip is easy to use I think. Four things to work on are correct temp., pressure, angle and speed.
Paul