Plastic Welding Part 4

Yes the weld is not as strong as if it was new. I ground it thin and any piece that flexes that much in normal use will just have to be replaced. Also when I am welding in front of the camera I am trying to hurry to keep the clip short. Pieces welded at leisure tend to be somewhat stronger. Any event that flexes a piece of motor cycle plastic this much is called a crash and guess what, even a new piece would break.

Category:

Autos & Vehicles

Tags:

• Plastic
• Welding

[rgpark69]

can you use it like caulk or rtv silicone to pach aluminum or magnesium cracks or Piercing in an oil pan?

[rheniformer]

I do not think it would be very good as caulk at all. It is very hard and I do not think it would bond very well at all to aluminum which would sink the heat away from the filler rod very quickly. I was given some green rods that would probably work, they were made to seal pipe. Thank you for your comment

[glyph000]

You don't say why you start in the middle rather than at one edge.

Why in the middle?

[rheniformer]

I found that when I started in the middle that my edges were stronger. The plastic that I was practicing to weld is quite thin (Sport Motorcycle fairing) so distortion was a real concern. By carrying the weld past and back at the edges there was more material for trimming and required variably no body filler at the edges. On trials where I tried to start at the edge, when I directed my heat at the edge, as soon as it began to melt the parent material would shrink back distorting the edge.

[LeMieux250]

It'd probably be a bit stronger if the base matierial got a little hotter. Nice job though!

[rheniformer]

I dumped my bike, bought a welder from ebay (it was only $70new) and made up my own method which I posted because I couldn't find any clips using a hot air welder on similar thin motorbike plastic. The ones I did find looked like my earlier attempts which were very weak. I would love to find other clips where a sample of motorbike fairing is stressed to failure. Not to be competitive but because I would readily adopt a stronger method. Thank you for your comments I appreciate the discussion.

[rheniformer]

@glyph000 It's not obvious on the clip but the very surface of the black is melting. The reason I keep dobbing the white rod is to insure that the surface of the black is tacky. The black was so thin that it would easily heat through and sag. I tried supporting the black and melting it more but the weld became very week. I see others using a universal rod that is black and flat it is actually an adhesive like hot glue but better, I have never thied these.

[glyph000]

You are melting the white rod but not the black. You must soften the repair piece (black) so that when you melt the white rod they will "bond" together. If you don't soften both equally you get a break like your test shows: right at the weld point.

If you heat the black pieces more, you will get a stronger joint. The best way is to start by putting the white rod in and pulling it out. You should pull up some of the melted black as well as the melted white. If not both you're not hot enough.

[rheniformer]

You're right I would say a mechanical bond, a fairly good one. I repaired my bike about a year ago and it's still good. Tried using a strip of material cut from weld subject, it was no better. I welded some white ABS, it appeared to take much better hold but since it was a repair for someone else I did not have an opportunity to test it, it as well is still good after a year. Others I have talked to have had welds fail after use and vibration which mine have not so overall relative success.

[wildweston]

Nice series; judging by the way that plastic broke you are not fusing with the subject plastic. The strength it had was in a mechanical bond. When you get fusion you won't see the subject plastic breaking freely away from the weld. Good luck!