Welding plastic

[pmsmechanic]

I have a 200w amazon kit Amazon.com
Repaired a large in ground valve box that had been split and discarded when run over by a truck. Worked good. Looks like getting nice finished results might take some serious practice, sanding, painting, etc.
I used paperclips for stitches. Simply push them into the material across the break with the hot iron then weld over them.
My plan is to repair a leak in a 4k gallon water tank.

I've used paper clips as well. The ones with scored edges work better than the totally smooth type. I tried welding a water tank. It worked but then went and cracked in a different spot with the next load of water. I'm thinking the sun degraded the plastic.

 

[ArlyA]

I'd guess products made to be used outdoor like a water tank would be UV stabilized. Black polyethylene that's not UV stabilized is still pretty long lasting that's why I use it.

 

[scootr]

I've used paper clips as well. The ones with scored edges work better than the totally smooth type. I tried welding a water tank. It worked but then went and cracked in a different spot with the next load of water. I'm thinking the sun degraded the plastic.

This green poly tank is about 20 yrs old and the crack appeared in the lower section... I plan on giving it a go. Figured I have little to loose at this point. I already replaced it so the second tank would just be a holding tank with fire crew access if needed.

 

[blacktruck]

A lot of "plastic" fenders on tractors have a fiberglass or some other fiber component to them. Very rarely are they a plastic that could be welded back together. I was working for New holland when they introduced Plastic fuel tanks on their Genesis tractors and some of them were getting holes in the tops from something rubbing or puncturing them (can't remember what exactly) but they gave us welding instructions which satisfactorily repaired the tanks and stored the structure. I'd suggest an epoxy or fiberglass repair first, or contact the company to find out what type of plastic it is and if it is indeed repairable. I'd bypass the local dealer if they start with a sales pitch on a new fender.

I know the technology has changed a lot over the past few years on composite materials. This tractor is a 2009 model so it is a few years behind where we are today. I did a close look at a piece that was severed from the fender, I didn't see any fibrous materials. It looks, feels and acts like a type of plastic. I'll find an inconspicuous area to try. I do want to attempt a glue and filler solution first and see if it will bond with the "plastic". If that doesn't work, I am all for welding or melting in a piece. My ultimate plan would be to paint it so finding a filler and subsequently a paint to stick is important.

 

[scootr]

I know the technology has changed a lot over the past few years on composite materials. This tractor is a 2009 model so it is a few years behind where we are today. I did a close look at a piece that was severed from the fender, I didn't see any fibrous materials. It looks, feels and acts like a type of plastic. I'll find an inconspicuous area to try. I do want to attempt a glue and filler solution first and see if it will bond with the "plastic". If that doesn't work, I am all for welding or melting in a piece. My ultimate plan would be to paint it so finding a filler and subsequently a paint to stick is important.

Do your plastic welding on the underside. Most plastic welding kits include fine screen material for structural repairs like this. Then do your cosmetic repairs on the top side. My experience is buy the highest wattage welder you can afford for the best results. https://www.amazon.com/gp/product/B00U1IO5DY/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1