Welding plastic

[blacktruck]

Yea. I have a little experimenting to do for sure. I have a lot of experience working with composite materials that all accept the addition of some sort of an adhesive and filler material. I would have given that a go but was told as mentioned above that most adhesives won't stick to it. I am looking forward to trying this when I get home.

 

[yomax4]

I've used the sub $20 soldering iron plastic welder from HFT and it works fine, do NOT press as the copper tip will break at the 6mm threads going into the iron when hot... but I've successfully ran a die down it and it lived again... it comes with some stainless screen material which you can bury in the plastic and help out.

The SS screen sounds like a great idea. Adding it to my plastic welding box.

 

[jwmorris]

As far as filler, assuming I don't know what the parent material is, I try and remove enough of it from the part (from an unseen location) to use as the filler. Will not only be a material match but color as well.

 

[yomax4]

As far as filler, assuming I don't know what the parent material is, I try and remove enough of it from the part (from an unseen location) to use as the filler. Will not only be a material match but color as well.

When I 1st got interested I visited a motorcycle junk yard. They gladly let me pick up pieces of assorted colored plastics. I still have some. There is a burn test as well to determine types but it's not that accurate. A couple are easy to determine but many others burn similar.

 

[AnotherBueller]

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 been using the Polyvance 5700HT welder, which is an iron type, for awhile and it is a welder. You preheat and melt the base plastic then melt the right filler plastic into the SMALL grove between the two pieces, just like stick welding. Do the repair on the back side. I like to add the SS screen to the back when I'm done and melt it into the repair with the iron and smooth out by holding the iron just above the join and later the screen until all the plastic has the same color before I let it cool. If you can weld metal you can do plastic. Just slightly different technique.

 

[mrmikey]

Squirrels ate thru a corner 'bout the size of a dime thru the fuel tank on the SIL Craftsman snowblower and there was none available. I used a strip of plastic cut off the rim of a 5 gallon bucket for filler. While not easy it was doable, the melted plastic has absolutely no surface tension, get it one degree past the melting point and it would fall thru.

 

[blacktruck]

I will definitely have a learning curve to get past. With more and more of the bodywork and accessories being made of plastic anymore, it seems like the information about the content or type of plastic used should be easier to find. I pride myself on not scuffing or banging up my equipment and a one project deal at my SIL's garage left me with a fairly gaping hole in a fender. I'm certain that I am not the only one to have this happen. I am retiring soon and it is time to learn about this. I am certain that I can make it stick together, I am mostly concerned about finding filler material for the missing pieces. I probably have an area of 2"X3" missing. Fortunately it is in a flat area. I'm not concerned about a color match, just compatibility. I appreciate all the replies. Keep them up. I will be getting into welding metal also when I get back so there will be questions.

 

[yomax4]

Might also read up on some of the new adhesives out there. Many plastic welding applications were killed off due to super advanced adhesives for the auto industry.

 

[jwmorris]

There is a burn test as well to determine types but it's not that accurate.

There are specific gravity tests with water that I use from time to time.

 

[Mark @ Everlast]

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. But they were a much different material than the current plastics you would find on a tractor fender. 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. This happens a good bit and they know how to fix stuff at the mfgr level I'm sure.