Plastic Welding

[CyberianHusky]

Has anyone ever tried one of those Plastic Welding kits from HF???

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=41592

I figured if there was ever someone who had, they would be on here! It seemed like a good idea, and besides it was ON SALE!:)
But......I haven't tried to use it yet.

Maybe Hobart should make a plastic welder....cause there's an awful lot of it around us!

Back to work...

Don

[Hobart Expert Rock]

HI DON.....ACTUALLY PLASTIC WELDING HAS BEEN OUT FOR A LONG TIME......I REMEMBER SEEING IT AT THE WELDING SHOW IN CHICAGO MANY MOONS AGO.......LOOKED AT IT BUT AS I RECALL THERE WASN'T MUCH MARGIN INVOLVED.........YOU KNOW HOW BEEN COUNTERS ARE IF NOT ENOUGH INCOME FOR THE BOTTOM LINE THEN IT'S JUST NOT POSSABLE............. GOOD THOUGHT THOUGH.............ROCK............. SSCOTT@MILLERWELDS.COM

[Mike Sherman]

Don, I have never used a plastic welder, but I have seen it used before. I used to weld and repair a Pickle Line which used Hydrochloric acid and alot of the partitions and stuff were custom made out of plastic that was welded together. What would you use it on??

[CyberianHusky]

Originally posted by Mike Sherman
Don, I have never used a plastic welder, but I have seen it used before. I used to weld and repair a Pickle Line which used Hydrochloric acid and alot of the partitions and stuff were custom made out of plastic that was welded together. What would you use it on??

Mike,

I bought it with the intention of using to fix old car interior parts. Now I know that just like you have different welding rods for different metals, there's different rods for different types of plastic. I purchased the extra plastic rods, and figured one day, I'd try it out.

For example, I have a plastic grill that needs the plastic mounting tabs "Welded" back on. I figured it was worth a try, just wondered if there was someone here who had already tried it.

As much plastic as we have in our daily lives, it would be nice to fix some of it, rather than throw it away.

Don:)

[Rocky D]

We do quite a bit of PVC welding here at my plant. When done right, the weld are just as strong as the parent material. One difference is that you scrape your weld joint to make it ready to accept the hot plastic. (Scrape, as opposed to grind or sand it)

Since you have one already, do some welding and tell us how it turned out.

[CyberianHusky]

Well, I started this thread a LONG time ago....LOL and I tried that plastic welder last night. I was trying to weld a plastic Toyota taillight housing. But the problem was none of the three types of plastic welding rods would work with the light housing.

The light housing plastic would melt much quicker than any of the plastic rods.

I'm not sure how you identify which plastic type you're working with.

Am I assuming too much, or should compatible plastic welding rods melt at the same temperature as the work plastic?

Any ideas anyone?

I finally just used a rod to make the original plastic just melt together. While it wasn't a good fix, it was better than nothing.

Thanks, Don

[jason]

Don, I've done a bit of plastic welding so I'll tell you what I know.

Plastic:
1. The filler has to match the work - or it wont work.
2. Some plastics don't weld well anyway, or require the use of prep agents.
3. The best way I know to determine the base material is the recycling number molded into the part, unfortunately this is only found on newer parts. The number inside the little triangular recycle logo corresponds to types of plastic.

Welder:
I have one of those HF welders and in my opinion its a real good value except for one thing, it doesn't come with any tips. Iv'e used a similar (much more expensive) welder that had tips that contacted the plastic that worked real well, I just can't get the thing to work using the hot air alone. MSC has tips, but they're like $75 ea.

I'll try to dig up some more information for you.

Jason

[jason]

Don, alot of good information here:
http://www.urethanesupply.com

Jason

[Terry Lingle]

I have done some plastic welding 20-30 years ago what I remember is the rod must match the parent plastic.
To test for weldability in an unknown plastic part heat it in a non critical area and see how it reacts. Often on unknown weldable plastic you can cut a rod from a non critical place on the piece
to make your repair Terry

[Jerry]

I too have done a little of plastic welding long time ago but never really got good with it. I do remember the unit we had used compressed air and I think electric ? well anyhow, if the air pressure was to much it would work terrible. I think pressure of around 2 or 3 lbs. was a good fit

The millwright started doing and got pretty good so boss always gave it to him, lucky me.

[jerry_tig]

Plastic welding can be done with an hot air gun and the right type of tip.

Not all plastics can be welded. Most interior car parts are polystyrene, which glues better than it welds (with the right glue).

If you do not have a recycling number, you can determine the type of plastic by burning a part of it and looking at the flame. If you don't get the information on the shape and color of the flame and smoke from the plastic rod supplier, simply burn a few different rods and look. Don't breathe the smoke.

[Rocky D]

Originally posted by jerry_tig
Plastic welding can be done with an hot air gun and the right type of tip.

Not all plastics can be welded. Most interior car parts are polystyrene, which glues better than it welds (with the right glue).

If you do not have a recycling number, you can determine the type of plastic by burning a part of it and looking at the flame. If you don't get the information on the shape and color of the flame and smoke from the plastic rod supplier, simply burn a few different rods and look. Don't breathe the smoke.

So, jerry are you saying to match the flame color to determine the type of plastic? and or rod to use to weld the plastic?

Can you actually see the "fusion" when welding the plastic with your hot air torch?

[jerry_tig]

>>So, jerry are you saying to match the flame color to determine the type of plastic? and or rod to use to weld the plastic?

Somewhat. I am saying that different plastics burn differently. PVC, for example has acrid smoke and flaming drops. Polypropylene, if I remember correctly, burns with a black smoke. Etc, etc... The maker of the plastic rods should be able to give you the correct information, and, as pointed out, you can always burn a little bit of rod and see for yourself.




>>Can you actually see the "fusion" when welding the plastic with your hot air torch?

You need a special nozzle for the gun, with an opening to fit the rod into. Then, you don't see much, because it happens in the nozzle. And the plastic never goes really fluid, it behaves more like mollases or chewing gum.

[Rocky D]

Thanks for the info , Jerry, while I've seen it being done, I never really studied it.

[ampdog]

Originally posted by jason
Don, alot of good information here:
http://www.urethanesupply.com

Jason

I have the model listed at this link;
http://www.urethanesupply.com/5500HT_info.html

It is different from Don's in that it's airless. It comes with a video and a good assortment on welding rods and tips (plus a catalog with an even larger assortment of rods and tips). Including a universal rod that is supposed to bond with most everything. I haven't used that particular rod yet, I'm doing Motorcycle fairings so I have been sticking with the ABS rod with good results. The video is very good and does a great job of teaching you to ID plastics. They did a pretty good job of that in the literature that came with it also.

[CyberianHusky]

The LIMITED instructions that came with the HF unit said use 3-4 PSI of air for the process. For my particular application, that was too much for the base plastic.

It looked like if I had a similiar rod of material, I could have made a decent repair. As it was, just forming the original plastic helped, once it was heated.

Based on the replies I've seen here, I don't know how practical the HF unit will be, but maybe it could be used for warming up plastic for shaping purposes.

And there wasn't ANY information with the HF rods I purchased.

[ampdog]

FYI, incase you need to again......

This link is to the Rods I mentioned before, they are supposed to be usable with most any plastic "Fiberflex".

Flat
http://urethanesupply.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=URE&Product_Code=5003R10

Round
http://urethanesupply.com/Merchant2/merchant.mv?Screen=PROD&Store_Code=URE&Product_Code=5003R11