Plastic Welding Question

[chicken]

I picked up a Laramy Plastic Welder to do some work on the Sulfur and other reactors I am building. I am looking for some advise though on what size welding rod I should do and should I use round or triangle rod? This will be for welding sheet PVC to acrylic tubing. Thanks!

 

[CMcNeil]

if you are welding thin acrylic tube(1/8" thick)you should use no larger than 5/32 round rod.larger thickness tubes would be able to handle .236 triangle.
i would say in most cases you will want 5/32 round max.BTW i am a plastics welder by trade so this is all first hand knowledge.
whatever you do make sure to practice alot before making your reactors or whatever.the 5/32 rod can get soft real fast and not flow correctly if you have the temp or weldrate off.

 

[chicken]

Thanks for the info!! What temp and PSI should I be shooting for with the 5/32" rod?

Thanks

 

[chicken]

its 1/8" acrylic tube and 1/4" PVC sheet BTW. Thanks!

 

[dattack]

I hope you tubing is cast, otherwise the heat from the welder will probably craze and later crack the tubing.

 

[chicken]

yah its cell cast, I refuse to use extruded for anything. Just not worth the hassle. Thanks

 

[CMcNeil]

here is a chart from wegener plastics that has alot of info
you should be welding at approx 610-700 degrees F
air flow should be approx 1.4-2.1 CFM

http://www.wegenerwelding.com/usa/flash/pdf/WW_Guidelines_2005_2.pdf

 

[mavgi]

<a href=showthread.php?s=&postid=12878516#post12878516 target=_blank>Originally posted</a> by CMcNeil
here is a chart from wegener plastics that has alot of info
you should be welding at approx 610-700 degrees F
air flow should be approx 1.4-2.1 CFM

http://www.wegenerwelding.com/usa/flash/pdf/WW_Guidelines_2005_2.pdf

from your experience is those type can do the work to ?

http://www.arizonatools.com/tools/plastic-welders-rods-and-plastic-adhesives/detail/UREATVPRO/

i will need to glue 3/8" , 1/4" thick

from what i read , nitrogen is best & the inert gas flushes out moisture and prevents oxidation from forming during the weld.
but i need it maybe for one time and don't want to invest on the expensive ones

 

[CMcNeil]

i have never used that welder before.from what i am seeing that welder doesnt have an air supply(or need one)kind of like a hot glue gun.the welder i use has a blower motor to feed fresh(clean oil-free air)to my welding gun.nitrogen isnt needed for welding unless oxidation is an issue.we only use nitrogen gas when welding plastics like Halar or Kynar.for all other plastics(PVC,PP,LDPE,HDPE,CPVC,ABS) we only use the oil free air blower.

 

[mavgi]

Thank you for the replay .

i will give it a try since i don't need it for big project maybe it will be good .

 

[SunnyWindyClown]

what plastic rod would you use for acrylic to pvc bond? i want to try to make a skimmer.

 

[CMcNeil]

pvc rod works fine for that bond

 

[SunnyWindyClown]

thanks i will try it.

 

[alpine]

Hey Chris what brand & model of welder do you use? I spoke with you on another thread when you were building your cone skimmer.Well I am no longer at the motorcycle shop I worked at.The new shop I work at uses duramix for all there fairing repairs.

Unfortuenately I never knew what model welder we used at the old shop,since the welder was very old and no longer had any markings on it.It was a piece of junk anyway and made repairs longer imo.Thats probaly the reason why I could never get such a good weld as the ones you make.

Anyway,for others and myself.What brand and model of welder would you suggest for the hobbiest?I do a lot of side work on bikes,and it would be nice to do some welding on some reactors and a future skimmer build that I am doing.

TIA

 

[CMcNeil]

here is the welder i use at work(model duratherm)
http://www.wegenerwelding.com/usa/flash/index.html
these welders are not hobbiest types and can cost well over $1000(without the blower),but they are like the mercedes benz of plastics welders.
for the average hobby guy i think something like a kamweld is good.
http://www.kamweld.com/CatProducts.asp?Catid=1

 

[H20ENG]

CMcNeil,
I have done a fair amount of plastic welding, mostly pvc and abs. (a self contained Laramy)

I have often wondered how much strength is added with a weld bead of pvc to acrylic, over and above the glued joint.

I also dont like the joining of 2 dissimilar materials. Even on high dollar skimmers and such, you can see the burnt acrylic at the edge of the weld.

I guess I'm just not convinced its worth the effort, and would like to hear your opinion, as you have been around the plastics business. Love your projects, BTW

Chicken,
I actually made a cheapo HF air welder work by using a lighting dimmer for the heating element. Much better control that way. If I were using one every day, the Laramy or Wegner would be my choice.

It takes a fair amount of practice, especially when trying to make a good pvc to acrylic bond. Love your projects too, BTW! I hope my shop grows up to be just like yours someday!:lol:

 

[CMcNeil]

H2OENG......i would have to say that IMO the overall strength isnt any greater with the weld VS glueing(i believe it is theoreticly weaker welded than glued).once you heat the plastic up to the temps required to melt the welding rod,tech you weaken it.that being said,i still prefer a stick weld on anything i make that is externally run over a glue joint.i have made several reactors and such that i glued.i have had some leaks,all of the stuff i welded NEVER leaked.the burnt edge you see on the weld is probably just oxidation(or old material,or just a dirty weld from lack of cleaning the tip).if you were to weld it using nitrogen instead of air that shouldnt occur.also sometimes a glue joint just isnt practical for the application and a weld works better.

 

[H20ENG]

Thanks. I think the dirty welds I've seen (made a few myself!) have simply been from overheating.

I also think that the acrylic gets too hot when welding, creating an un-needed stress point.

I agree that sometimes only a weld would do. I have repaired many a broken pvc line where we did not have the right fitting on hand, so you either build one or weld the heck out of it.

I once had to fab an internal coupling for a 6" pipe, that broke off as it stubbed out of the concrete floor.

Then, the time when the 4" raw seawater line broke right over the moving walkway control panel on the Friday before vacation. Joy... Who brought up plastic welding anyway?!!

 

[CMcNeil]

ohhhhh... if you only saw some of the things people have asked me to repair over the years,its plain comical at times.one time we had to go out to a water treatment plant being built.all of the lines were containment lines(two lines,one inside the other)some moron installer forgot to glue EVERY fitting in the outer containment lines.well that isnt gonna work obv,so we had to go backweld every joint,BTW it was summer in florida and we were 8' underground in a pit lolol.......fun times.....