Automotive Air Conditioning pipe welding - advice and help please

[bc30se]

Hello...

I am going to buy a new machine and extend my range of service... I would like to do AC pipe welding in automotive branch


I have found the machine which I would like to buy... this one

http://allegro.pl/spawarka-welder-fantasy-jet-tig-ac-dc-200-raty-i3051612100.html

It is (again) Chinese manufacture but not my first machine form this particular dealer and I am sure i will be happy...


the only question, I am not sure if the lowest setting for the AC current - 20 amp will do the job, or perhaps it is just too much???

 

[hotrodder]

20A should be low enough although it depends on how thin wall the smaller dia aircon pipework gets. Be aware that small dia thin wall ally tube is about as difficult as difficult gets when the result has to hold pressure and not be blocked by a weld that's sagged/has excess pen... JIC -4 hardline is about as small/thin wall that i have to weld regularly, 6.35mm OD, ~0.8mm wall and thankfully it's usually fillet welding it to something bigger/thicker like 1.5mm sheet ally as butt welding two pieces that size has no margin for error

 

[bc30se]

It can be also done (I myself had it done once on my car long time ago) with an overlap joint, the guy simply placed a tube of a bigger size over the cracked one and did an overlap. Worked great, and definitely easier to weld....

I can also choose a different machine, that goes as low as 10amps for the AC but the duty cycle is worse....

200amps - 40% and the one I showed is 200amps - 60%, except for these, they are both the same...

http://allegro.pl/spawarka-digitec-tig-digitig-205-p-ac-dc-sherman-i3081552815.html

 

[Shox Dr]

^^ second that. Repaired an aircon pipe for someone a while back. 9yr oldcar, part not available any more, and when it was it cost 178quid.

 

[bc30se]

^^ second that. Repaired an aircon pipe for someone a while back. 9yr oldcar, part not available any more, and when it was it cost 178quid.

is 20 amp low enough?

 

[Shox Dr]

As HR says, it should be. (Insert disclaimer). What's it's lowest on DC

While I'd say its abithigh for some of the stuff I've had to weld, a pedal makes a world of difference

Edit just looked 5amp.

 

[bc30se]

5amps for DC and 20amps for AC, guys I don't need to weld cola cans just to show off, if I am ok with 20 amps (I can still use balance settings) to weld AC pipes, then it's good for me...

how thick is the ac pipe, 0.5mm I believe...


the second one I showed... there must always be some problems like the one has something the other does not...

I was to go for the second one - 10amp for AC and a little bit cheaper, but no pedal option

 

[chevy2]

Apparently to hot ticket for welding ali ac pipes is the lumiweld type thing or whatever its called? its a kind of solder rod applied with a blowlamp,
a mate of mine whos a mechanic swears by it, repaired several ac pipes with it, and for the record he also tig welds and prefers this way,not cheap at about ten or twenty quid for a 1m length?
the guy was at the ally pally engineering show.
think the guy is from europe? and attends a lot of uk shows

 

[snowcat]

Al A/C Pipes are very hard to weld effectively, Firstly you have the material thickness, then you have the exterior corrosion, then you have the internal oils, which will then be inpregnated into into any leak.

If that wasn't enough of an issue, given time and the pipes will become porous, especially to R134a which has a very small molecular size.

I have years ago managed to repair the odd pipe or condenser, however now there are far better ways of preforming repairs, (lockring, bubble crimp) are two that spring to mind.. replacing is often the best method TBH repairs nearly always leek, and removing, repairing, refitting, pressure testing, vacing gassing/oiling, only to be back a week later doing the same job is simply not cost effective.

 

[eil]

There seems to be a bit of a push on alu tubing in the fridge / Ac industry recently to use less copper, I was given some by a rep to try out with a suitable brazing / soldering rod, takes a bit of practise but it quite easy to use. Don't know how it would work on a system that has been in use though as I haven't needed to try it out yet.
http://www.youtube.com/watch?v=HqgV3URZTb0

 

[hotrodder]

Lumiweld (also Durafix and a bunch of others) are all just a self fluxing zinc based solder and are typically a bunch cheaper from a proper welding suppliers than from the shills that hype the stuff to be something it isn't for example...

Lumiweld on ebay, 10 (9" long!) rods + a stainless steel wire brush for £18 + delivery
Durafix £24 for a pack of 5 rods
Technoweld, £25.95 for a 10 pack (200mm long)

or without the hype... http://www.rapidwelding.com/dynamic/DisplayItem.aspx?c=RO5532XX SIF 555 Al solder £21.88 for a pack of 12. The SIF stuff is 93% Zn, 4% Al and 3% Cu

Some more flavours of the same/similar stuff... http://www.brazing.com/Pdf/Aluminum%20Data%20Sheets/ALU-ZINC.pdf, http://www.esabna.com/EUWeb/AS_handbook/596as7_8.htm and the Johnson Matthey version which is slightly different with a slightly higher melting temp... http://www.jm-metaljoining.com/pdfs-products/Alu-Flo%20ZA%20-1%20ChannelFlux.pdf

Any of 'em fine, well ideal, for this sort of thing especially if used for capillary joints as per the vid posted. Now if only the shills would stop hyping it up as welding/better than traditional welding techniques/stronger than welding (it is stronger than many flavours of ally, it's also brittle...

 

[bc30se]

guys.... as usually you are most helpful


I should have just asked if I could do 0.5 mm thick aluminium with this 20amp... would be much easier....


otherwise, great info on ac pipe tricks