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ArthurQuote:
Originally Posted by wrinklearthur
Sikaflex is an air cure permanent polyurethane bond, its what they stick some cars and aeroplanes together with, but yes the surfaces need to be cleaned of paint layers otherwise the Sikaflex will bond permanently to the paint but not the aluminium underneath. A wire wheel is sufficient to prepare the surfaces for bonding.
The automotive adhesives/sealants are Sikaflex 227 and 255 Extra+
I think mike ( series one buff). Had used/ try'd or had info on the mock spot weld technique .... Or I have it in a magazine... Ill look today authur
Re the welding there's a low temp alloy welding system that was talked about by incisor and others a while ago ... Uses primus type temps lower than alloys melting and distortion point dura something
....Duraweld Australia on google....
I've never used the low temperature alloy brazing/soldering system. There always used to be someone at an autojumble (swap meet) in the UK repairing a thermostat housing as a demo.Quote:
Originally Posted by mfc
I purchased some, was never confident with using it then my Father-in-Law gave me a heap of it, he too wasn't really convinced.
Something like this Dura Fix Aluminum Welding Aluminum Brazing Aluminum Soldering & Repair Rod is not sold on Ebay US or Amazon
From memory you melted a puddle of it onto the piece you're repairing then with a st/st wire through the molten puddle you scratched off the surface oxidation and hopefully it bonded.
I haven't spot welded aluminium but it was interesting when I asked a couple of customers who have spot welders recently they weren't interested in trying to spot weld aluminium. I'm guessing it's not quite as simple as steel.
A TIG to weld aluminium is expensive (even the cheap ones) because you need HF start.
I'm considering an oxy set and lots of practice.......
Colin
Spot-welding aluminium requires a very large capacity welder (3-phase), which limits most of us from ever trying :(
Sikaflex works superbly and will not let go! Even Rover's spot-welds let go sometimes.
An alternative to a spot-weld, is to do a plug-weld using a TIG, which can look a bit like the real thing but control of panel distortion needs to be considered,
Cheers Charlie
Anyone considering using Sikaflex polyurethane adhesives should be aware that you will likely only get one go with the tube. Most often the remains will cure inside the tube even in a short period and certainly overnight.
The rule of thumb is collect all the prepared jobs together ready for a single session. Use disposable gloves changing frequently when contaminated, have plenty of lint-free disposable rags available (and a bin) and maybe get all your mates together with their Sikaflex jobs.
As Arthur suggests (below) it is important that the surfaces to be joined are dry, don't do the job on rainy days or early in the morning while dew is still on the ground.
I happen to have a 'pie heater' three phase AC welder and was under the impression that a suitable spot welder for welding aluminium was a large current low DC voltage device.Quote:
Originally Posted by chazza
I have spent more time than I care to think about, removing Sikaflex when confronted with the stuff on fishing boats when I was installing satellite telephones, it sticks like anything in some spots, but then moisture will find it's way inbetween the Sikaflex and the Aluminium and it will then wick it's way right along a jointQuote:
Sikaflex works superbly and will not let go! Even Rover's spot-welds let go sometimes.
Hi CharlieQuote:
An alternative to a spot-weld, is to do a plug-weld using a TIG, which can look a bit like the real thing but control of panel distortion needs to be considered
With that three phase welder I have, it's possible to adapt a TIG welder handset to it, but I believe for Aluminium the welding voltage needs to be DC.
.
Thanks DianaQuote:
Originally Posted by Lotz-A-Landies
I have thrown out unused unopened tubes that I had ready for a job -$$$$$ , the unopened tube had gone off in the time I had it waiting :mad:.
So when preparing for a job, get ready first, then go to buy only what is needed and keep your receipt as the shelf life of the stuff starts in the warehouse and not just when you get it home.
.
This info followed a link on 'Show us your Deefers !'.
Sheet Plate | Aluminium Warehouse
ph: (02) 9907 2222
2 Wattle Rd, Cnr Harbord Rd, Brookvale NSW 2100
© Copyright Aluminium Warehouse
website by fazedesigns
You also need High Frequency start, you cannot scratch start the arc with TIG (so I'm told).Quote:
Originally Posted by wrinklearthur
A cheap Chinese TIG for aluminium is around $1K.
I'm told they either work OK or fail quickly. So you might go through a few to get a good one !!!
Resistance welding handbook here :-
http://au.search.yahoo.com/r/_ylt=A0...Resistance.pdf
Seems that it's the high current needed to spot weld aluminium (compared to mild steel) that is the issue.
Colin
now im certain ive seen an article or youtube video where a tig welder was used with a brass block behind to replicate spot welds......
ive got vibration cracks on the firewall edge of my front wings{loose bolts n strut i recon} ime toying with silkaflexing a folded stiffening plate behind and clamping without riverting it.....im not shure of the durability of durawld rods and the new metal old metal causing the old to fail{as mentioned by dianna above}
perhaps duraweld{ durafix not duraweld } then reinforce w silkaflex