Tig welding alloy wheels

[Richard.]

I will weld many things on a car, but anything critical to the handling of the vehicle, ie brakes, steering, wheels etc get replaced instead, it's just not worth it

I wouldn't worry too much about how critical the component is with regard to what it has to do because some of these items are made out of materials that is very weldable and if repaired correctly will be safe and strong. It's when a material has been subject to certain treatments/manufacturing processes to aid with its design/strength/ductility etc and welding will change these properties then I approach with caution. Im not too worried about what the item has to do as I am about how I'll change its ability to do it after repair.

 

[Tinbasherdan]

I wouldn't worry too much about how critical the component is with regard to what it has to do because some of these items are made out of materials that is very weldable and if repaired correctly will be safe and strong. It's when a material has been subject to certain treatments/manufacturing processes to aid with its design/strength/ductility etc and welding will change these properties then I approach with caution. Im not too worried about what the item has to do as I am about how I'll change its ability to do it after repair.

Oh I don't doubt I could weld most of the components, I just refuse to!

 

[Richard.]

Oh I don't doubt I could weld most of the components, I just refuse to!

Which there is nothing wrong with doing. I've got an expensive mountain bike frame in at the mo that has cracked. its 7*** series I believe. Someone has already (badly) had a go at it so things have already been altered regarding its strength. I'm going to repair it with a re weld but I'm also going to add a guset in the corner to Aid with strength and take some pressure off the welded area. I don't think it will be as good as it once was but at least with this type of job I can use design Improvement to help as an advantage.

 

[normspanners]

The favourite used to be split rims on jcb wheels

Trucks used to be spit ring like that with abig circlip holding the outer rim on i have done loads of those and the safest things is your eyes and a lump hammer to keep knocking the rim and clip to make sure it seats
A guy I knew was removing some true split rims (bolt together) crane tyres, in 2011 (he should have known better) and removed not only the wheel studs but some of the wheel rim clamping bolts, you have 12-20 ton of force trying to get the wheel apart unfortunately he is not here to explain his mistake and died of massive internal injuries now his boss has been fined. All very sad.

 

[Tinbasherdan]

Trucks used to be spit ring like that with abig circlip holding the outer rim on i have done loads of those and the safest things is your eyes and a lump hammer to keep knocking the rim and clip to make sure it seats
A guy I knew was removing some true split rims (bolt together) crane tyres, in 2011 (he should have known better) and removed not only the wheel studs but some of the wheel rim clamping bolts, you have 12-20 ton of force trying to get the wheel apart unfortunately he is not here to explain his mistake and died of massive internal injuries now his boss has been fined. All very sad.

I did mean split rings! Sodding auto correct :/

 

[PhillipM]

Hell, I weld all sorts of critical steering/suspension/brake components up - the racer is made of welds held together with scrap in between - but I don't weld cracked alloys. Ever.

 

[hotrodder]

Rather than suggesting such repair isnt a feasible option, would it not be more productive to look at the best possible way of carrying them out?

Laser welding was briefly mentioned in one of the links i posted. Not exactly helpful for DIYers but that sort of thing is the only way to reduce the HAZ over the results you get with MIG or TIG
A 5xxx series filler wire has been mentioned in this thread and by someone claiming to be a wheel specialist in one of the other threads on the subject. Metallurgically that's just wrong for an alloy that WILL be high in silicon to aide the casting process but assuming a perfect weld (no such thing) the HAZ will still be the weak link usually. Beyond that it's a craps shoot... keep the heat input as low as possible to minimise the HAZ and role the dice, the repair may last a long time or it might crack again quickly because the wheel was cast from a less weldable AlSiCu allloy instead of a more weldable AlSiMg flavour. Either through the repair if the welder didn't know what they doing, through the HAZ which'll still be their fault but down to pot luck as much as anything or it might be a fresh crack that wasn't visible to the naked eye because if you start doing some proper NDT the repair bill goes up and a new wheel often starts making more sense. If your business is refinishing wheels there's more of a finiancial incentive to take on repairs instead of sending the punter away to buy a new wheel...

If the fad for massive wheels with rubber bands for tyres, especially run flat rubber bands, died out wheels would be far less prone to cracking. If the fad continues it will probably get worse as manufacturers start taking weight reduction for economy/the environment more seriously. I hope i'm wrong but lighter wheels that are more reliant on heat treatments and/or grain structure from flowforming are gonna be less forgiving when repaired i.e. instead of a crack growing slowly resulting in a slow puncture things are gonna happen more quickly when fatigue takes over. Let's not forget that aluminium has no endurance/fatigue limit unlike steels or titanium etc

 

[Wozzaaah]

^ Unfortunately the fad is showing no signs of slowing, rim diameters and tyre widths are still increasing which means sidewall profiles are getting lower.
Years ago 60 or 55 profile used to be the norm for a "low-profile" tyre but 40 and 45 are now becoming the norm and we're starting to see more and more 35 and 30 too on the very wide ones.
Tread depths are diminishing too, all to do with increasing the energy efficiency.

 

[hotrodder]

Yeah, the increasing width is the one i really don't get (modern cars are so big/slab sided sensible dia wheels tend to look like castors). Most cars have far wider tyres than they need, usually that reduces economy but maybe that's offset by the higher tyre pressures often recommended (presumably to help CO2 emissions when setting tax classes etc) these days? A bit narrower would probably help, at least with the more common cracks on the inner rim lip. Might also help reduce the gridlock that follows a light dusting of snow every couple of years

 

[Chris Stevens]

7 series materi

Laser welding was briefly mentioned in one of the links i posted. Not exactly helpful for DIYers but that sort of thing is the only way to reduce the HAZ over the results you get with MIG or TIG
A 5xxx series filler wire has been mentioned in this thread and by someone claiming to be a wheel specialist in one of the other threads on the subject. Metallurgically that's just wrong for an alloy that WILL be high in silicon to aide the casting process but assuming a perfect weld (no such thing) the HAZ will still be the weak link usually. Beyond that it's a craps shoot... keep the heat input as low as possible to minimise the HAZ and role the dice, the repair may last a long time or it might crack again quickly because the wheel was cast from a less weldable AlSiCu allloy instead of a more weldable AlSiMg flavour. Either through the repair if the welder didn't know what they doing, through the HAZ which'll still be their fault but down to pot luck as much as anything or it might be a fresh crack that wasn't visible to the naked eye because if you start doing some proper NDT the repair bill goes up and a new wheel often starts making more sense. If your business is refinishing wheels there's more of a finiancial incentive to take on repairs instead of sending the punter away to buy a new wheel...

If the fad for massive wheels with rubber bands for tyres, especially run flat rubber bands, died out wheels would be far less prone to cracking. If the fad continues it will probably get worse as manufacturers start taking weight reduction for economy/the environment more seriously. I hope i'm wrong but lighter wheels that are more reliant on heat treatments and/or grain structure from flowforming are gonna be less forgiving when repaired i.e. instead of a crack growing slowly resulting in a slow puncture things are gonna happen more quickly when fatigue takes over. Let's not forget that aluminium has no endurance/fatigue limit unlike steels or titanium etc

Not seen much on the subject of repaired wheels, but thousands of these are carried out in the UK every week, and it seems a shame that what comment on the subject there is doesnt seem particularly well informed, as this means establishing the best possible method of repair is very difficult, as the consensus view suggests repair isnt a feasible or safe option.

This presents what looks like a relatively accurate overview of wheel repairs: http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=1362&context=etd

However motor manufacturers make good returns on selling replacement wheels, so obviously furthering the idea of repairs not being appropriate or safe, is promoted quite vigorously for obvious commercial reasons.

 

[Rrunnach]

There have been times when I have decided not to attempt a repair. I have seen simple and, I have seen some nasty kerbing,which will result me telling owner to scrap wheel. It really is a judgement call and, what the welder is comfortable to take on.

A guy I sometimes do work for on classic vehicles, one day he popped in to ask if I would blank off holes where tyre pressure sensors would have been located (wheels came off a BMW) holes were approx 50mm dia. Needless to say, I knocked him back, I judge repair to be too risky for whoever would have driven vehicles repaired alloys landed up on.

Article within link now dated, I wonder if new reports can now be had?

 

[Chris Stevens]

There have been times when I have decided not to attempt a repair. I have seen simple and, I have seen some nasty kerbing,which will result me telling owner to scrap wheel. It really is a judgement call and, what the welder is comfortable to take on.

A guy I sometimes do work for on classic vehicles, one day he popped in to ask if I would blank off holes where tyre pressure sensors would have been located (wheels came off a BMW) holes were approx 50mm dia. Needless to say, I knocked him back, I judge repair to be too risky for whoever would have driven vehicles repaired alloys landed up on.

Article within link now dated, I wonder if new reports can now be had?

Not sure if the metallurgy of alloy wheels has changed a great deal since 1995? Mostly OE wheels are still either Al Si 7 or Al Si 10, which is marked on the wheel, with the aftermarket ones mostly unknown, but generally of much lower quality.

The reason there isnt more up to date accurate technical information regarding wheel repair, is purely and simply due to motor manufacturers making a good deal of money out of selling new wheels, and properly conducted testing which suggests wheel repair is perfectly safe, is obviously not likely to please motor manufacturers.

 

[hotrodder]

7 series materi


Not seen much on the subject of repaired wheels, but thousands of these are carried out in the UK every week, and it seems a shame that what comment on the subject there is doesnt seem particularly well informed, as this means establishing the best possible method of repair is very difficult, as the consensus view suggests repair isnt a feasible or safe option.

This presents what looks like a relatively accurate overview of wheel repairs: http://preserve.lehigh.edu/cgi/viewcontent.cgi?article=1362&context=etd

However motor manufacturers make good returns on selling replacement wheels, so obviously furthering the idea of repairs not being appropriate or safe, is promoted quite vigorously for obvious commercial reasons.

7 series materi I'm guessing a change of mind/typo but AFAIK outside of aerospace forgings the wrought 7xxx (and 2xxx) flavours are rarely used for wheels and obviously never for cast wheels. Washi Beam (BBS parent company or partner or something) are the only examples i'm aware of

I never said repairing wheels is unsafe, infact several times i've said if/when the repair fails usually all that happens is it cracks again and the tyre goes flat if the crack isn't discovered before it grows into the bead seat. I don't think it's a particularly good idea advise people how to go about it on a forum. Not because of liability or any other nanny state touchy feely stuff but because it's far from uncommon to have people join a forum asking about what TIG to buy one day, ask how to use it multiple times over the next couple of weeks and then jump to giving bad advice to other newbies and asking about repairing things like car wheels, bits of aircraft, pressure vessels and other things they shouldn't be touching yet even if it's personal use. Sometimes it's a paying job they want free advice on
I do think it's a good idea to point out how more involved it is than just "what filler rod do i need" hence me rambling on about liquation cracks, grain structure, flavours of Al alloys used and the effect heat treatment has on those alloys.

That masters thesis hasn't really changed my mind... their findings are at odds with what i stated about heat treatment and post weld strength/ductility/fatigue but also go against what pretty much every other authority on aluminium welding and metallurgy has to say on the subject. One common example would be passing tensile pulls when testing out welders... http://www.esabna.com/us/en/educati...he-tensile-test-requirements-with-6061-t6.cfm
Maybe porosity and inclusions in real life cast Al parts result in different behaviour to smaller lab test specimens? Wouldn't be the first time but worth pointing out that the repairs which they tested to destruction had first been DPI'd and/or X-rayed so were known to be free of gross welding flaws...

Quite what they were thinking by testing AZ92A on an aluminium wheel is beyond me as anyone that knows anything about metallurgy should have known it just wouldn't work

As Runnach said it's 20 years old and while it's better than nothing (seriously, nice find!) and the metallurgy of many wheels may not have changed much they had a small sample of alloys to play with... wheels are made from a wider range of flavours, these days at least. Production methods are bound to have improved and flow formed castings, if they didn't exist back then, are becoming more popular these days. At least on higher performance/OEM designs.

AlSi7 or AlSi10 markings cast into the wheel are only partial designations, BBS are one of the few big names who don't publish a list of the alloys they use, simply stating that they've developed proprietary flavours. No doubt there are others who might be happy to state they use AlSi7Mg and AlSi10Cu for their own brand wheels but don't mention that they also produce wheels to car manufacturers designs which may or may not use slightly different/modified flavours of Al. Modified alloys are mentioned here http://www.european-aluminium.eu/wp...-Applications-Chassis-Suspension-3-Wheels.pdf
I've posted this before and it's not about investigating the properties of repairs, just the regulations that apply to wheel repair in Canada http://www.bclaws.ca/civix/document/id/complete/statreg/5_97

I agree about the car manufacturers/stealerships. Wouldn't be surprised if the average stealer is quite happy to get a wheel repaired for a P/X on their forecourt but will tell the punter all sorts of made up on the spot BS about the dangers or wheel repairs if asked. Again, wheel painters have a financial interest in repairing wheels, if they can't/won't repair they will usually lose the customer to someone that does and i'll eat what's left of my hair if refinishing wheels isn't where the profit is made. That thesis was done in co-operation with a wheel repairer and amongst it's conclusions stated

Given the unknown state of damage caused by the road exposure it is inappropriate to offer a repair warranty or to accept liability for the repair

FWIW a large number of the wheel repairs i turn down are from people that have already have the wheel repaired by a painter and it cracked again after a few months...
The reason i don't touch wheels as a general rule is because i don't like comebacks/bad publicity, there are too many unknowns involved that are beyond my control and even trying to mitigate them a bit makes repair uneconomic unless it's a really rare/expensive wheel and the punter is happy to/wants to have the entire thing crack tested before and after repair. Last time i broke this general rule was for a cast magnesium Mahle 'gas burner' which are rarer than hens teeth and i only did it as due to the amount of TLC these wheels need to keep them clean they spend most of their life tucked away and when the car comes out for a track day or something other than pottling to a car show it's wearing more modern spun wheels which are virtually as light and not 60 years old...

 

[Chris Stevens]

The big problem with repair work seems to me to be the amount of myths and legends which surround it, which makes it very difficult indeed for anyone carrying out these repairs to select the most suitable filler materials, joint preparation, and weld process, without actually doing the repairs first and seeing what works best.

Damaged wheels are costing UK motorists an estimated £730 million a year, with a large part of that money going to those selling replacement wheels. When money like that is involved the reasons for repair work being seen in such a poor light, seems to me pretty clear.

 

[Richard.]

The big problem with repair work seems to me to be the amount of myths and legends which surround it, which makes it very difficult indeed for anyone carrying out these repairs to select the most suitable filler materials, joint preparation, and weld process, without actually doing the repairs first and seeing what works best.

Damaged wheels are costing UK motorists an estimated £730 million a year, with a large part of that money going to those selling replacement wheels. When money like that is involved the reasons for repair work being seen in such a poor light, seems to me pretty clear.

Chris HR has given a very in depth but very clear explaination as to why alloy wheel repairs are seen to be a hit and miss thing to do. The explanation was given from a metallurgist point of view not myth not in the way of making wheel manufactures more money just facts about what goes on when localised heat is applied to the different types of wheels. No one says it cannot be done and we all agree that in the event of a failure the chances are the tyre will deflate. (But it could be worse) depending on speed and road conditions driving style and whether it's been repaired before etc. the repair won't be as good as a new wheel due to the HAZ produced by welding. Can we agree on that? In most things that's ok but on an object that keeps you 6 inches off the road at 70mph and more is it still ok. Well that's down to you. I don't know enough about alloy wheel materials or processes so I'm not gonna loose sleep if someone has to buy another because I've refused the job. It's not hard to weld on them they generally take pretty well but I cannot predict what's going on under that weld. I don't have UT equipment at home so your guess is as good as mine as to whether it's any good below the surface. I know from previous posts there ain't much HR cannot and won't weld to astonishing standards and his knowledge of material science is waaaaaaay better than I'll ever know and if he won't weld them to avoid come backs then why would I do it knowing so much less about them. We can all put a stunning looking run along a wheel rim but the issue is deeper than that. (Literally).

 

[PhillipM]

You can weld them as prettily as you like, the bare fact of the matter is the NDT to check that the repair is actually safe cost more than buying a new wheel. Which is why the firms that repair them offer no warranty on the repair (and hope it covers their arses) - because they're only filling it in order to make some money on painting them, and hope they get away with the repair because of the safety factor the manufacturer built in (but, it's cracked once....)

If it were safe and structurally sound to repair cracked alloys you wouldn't see racers binning them every time they do one, as there'd be an industry pop up repairing them given how many must get damaged every weekend in the UK.

 

[Chris Stevens]

Like it or not the cost of replacement wheels, and the fact that most damage can be repaired pretty easily, means wheel repair is always going to be something that goes on, notwithstanding any amount of myths and legends which suggest repair is not a safe or technically viable option.

My point is that maybe it would be better to look at the best possible way to go about making the said repairs, rather than simply repeating ad infinitum the reasons why paying £400-500 for a new wheel is to be preferred over a £50 repair?

 

[Richard.]

Like it or not the cost of replacement wheels, and the fact that most damage can be repaired pretty easily, means wheel repair is always going to be something that goes on, notwithstanding any amount of myths and legends which suggest repair is not a safe or technically viable option.

My point is that maybe it would be better to look at the best possible way to go about making the said repairs, rather than simply repeating ad infinitum the reasons why paying £400-500 for a new wheel is to be preferred over a £50 repair?

You get what you pay for. You could get it done cheaper than that. I'm sure a mate with an ACDC Tig at 20quid for an hours work would do it no problem. After some shaping and finishing it would look as good as new. So that route would be even more appealing.
Each to there own. There is enough evidence to show adding a heat affected zone on an alloy wheel effects its integrity. It will never be "as good" it might be fine, there are probably methods these pros adopt to keep success rates high and heat input low along with most suited filler materials. Silicon based I would imagine. But the fact remains it will never be as good as a new one and I'm not ok with that on a wheel. So I don't adopt repairs.

 

[PhillipM]

Like it or not the cost of replacement wheels, and the fact that most damage can be repaired pretty easily, means wheel repair is always going to be something that goes on, notwithstanding any amount of myths and legends which suggest repair is not a safe or technically viable option.

My point is that maybe it would be better to look at the best possible way to go about making the said repairs, rather than simply repeating ad infinitum the reasons why paying £400-500 for a new wheel is to be preferred over a £50 repair?

So it's okay to bodge a safety critical item so long as it saves you enough money, is that what you're saying?

If so, I could push you some filler in the crack and paint it even cheaper than welding, I'm sure it'll stick the sides of it together somewhat.
No warranty though, of course.

 

[Rrunnach]

Chris never mentioned anything about "bodge job".

Regarding NDT, quick spray with dye-pen, will should up surface/sub-subsurface fault and, as many will know, is a very cheap method of NDT, if you know what to look for.