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Anthony

As Ford spends big, GM joins aluminum with simple welds

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I would think since for has been dealing with aluminum for a while with PAG and of course F150 testing since 09, that if there was a better way to bond panels they would have done it. I suspect Ford feels their way is the better way. I have no expertise in this area, but I think Ford has done it's homework.

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I can't speak to the metallurgy.

 

But I can tell you that you have to retool eventually anyway, so I'm not sure how GM is saving a fortune.

 

Ford's methods are proven, and I can't quite see how trying a relatively untested method to build an entire truck body, when trucks are the major driver of your products, is a good idea.

 

--

 

Furthermore, the challenge of welding aluminum is well understood. I have difficulty believing that a solution as simple as cutting circles into a welding cap is sufficient to fully address the situation.

Edited by RichardJensen

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Each cap lasts for about 4,000 welds. They are resurfaced after every 50 welds until they wear out. GM spends less than $1 for each cap.

 

 

This doesn't seem to be a very durable solution. I don't know if Pioneer can speak to how often the welding guns on steel assembly lines have to be taken down for maintenance, but this seems to suggest that the caps have to be resurfaced more than once an hour when the line is running full speed, and the caps have to be replaced at least once a week.

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Ford welded the hoods on the 2004 to 2008 trucks. We went to rivets for a reason. Better bonding. And you have to retool anyway. The weld controllers are different.

 

Whoever wrote that they won't have to retool doesn't know how body shops work. By the time the next model comes along, you retool because the robots and other equipment are usually worn out.

Edited by Pioneer

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Ford welded the hoods on the 2004 to 2008 trucks. We went to rivets for a reason. Better bonding. And you have to retool anyway. The weld controllers are different.

 

Whoever wrote that they won't have to retool doesn't know how body shops work. By the time the next model comes along, you retool because the robots and other equipment are usually worn out.

Pioneer, as you have stated, welding aluminum is nothing new. What we are led to believe is GM has all sorts of patents on this "revolutionary " new process. I would have to believe Ford left no stone unturned on the options of fastening aluminum once the decision was made that the weight savings was the objective.

 

You have any insights of Ford experiments/testing with other weld methods? I wonder what the big military contractors (Navistar, Oshkosh etc) have done with their aluminum components.

 

Also I would have to imagine Big Al had some experience on the subject at his old "shop".

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You have any insights of Ford experiments/testing with other weld methods? I wonder what the big military contractors (Navistar, Oshkosh etc) have done with their aluminum components.

 

or Morgan Olson for that matter....

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We "serviced" our weld guns between each shift. We could get about 11 hours production out of a set of caps, and the weld slag had to be chipped off. It just depends on how many welds you do. Every certain number of welds, depending on the heat and number, you dress the top automatically with a cutting blade the robot drives the gun to, or in the case of a pedistal gun, the dresser is on the robot end of arm tooling.

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About why Ford didn't weld, I can only repeat what I've heard.

 

When the parts were steel, they would have a coating of oil on them to help the stamping process. You can't use that oil with aluminum because then the adhesives wouldn't stick. You would have to dip clean the stamped parts before assembly.

 

We use another substance to lubricate the part. In order to weld, that substance would need to be dip cleaned off the part before assembly. Either way you would be looking at a major process change and cost.

 

Riviting is stronger and has better NVH properties as well. And, just to clarify, there are a few welds in the new truck. The bed floor supports are welded so when you haul things in the bed, the rivit heads don't get damaged.

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And I don't understand. GM wasn't previously cooling their weld tips? That's bad news. You can get weld failure from that.

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And I don't understand. GM wasn't previously cooling their weld tips? That's bad news. You can get weld failure from that.

 

I begin to understand why my 15 year old Mercury is so quiet and solid compared to a similar vintage GM product.

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We "serviced" our weld guns between each shift. We could get about 11 hours production out of a set of caps, and the weld slag had to be chipped off. It just depends on how many welds you do. Every certain number of welds, depending on the heat and number, you dress the top automatically with a cutting blade the robot drives the gun to, or in the case of a pedistal gun, the dresser is on the robot end of arm tooling.

 

BTW: Thanks for all the info.

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And I don't understand. GM wasn't previously cooling their weld tips? That's bad news. You can get weld failure from that.

Bu..bu..bu..but look at how much money they saved!!!!

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Bu..bu..bu..but look at how much money they saved!!!!

Which I'm sure they are blowing on building new Cadillacs...

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I know with my exposure to US Military equipment, the Humvee has lots riveting on it, the Bradley,MLRS and M113 (all aluminum, but much thicker) are welded together.

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All things being equal the spot welding is stronger as it does not introduce a place for a fatigue stress crack to propagate from. The adhesive bonding the joint will help mitigate this but not stop it.

 

Spot welding aluminum is not new technology by any stretch and has been used in the aircraft industry for several years now, for that exact reason to get rid of rivets and eliminate the rivet hole and the potential of stress crack propagation, the process GM has developed overcomes some of the short comings traditionally encountered with spot welding aluminium and is suitable for the type of alloys and thicknesses used in the automotive industry.

 

Is riveting and bonding better than spot welding, that is entirely dependant on application. For the intended application of automotive body assembly there is no advantage durability wise, it is a wash. Spot welding may have a better long term benefits in terms of minimizing the number of locations for fatigue cracks to propagate from, but the big advantage is cost and time.

 

Spot welding aluminum requires over twice the current to comparable thickness sheet steel but has the advantage of needing half the time to complete the weld.

 

NVH is more easily be transmitted from one panel to the next in spot welding due to the more homogenous structure compared to rivets and adhesive, the NVH absorbed in the rivet/adhesive joint is also one of the primary causes of stress crack propagation around the rivet holes in this type of assembly, since vehicles are not designed for 20 year life spans but something closer to a decade these issues will not be readily apparent for many years, once the aluminium structures begin to work harden through years of repeated flexing, this could become a point of contention.

 

Spot welding AL is not new technology, this is an adaptation of current tech that solved the existing cost and time issues that prior prevented it from being used in this type of application.

 

If you want think of this way, what if it was a steel body, would you prefer rivets and adhesive or spot welds ?

 

Eventually we will see rivets and adhesive for aluminium joints go the same way rivets went for steel assemblies in mass production items.

 

Ford used at the time what the best tech available counting for cost, time and durability.

GMC took existing tech and solved the issues that prevented it from being cost effective method for assembling aluminium auto bodies.

Just two different approaches is all.

 

But I have to give GM a kudos on this one as a smart move, as I imagine it will be licenced to other manufactures in time for their use, and not just limited to the auto industry.

 

 

Matthew

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GMC took existing tech and solved the issues that prevented it from being cost effective method for assembling aluminium auto bodies.

 

With all due respect, I'm going to give a company that has spent 20+ years researching aluminum the benefit of the doubt here.

 

If they saw benefit in spot welding aluminum in only one area (the cross-members of the truck bed), I'm going to go out on a limb and trust their engineers, their metallurgists, and their manufacturing engineers, over those employed by a company that to this date has not produced steel bodied vehicles that hold up as well as Ford's.

 

I mean, think about it: When was the last time you got into a ten year old GM and thought, "Wow, this vehicle has held up *much better* than a ten year old Ford"? And we're supposed to believe that this company has somehow figured out how to fabricate more durable bodies than Ford in aluminum?

 

Come on. They have to demonstrate excellence in a much easier to work with material first.

Edited by RichardJensen

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I don't know if aluminum welding would be that advantageous over rivet and glue, the only advantage I see is that GM

could change over to aluminum with less disruption by keeping existing work stations and constructional process.

 

Surface coatings on aluminum have now enabled superior glue bonding, much was made of this before release of F150

with Ford wanting Alcoa to extend its coating process to to lower tier suppliers. So while rivetsand glue are a major part of

the change to assembly process, I have a hunch that the processes and work flows nowin play with aluminum, enables Ford

to actually speed up the process through stamping and body shops.

 

Recently, Pioneer has mentioned new advantages in spreading work fronts by making sub assemblies in the pressing

area before the major assembly takes place in the body shop - I think that is key to increasing scales of efficiency

in Ford's process and probably why GM has issues with switching to aluminum construction at the moment...

GM is trying to change by doing the minimum, maybe thta helps in the short term but perhaps it does not

solve other choke points that already exist, something Ford looked at and added as part of the change.

 

Sometimes total commitment requires letting go of everything established in a safe manufacturing process and doing

what seems, unnecessary, impossible and maybe insane to established industry wisdom and culture.

Edited by jpd80

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Spot welding aluminum requires over twice the current to comparable thickness sheet steel but has the advantage of needing half the time to complete the weld.

Matthew

The aluminum used in the F150 is much thicker than the sheet steel used in prior versions of the truck.

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Ford would not have gone to the trouble effort and expense of completely gutting and rebuilding 2 plants without a significant advantage.

 

Either Ford's process has other big advantages or their technology has future capabilities beyond welding that GM won't be able to match with simple welding.

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This is only the start for Ford but GM has yet to start...

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I had the opportunity fairly recently to be involved intimately with these exact issues for some assemblies using the same alloys and gauge materials for support structure assemblies in equipment. We looked at both spot welding and steel rivet with adhesive for doing these assemblies ( this is a project in the hundreds of millions)

 

The general consensus between us and the consulting metallurgical engineering firm (who also happens to consult for aerospace, aeronautical, the auto industry and military) that it was a wash with spot welds only showing an advantage over extended periods of time due to the propagation of stress cracks from the holes made by the rivets.

The cost associated with spot welding using the existing tech for high capacity manufacturing made it cost prohibitive, not that riveting/adhesive is cheap either. So on that note rivets and adhesive it was.

 

For this application in auto bodies there is NO measurable mechanical strength or durability advantage between the two. The only reason Ford went the way they did was cost and time of assembly, so again cost. The time of spot weld with AL does not change drastically as it does with steel when material thickness increases.

 

GM aslo was not developing a complete AL body and did not have the dead lines or constraints that come with that, but started working with smaller AL sub assemblies. They could have just as easily riveted and bonded them also. They had the time to spend, and since it was not a huge commitment of their resources unlike the full aluminum body of the F series they had the resources to investigate whether spot welding tech could be improved to become a viable option cost wise for high speed manufacturing.

 

And if any of you think that GM developed this in house you're smoking crack, it was farmed out to a third party to solve, funded by GM so in turn GM owns the tech.

 

Spot welding of AL has been around since the 1950's but was only used in cases where riveting or bolting was not suitable or thicknesses prevented friction stir welding, this is basic tech that is long proven (longer than adhesive) and understood, it was just modified to resolve the issues of time and cost for high production manufacturing.

 

Holy smokes guys quit blind drinking the cool aid.

 

You watch the next all AL body Ford cranks out will take full advantage of this or similar modifications for high production AL spot welding.

At the end of the day it produces an equivalent product at a fraction of the cost.

 

So by what everyone is saying here, you would rather Ford stick with a slower more costly assembly method that offers no practical advantage in durability ?

 

Ya I didn't so.

 

Matthew

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This is only the start for Ford but GM has yet to start...

GM has started the center floor pan structure (rocker to rocker) of the vette is an aluminium sub assy that is spot welded together.

 

Matthew

Edited by matthewq4b

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Holy smokes guys quit blind drinking the cool aid.

 

Do you realize that you are uncritically accepting GM's own account of the value of their innovations, and that those claims cannot be independently verified?

 

If we are advocating that Ford's approach is more sound, it's on the basis of Ford running a better business and having overall better engineering than GM for the last thirty years or so.

 

If GM had demonstrated an ability to build steel vehicles better than Ford, I might be willing to take their assertions that they can build aluminum more efficiently than Ford at face value, but they can't and I won't.

Edited by RichardJensen

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