Cadillac CT6 Elevates the Science of Mass Efficiency

[jpd80]

Cadillac CT6 Elevates the Science of Mass Efficiency
General Motors
2015-03-13



DETROIT – Cadillac will use an advanced mixed-material approach for the lightweight body structure of the upcoming CT6 range-topping sedan. The structure is aluminum intensive, but the new Cadillac also includes 13 different materials customized for each area of the car to simultaneously advance driving dynamics, fuel economy and cabin quietness.

The CT6 will debut March 31 at the New York International Auto Show and go into production late this year at General Motors’ Detroit-Hamtramck assembly plant.

“This is the rocket science of automobile construction and manufacturing today,” said Cadillac President Johan de Nysschen. “With the CT6, we used high-strength aluminum and high-strength steels; lightweight chassis components; we integrate aluminum and steel where it makes sense; we eliminate every gram of mass possible, while achieving world-class performance.”

Weight reduction helps improve fuel efficiency, contributes to desirable vehicle dynamics and aids in creating a more resilient passenger cell. Sixty-four percent of the CT6 body structure is aluminum, including all exterior body panels – and the mixed material approach saved 90 kg (198 pounds) compared to a predominately steel construction.

“This new construction approach has enabled us to produce a world-class vehicle that is larger in size and includes more standard equipment while achieving lower overall mass,” Hester said.

• High-strength steel is used strategically to reinforce the body structure, and is also used in conjunction with high-strength aluminum to create a safety cage surrounding the occupants.
• The structural portion of the B-pillar is constructed completely of high-strength steel, which was chosen to aid vehicle ingress, egress and visibility, in addition to mass savings and added cabin quietness.
• A high-strength aluminum impact bar was added to the rear of the vehicle, and a combination of high-strength aluminum and steel was used for front and side impact zones to further increase passenger safety in the event of collisions.

A combination of aluminum spot welds, steel spot welds, flow drill screws, self-piercing rivets, laser welding, aluminum arc welding and hundreds of feet of structural adhesive are all used in assembling the body of the CT6.

Edited March 14, 2015 by jpd80

[jpd80]

While I can see the merit in innovation with all the jointing techniques used in this car, I can't help thinking that the challenges

in doing mixed construction was an unnecessary yoke GM placed upon engineering. It's as though GM started out originally

with a HT steel body and simply replaced as much as it could with aluminum and a lot of the technicial detail is wrapped up

in specialized jointing required to retain the HT steel parts.

 

How much technical difficulty would GM have avoided by making this car 100% aluminum,

and will they have a problem down the track with contamination of panels......never invite the devil.

Edited March 14, 2015 by jpd80

[sullynd]

I wonder how many GMI Beer Can commenters will proclaim an aluminum extensive CT6 as the best thing ever.

[Ron W.]

Ya can't build a vehicle out of aluminum, it's not tough enough.

[jpd80]

BMW prices don't work for Cadillac buyers.

Edited March 15, 2015 by jpd80

[Dave-S]

And how is Cadillac's construction method any different than what Ford is doing (or considering doing)?

 

https://media.ford.com/content/fordmedia/fna/us/en/news/2014/06/03/ford-builds-on-advanced-materials-use-with-lightweight-concept.html

[Anthony]

And how is Cadillac's construction method any different than what Ford is doing (or considering doing)?

 

https://media.ford.com/content/fordmedia/fna/us/en/news/2014/06/03/ford-builds-on-advanced-materials-use-with-lightweight-concept.html

One is a concept?

[fuzzymoomoo]

And how is Cadillac's construction method any different than what Ford is doing (or considering doing)?

 

https://media.ford.com/content/fordmedia/fna/us/en/news/2014/06/03/ford-builds-on-advanced-materials-use-with-lightweight-concept.html

One is a concept?

 

I believe this is what pioneer was talking about when he said that the next Focus will "use aluminum extensively"

[92merc]

So, did they use their new miracle welding method on the aluminum? Or go rivets and adhesive?

[RichardJensen]

Seems like a bit of both, as the press release refers to use of hundreds of feet of structural adhesive as well as self-piercing rivets.

 

I tend to agree w/JPD. This seems to be a bit more complicated than going with 100% aluminum, and reminds me a bit of how Toyota was so proud of their three-part Tundra frame alleged to be superior to the F150, etc. To say the least, it does not seem elegant, and it does not seem to be a process that can be easily sold to potential customers.

[jpd80]

Yes, it's like the car was developed as separate modules and brought together with new jointing technologies

I wonder if GM got so caught up with enthusiastically solving technical issues that it "lost the rabbit" by insisting

that the car retain a steel floor pan and firewall, something that could be easily and effectively done in aluminum....

 

Ford can build and sell alloy body F150s form $25K to $60K, sure it has a separate steel frame

but look at the processes there versus what GM is asking us to believe is revolutionary with Omega

and I guarantee that the logic falls apart very quickly.

 

One final thought, a previous Mustang was developed with a DEW platform floor module (steel)

imagine if that had been aluminum and For insisted that engineers develop a steel car to use it.

That's the basic gambit of Omega in reverse.

Edited March 16, 2015 by jpd80

[Fgts]

Yes, it's like the car was developed as separate modules and brought together with new jointing technologies

I wonder if GM got so caught up with enthusiastically solving technical issues that it "lost the rabbit" by insisting

that the car retain a steel floor pan and firewall, something that could be easily and effectively done in aluminum....

 

Ford can build and sell alloy body F150s form $25K to $60K, sure it has a separate steel frame

but look at the processes there versus what GM is asking us to believe is revolutionary with Omega

and I guarantee that the logic falls apart very quickly.

 

One final thought, a previous Mustang was developed with a DEW platform floor module (steel)

imagine if that had been aluminum and For insisted that engineers develop a steel car to use it.

That's the basic gambit of Omega in reverse.

Can't really compare the F150 to the Caddy, for instance the F150 have a much higher ROI,mission and volume compared to Omega.

 

Other examples is the Omega is unibody compared to BOF F150 (which still uses a steel frame ofcourse) plus Omega is a highly modified Zeta as the F150 is all new.

[Anthony]

Not to play devil's advocate, but Ford's own lightweight concept has many mixed components including high strength steel in the passenger cell.

 

[RichardJensen]

Right. But there you're building to clear price point constraints. That vehicle's a Fusion, and the first vehicle we're expected to see this on is a Focus.

 

With a Cadillac, you would think that there aren't the same price constraints unless, as previously hinted, the Omega platform is slated to underpin entry-level Buicks and Chevrolets, in which case, why even bother with anything at all? Go directly to Chapter 11. Do not pass Go, Do not collect $200.

[Anthony]

Yeah, but it's also a concept too. I mean they wanted a lightweight concept, they could've just built the entire thing out of carbon fiber and called it a day. But they wanted to show what was production and economically feasible The real question is, is a 100% aluminum vehicle inherently better then one that is mixed as Ford and Cadillac have shown? Would Ford be building a 100% aluminum unit-body luxury vehicle or one that is mixed....even if sharing platforms with lowly Fords?

 

I sure don't know.

[RichardJensen]

The real question is, is a 100% aluminum vehicle inherently better then one that is mixed as Ford and Cadillac have shown?

 

If your definition of better encompasses "as strong, but lighter", then yes, a 100% aluminum vehicle is better than the mixed construction.

Edited March 16, 2015 by RichardJensen

[Anthony]

Well, I think it's safe to say if they are showing it on a Fusion....it would be the same for the MKZ? (oops, you edited out the premium vs entry level vehicle comparison which makes this not make sense now)

 

As much as it pains me to say so, I think we are looking a bit too critically at what Cadillac has done.

Edited March 16, 2015 by Intrepidatious

[RichardJensen]

Well, I think it's safe to say if they are showing it on a Fusion....it would be the same for the MKZ?

 

As much as it pains me to say so, I think we are looking a bit too critically at what Cadillac has done.

 

Right.

 

But the MKZ is not playing in the same space as the Omega vehicles. The Omega Cadillacs are expected to have an MSRP over $90k for certain trims. Probably over $100k.

 

For that price, you're trying to sell someone that your mixed aluminum/steel product is better than the Audi's all aluminum construction? It's a tough sell---you're a newcomer to the field and you're trying to sell your method as better than that of an established player? That's like Toyota insisting that their Tundra frame was better than the F150's: Where's your credibility in the market to say that?

 

And conversely, if you're going to try to sell a >$100k Cadillac with the same basic platform as a ~$40k Chevrolet (which is the only reason I can see for using this mixed material construction), then, see previous remarks re: Chapter 11.

Edited March 16, 2015 by RichardJensen

[jpd80]

Can't really compare the F150 to the Caddy, for instance the F150 have a much higher ROI,mission and volume compared to Omega.

You do the math, Omega probably cost around $1 billion and will most likely be built in two plants with a max of around 4,000 to 6,000/mth. and I'm being very generous here..

Now compare that against F150 which cost around $2 billion and will be built in two plants at a rate of around 40,000/mth.

 

By those thumbnail figures, the ROI for F150 will be much quicker than Omega.

 

Other examples is the Omega is unibody compared to BOF F150 (which still uses a steel frame ofcourse) plus Omega is a highly modified Zeta as the F150 is all new.

If you look at Omega, nothing of Zeta actually survived save for a small piece of steel floor pan,. in zeta, that had two giant longitudinal log supports which are no longer present in Omega which uses GM's new Layer build technique. The other main feature of Zeta was suspension and parts list, I can tell you that basically none of that survived. and while Zeta may have served as the inspiration of Omega, nothing really survived the redevelopment.

 

I just don't see the sense in saving that steel floor pan and firewall when so much else is already aluminum.

Edited March 16, 2015 by jpd80

[twintornados]

Bu...bu....bu....but aluminum is baaaaaaaad.....

[jpd80]

Strange how the compartment area is still steel while the rest of the car has been changed to Aluminum construction,

it's like the half and half of cars but very complex to do because of duplicated processes and the multiple joining

processes required. What's really going on here, what am I missing?

 

Here's a thought, applying Omega's mixed construction to existing production lines may allow GM the luxury of

retaining almost all of the existing stamping and body shop operations and thanks to the modular assembly of

the alloy attachments, only changing some of the assembly stations to accommodate the changes in material and

jointing processes.

 

Aluminum sub assemblies would require their own small stamping and assembly points but that may be done as a

simple add on step and the sub assemblies delivered to the required assembly stations.

 

The money saved by avoiding the gutting of two plants may make the process much more viable

than full tear up and 100% Aluminum.- which is probably the point Fgts was trying to make above.

 

Trying to understand the methodology here...

Edited March 17, 2015 by jpd80

[Fgts]

Strange how the compartment area is still steel while the rest of the car has been changed to Aluminum construction,

it's like the half and half of cars but very complex to do because of duplicated processes and the multiple joining

processes required. What's really going on here, what am I missing?

 

Here's a thought, applying Omega's mixed construction to existing production lines may allow GM the luxury of

retaining almost all of the existing stamping and body shop operations and thanks to the modular assembly of

the alloy attachments, only changing some of the assembly stations to accommodate the changes in material and

jointing processes.

 

Aluminum sub assemblies would require their own small stamping and assembly points but that may be done as a

simple add on step and the sub assemblies delivered to the required assembly stations.

 

The money saved by avoiding the gutting of two plants may make the process much more viable

than full tear up and 100% Aluminum.- which is probably the point Fgts was trying to make above.

 

Trying to understand the methodology here...

Thanks for shining light on GM may not have to gut-out a factory to make the CT6 because of it's construction.

 

I'll add another reason is as said the floor pan and I believe the inter passenger compartment is carried-over from VE-Zeta. A Chevy and Buick version can be all steel while the Caddy is the hybrid build, that will give the Cadillac an edge in weight and handling over it's corporate cousins while platform-wise its technicality the same.

[jpd80]

Thanks for shining light on GM may not have to gut-out a factory to make the CT6 because of it's construction.

 

I'll add another reason is as said the floor pan and I believe the inter passenger compartment is carried-over from VE-Zeta. A Chevy and Buick version can be all steel while the Caddy is the hybrid build, that will give the Cadillac an edge in weight and handling over it's corporate cousins while platform-wise its technicality the same.

And that's the big question for GM, what do they want to do with this platform, reserve it for high series Cadillacs

with premium prices or offer other versions for added scales of economy. Given the anticipated price spread,

something has to give..

Edited March 17, 2015 by jpd80

[RichardJensen]

Thanks for shining light on GM may not have to gut-out a factory to make the CT6 because of it's construction.

 

I'll add another reason is as said the floor pan and I believe the inter passenger compartment is carried-over from VE-Zeta. A Chevy and Buick version can be all steel while the Caddy is the hybrid build, that will give the Cadillac an edge in weight and handling over it's corporate cousins while platform-wise its technicality the same.

 

Possibly.

 

But that still leaves you in the odd position of sharing a passenger cell between a super premium $100k luxury sedan and a cop car.

[sullynd]

What's the delta between a Police spec RWD Tahoe and a fully blinged out Escalade?

 

Not that those equate to cars, but I'm curious if the spread is close.