Car and Driver once had a piece about a largely aluminum Audi that they were reviewing [1]. They got into an accident (not terrible--no one hurt), and the $30,000 repair took months at the only facility in Michigan that could repair aluminum-built cars. Now the Audi used aluminum in its frame, and maybe that's all the difference in the world, but I'd like to see Ford address repairability.
Otherwise, I'd welcome not only the weight reduction, but the avoidance of rust and body rot.
I have an aluminum Audi A2, and it's great! The fuel economy is good, and it's perky because of the lightness. Also happens to be one of the most reliable vehicles in it's age group. It drives really well because of the low center of gravity and thoughtful suspension, even if it is narrow and tall on the outside. It's actually a car that has been coherently designed.
The model was too expensive to produce and was cancelled by Audi in 2005. No aluminum Audis after that except some sport models. It's sort of a hidden gem.
To an outsider, making a big pickup truck from aluminum is like creating a paperweight out of some expensive lightweight material. Isn't the whole point of a pickup to most people (not all) being imposing and bulky? They even mention the 5000 pound weight in advertising, I assume they try to impress that it weighs a lot.
> Isn't the whole point of a pickup to most people (not all) being imposing and bulky?
This is a whole discussion in itself. Modern pickups, to my eyes, look more like cartoons of pickups. The manufacturers (in my mind, especially Nissan and Ford) go out-of-their way to add big, chunky fenders and grills and such. It must sell. And small trucks are disappearing: Ford's Ranger is gone in the US market, and Toyota's Tacoma is now as big as the F150 of a decade or two ago.
The fuel efficiency of the A2 is mostly due to it being a small car with a small engine. However if they saved 100kg from the body mass, that's l0% of the A2's overall mass. Shame they cancelled it, people who had them loved them.
The windshield wiper motor died and I ordered a new one from a German web shop Audi Zentrum Göttingen for 100 euros (payment with Paypal), and a small town VAG specialist changed it. There are lots of repair shops around here that fix these cars just fine, even when they weren't imported here when they were new. So all cars are second hand imports. The wiper motor part cost would have been more than double locally. It helped to know some German. :)
Then the rear brakes also had to be fixed for the yearly checkup, normal wearing parts. And the internal heater had a connection problem, discovered when it started being cold enough that it was used (it's an aftermarket job anyway, to connect the car to an electricity outlet and warm up the engine block with a resistor and the interior with a resistor+fan).
I've had the car for six months and from rough memory, spent maybe 400 euros for maintenance.
I don't think body shops will much care either way once they get over the initial shock and how to prep for paint. Most body work these days is remove & replace of large panels. Instead of welding they will have to use adhesives (or train their workers to use a TIG) and they will need to have a dedicated set of abrasives for the aluminum work.
Aluminum damage to the structural (sub)frame is a whole different beast than in the (non-structural) body panels. Aluminum work hardens when bent. When it hardens it become brittle and can crack from stress and vibration. Any damage has to be completely replaced with fresh metal.
Corrosion is still an issue with aluminum though it tends to self-protect itself. If you really want to mess up something aluminum add some mercury..
More often than not, repair places simply replace body panels as it is, because trying to fix much more than minor dings tends to be more labor intensive than just putting a new one on. So for the average service shop, it wouldn't be much difference.
The Acura NSX had an aluminum body back when it was first introduced in 1990. I'm glad to see aluminum bodies now being used in more mainstream vehicles.
Wouldn't the lack of weight be a factor in snow, or generally poor-traction situations? Being in Buffalo, NY I already see plenty of trucks fishtailing as it is.
Whatever happened to putting sandbags in the back of the truck? When I lived in Buffalo, that was the preferred method of adding extra weight in the winter. Bonus: free sand in case you got stuck somewhere :-D
On the flip side: how will the ever present salt affect the aluminum body?
Yea, sandbags are the preferred method. Problem is, there are quite a few people that still think having a truck makes you impervious to poor driving conditions...and they skip the sandbags.
All metals will corrode in the presence of salts. Though aluminum does not exhibit rusting like steel does, it will develop a chalky film and pitting in the metal surface when exposed to salt for long periods. I believe that this is aluminium oxide.
Sandbags are pretty standard in the northland[1]. Although, some trucks (looking at you Ford Ranger / Mazada B4000) are just bad on snow and ice (described as death traps).
If I still lived in a state that used salt, I would follow the precaution of getting a year round carwash pass and going once a week. Plus, a good underbody coating works well.
1) put them over the back wheel, NOT loose in the bed so they slide. Rope or bungee cords are your friend.
There's no lack of weight with the F150: curb rate appears to range from about 4700 to 6200 lbs [1]. The trouble with trucks in snow is the distribution of that weight.
Amen, it's the distribution of the weight. Also, if there is less weight, one can use an narrower tire to provide the same amount of pressure per square inch of contact patch.
In other words, less weight + smaller tire == same snow bite. Smaller tire? Cheaper tire. Smaller tire? Less rolling resistance. Lighter spare tire.
Lighter truck? Better gas mileage, better stopping, better cornering. If there is a 1000 lbs less to stop on the snow, that will make a huge difference.
Too many people think that their all-season tires can do everything. They can do everything, but they don't have the dry grip that summer tires do in warm weather, and they don't have the aggressive siping, channels and the tread compound for ice and very cold air temperatures of winter tires. All season tires do everything far worse than their specialty counterparts do, and it demonstrates itself the most every winter.
I drive lightweight RWD sports cars all year round, and we get plenty of snow in Boston. Never have had an issue with winter tires, and sometimes I deliberately seek out empty unplowed parking lots just to have extra fun in.
Around here (Utah), we see TONS of people driving on the steep mountain roads in the winter with expensive AWD/4x4 cars, trucks, and SUVs that they bought specifically for mountain driving yet are equipped with summer or all season tires. Unsurprisingly, a lot of these people end up in the ditch. Snow tires really are a night and day difference for winter driving conditions - I'd rather have a FWD (or even RWD) car with snow tires than AWD with summers or all seasons.
Snow tires are pretty cheap compared to body work too ;)
Many cars prior to the F-150 have had aluminum bodies (Land and Range Rovers, for instance) that sold well. I would think that many truck drivers are more concerned with towing capacity, power and fuel economy than the specific metal the body is made from. Besides, the aluminum won't rust!
If you're buying a F-150, you are more concerned with it holding up[1]. This is the vehicle of construction sites and farmers. It is truly the vehicle of I need to haul that stuff over there where they might not be a road. The concern is that the 2014 F-150 will not hold up and be more expensive to repair.
This is Ford's flagship vehicle. It cannot just sell well, it must put up amazing numbers. Its the iPhone of the car world.
1) the F-150's gas mileage isn't stellar, but it does even out when hauling.
My initial concern would be metal fatigue, if they're building the frame from aluminum. But that's a hardware problem and I'll assume they've thought about it first.
The rollout of the EcoMod twin-turbo six-cylinder in the F-150 gives me some faith that they're not the usual run-of-the-mill idiots.
The Land Rover has had an aluminium body since 1948, plenty of time to figure out if it's a good or bad choice for an off-road vehicle.
There seems to be a lot of FUD around the new F-150, and as a European, it's hard not to see the similarities with U.S reactions to small turbocharged engines, and smaller vehicles in general.
The series LR's had complete Birmabright (aluminum/magnesium alloy) bodies; though the more recent models Discovery I/II, LR3, Range Rover have used only aluminum body skins.* Meaning the structural body is steel, though the outward panels are aluminum.
The 2013 Range Rover has a complete aluminum body (skin and structure), with a 700lb weight reduction for US models.[1]
If you look at the wikipedia page for that ship, you'll see that is isn't even built from aluminium! Really, that link is a bunch of crap. When was the last time you heard of a plane's aluminium skin catching fire (apart from when there is a bunch of avgas or jet-a on fire?)
The headline addresses the very real concern that Ford has with the image their customers might have with an aluminum truck. They're concerned that people might equate aluminum with flimsy. Expect competitors to encourage this thinking (till their own aluminum designs are ready). Image is very important in the pickup truck market.
But to give potential critics some credit, aluminum can be made very thin, like a beer can, in which case it is flimsy. It can also be made thicker, like the aluminum siding of the 60s and 70s, in which case it may still ding easily and lose its appearance.
I am glad to see that trucks are catching up with bicycles!
The bicycle business moved to aluminium a generation ago. For at least a decade carbon fibre has been the material of choice for road bikes. Nowadays if you are from the school of 'steel is real' then you are going to have to buy a cheap 'bicycle shaped object', get something custom handmade or go for something deliberately hipster-retro.
Clearly there have been aluminium bodied cars for some time, even a 'truck' if you count the Land Rover. However, there is aluminium and there is aluminium. I suspect that the new Ford truck has a bit more to it than the Land Rover (or even the Audi A2) has.
In the bike business there is 6 series aluminium and 7 series aluminium, to name the most popular alloys. The original aluminium frames were welded together tubes, for a while 'bonding' was experimented with but that proved to be unreliable. The current state of the art is 'hydroformed' aluminium, welded. The 'hydroformed' frames are works of art, with the metal where you need it for strength, the grain structure also aligned for strength. The tubes are anything but plain cylinders and much more useful for design than was possible in the days of steel.
Does anyone have any more technical information on what the processes and alloys are going to be on this new-fangled truck?
> Nowadays if you are from the school of 'steel is real' then you are going to have to buy a cheap 'bicycle shaped object', get something custom handmade or go for something deliberately hipster-retro.
As it happens I ride steel, primarily for the first reason you mention! I am also from the UK and I was over-generalising about what is available. There are plenty of people that still prefer steel, this is something I like about bicycles, there is a lot more individuality going on with bikes than you get (generally) with motoring.
> Nowadays if you are from the school of 'steel is real' then you are going to have to buy a cheap 'bicycle shaped object', get something custom handmade or go for something deliberately hipster-retro.
You might consider this to be in the second category, but here is a high-end bicycle maker that does exclusively steel frames: http://www.rodcycle.com/
I have two areas of expertise on this matter. First, I was on UW-Madison's competition-winning FutureTruck team about 10 years ago. We were, IIRC, the only team of about 15 other universities that replaced our competition car's (a Ford Excursion) entire frame with aluminum. In addition to replacing many other steel parts/assemblies with aluminum equivalents, we managed to bring the newly parallel hybrid SUV under stock weight... despite adding a large battery pack and motor. The thing I learned from this experience was: even though aluminum has about 1/3 the density of steel, your parts end up being about 50–55% of the steel weight because you need to add more aluminum to maintain equivalent strength. Basically, given the same tensile strength properties of a part, an aluminum one will be about half as heavy.
Second, I worked as a payload mechanical engineer for a number of spaceflight systems. Suffice to say, our base material for consideration was aluminum. Sure, we deferred to steel for certain applications (e.g., ball bearings, rat cage bars, fasteners, etc) and to myriad materials in others, aluminum was the standard. It has a tremendous strength/weight ratio, can be alloyed in many different ways to get different characteristics, is non-magnetic, is relatively cheap, and can have a number of interesting surface coatings applied. About the only major systemic problem aluminum has is that it is difficult to weld. Not impossible, as my FutureTruck experience tells me, but difficult. It didn't matter to us, though, since NASA generally frowns upon welded joints anyway. Too much strength variation due to heat stress and potential for FOD if not ground properly.
Anyway, I've been waiting for the auto industry to catch up to a bunch of college students for 10 years now. Nice to see one of the Big Four finally getting it. And cheers to the smaller car companies that have been doing it for years.
Since you seem to have some expertise, maybe you can answer this question: Is there a work function difference between steel in contact with aluminum, and does it accelerate corrosion in the steel?
The three main things to be concerned about are corrosion, galvanic corrosion[1] and galling[2].
Corrosion is more commonly known as rust, but that's technically reserved for steel (or, more accurately, iron) oxidation. Aluminum certainly corrodes, but it corrodes into aluminum oxide, or alumina, which is actually a ceramic that is stronger than aluminum. In fact, good luck using aluminum without a coating of alumina... it naturally occurs on the surface of atmospherically exposed aluminum. As a result, when a chunk of aluminum is broken off of a larger piece, the material almost immediately forms a protective layer of alumina. It's almost like aluminum self-heals in the presence of oxygen.
Galvanic corrosion occurs when dissimilar metals come into contact amidst an electrolyte solution. In the case of vehicles, that's usually seawater/sea-mist or salted winter roads. While saltwater is also responsible for accelerating normal corrosion, it also plays a part in galvanic corrosion. So yes, having aluminum and steel touching is a recipe for galvanic corrosion, but galvanic corrosion is not black-and-white. Each metal has an anodic index; a high or low anodic index doesn't matter all that much. What matters is the difference between the anodic indices of the touching metals. For aluminum and steel, that difference is quite small, so galvanic corrosion isn't a huge issue, but it's not negligible either.
Galling occurs when the sliding friction of two parts, say a screw and its threaded mate, results in plastic deformation, usually in the more ductile of the two pieces. This generally doesn't come into play in the construction of a vehicle because many parts are attached either by welding or by a bolt-nut combo. Choosing the correct materials for the bolts and nuts (basically, just use hardened, but not stainless, steel) gets rid of this concern in most cases. In cases where one must screw a steel fastener into a threaded aluminum piece, a helical insert is usually prescribed. While many manufacturers make these, we typically used Helicoil for spaceflight ops because they're tested and rated for spaceflight (batch traceability, proper composition docs, etc).
On PBS where I saw a brief description of aluminum and how difficult it was to refine and even when abundant supplies were available it's a soft metal if not an alloyed with copper or other metals. And the alloy is still soft unless it's forged correctly it takes time and heat, or so the show indicated, it was quite interesting.
For all that work you'd think these days carbon fibre would be just as good, economically-wise.
All pickups use body-on-frame construction (image: http://bit.ly/1cFsxn2). The backbone that bears most of the load remains steel. It probably always will, because the strength requirements would necessitate a huge, expensive chunk of aluminum.
If the bed interior is aluminum, they will have to increase the thickness compared to steel, but it will do just fine at distributing the load to the frame.
Aluminum has a softer surface and will scratch easier. I'm guessing the Aluminum F-150 will come with a bed liner from the factory.
Including the Honda Ridgeline? I thought that was an exception. In any case, you're mostly right, and that design is unlikely to change. Folks who actually use trucks in their work often bolt on various different styles of body: contractor bodies with large storage cabinets on the sides, enclosed van-like boxes, dumping beds, etc.
But frames can certainly be made of aluminum. The East company, which makes flat-bed and dumping trailers for semis, makes frames from aluminum. An unloaded, aluminum-framed flat-bed is very noticeable for its pronounced arch.
The scratchable surface of the bed will be paint, just as in the steel models.
The Honda Ridgeline is generally classified as a "sport utility truck", a category in which you'll also find vehicles like the Chevrolet Avalanche and Ford Explorer Sport Trac. It's basically an SUV (which are commonly unibody) without the rear enclosure. The distinction is that their primary design purpose is aligned more with that of an SUV than that of a pick-up truck.
I'm not aware of any true pick-up that uses a unibody design, and probably for the reasons you've stated.
52 comments
[ 2.1 ms ] story [ 116 ms ] threadOtherwise, I'd welcome not only the weight reduction, but the avoidance of rust and body rot.
[1] http://www.caranddriver.com/reviews/2007-audi-s8-long-term-r...
http://www.motormobiles.de/motor/a2i.jpg
The model was too expensive to produce and was cancelled by Audi in 2005. No aluminum Audis after that except some sport models. It's sort of a hidden gem.
To an outsider, making a big pickup truck from aluminum is like creating a paperweight out of some expensive lightweight material. Isn't the whole point of a pickup to most people (not all) being imposing and bulky? They even mention the 5000 pound weight in advertising, I assume they try to impress that it weighs a lot.
Due to aluminum?
> Isn't the whole point of a pickup to most people (not all) being imposing and bulky?
This is a whole discussion in itself. Modern pickups, to my eyes, look more like cartoons of pickups. The manufacturers (in my mind, especially Nissan and Ford) go out-of-their way to add big, chunky fenders and grills and such. It must sell. And small trucks are disappearing: Ford's Ranger is gone in the US market, and Toyota's Tacoma is now as big as the F150 of a decade or two ago.
Then the rear brakes also had to be fixed for the yearly checkup, normal wearing parts. And the internal heater had a connection problem, discovered when it started being cold enough that it was used (it's an aftermarket job anyway, to connect the car to an electricity outlet and warm up the engine block with a resistor and the interior with a resistor+fan).
I've had the car for six months and from rough memory, spent maybe 400 euros for maintenance.
Aluminum damage to the structural (sub)frame is a whole different beast than in the (non-structural) body panels. Aluminum work hardens when bent. When it hardens it become brittle and can crack from stress and vibration. Any damage has to be completely replaced with fresh metal.
Corrosion is still an issue with aluminum though it tends to self-protect itself. If you really want to mess up something aluminum add some mercury..
Disclaimer: Truck !== Good in Snow
On the flip side: how will the ever present salt affect the aluminum body?
All metals will corrode in the presence of salts. Though aluminum does not exhibit rusting like steel does, it will develop a chalky film and pitting in the metal surface when exposed to salt for long periods. I believe that this is aluminium oxide.
Some reading: http://www.boatingmag.com/how-to/maintenance/protecting-alum...
If I still lived in a state that used salt, I would follow the precaution of getting a year round carwash pass and going once a week. Plus, a good underbody coating works well.
1) put them over the back wheel, NOT loose in the bed so they slide. Rope or bungee cords are your friend.
[1] http://www.ford.com/trucks/f150/specifications/view-all/
In other words, less weight + smaller tire == same snow bite. Smaller tire? Cheaper tire. Smaller tire? Less rolling resistance. Lighter spare tire.
Lighter truck? Better gas mileage, better stopping, better cornering. If there is a 1000 lbs less to stop on the snow, that will make a huge difference.
Too many people think that their all-season tires can do everything. They can do everything, but they don't have the dry grip that summer tires do in warm weather, and they don't have the aggressive siping, channels and the tread compound for ice and very cold air temperatures of winter tires. All season tires do everything far worse than their specialty counterparts do, and it demonstrates itself the most every winter.
I drive lightweight RWD sports cars all year round, and we get plenty of snow in Boston. Never have had an issue with winter tires, and sometimes I deliberately seek out empty unplowed parking lots just to have extra fun in.
Snow tires are pretty cheap compared to body work too ;)
This is Ford's flagship vehicle. It cannot just sell well, it must put up amazing numbers. Its the iPhone of the car world.
1) the F-150's gas mileage isn't stellar, but it does even out when hauling.
The rollout of the EcoMod twin-turbo six-cylinder in the F-150 gives me some faith that they're not the usual run-of-the-mill idiots.
There seems to be a lot of FUD around the new F-150, and as a European, it's hard not to see the similarities with U.S reactions to small turbocharged engines, and smaller vehicles in general.
* https://en.wikipedia.org/wiki/Land_Rover_Series
The 2013 Range Rover has a complete aluminum body (skin and structure), with a 700lb weight reduction for US models.[1]
1. http://www.caranddriver.com/news/2013-land-rover-range-rover...
* Various differences among models some have steel roofs, doors etc.
But to give potential critics some credit, aluminum can be made very thin, like a beer can, in which case it is flimsy. It can also be made thicker, like the aluminum siding of the 60s and 70s, in which case it may still ding easily and lose its appearance.
The bicycle business moved to aluminium a generation ago. For at least a decade carbon fibre has been the material of choice for road bikes. Nowadays if you are from the school of 'steel is real' then you are going to have to buy a cheap 'bicycle shaped object', get something custom handmade or go for something deliberately hipster-retro.
Clearly there have been aluminium bodied cars for some time, even a 'truck' if you count the Land Rover. However, there is aluminium and there is aluminium. I suspect that the new Ford truck has a bit more to it than the Land Rover (or even the Audi A2) has.
In the bike business there is 6 series aluminium and 7 series aluminium, to name the most popular alloys. The original aluminium frames were welded together tubes, for a while 'bonding' was experimented with but that proved to be unreliable. The current state of the art is 'hydroformed' aluminium, welded. The 'hydroformed' frames are works of art, with the metal where you need it for strength, the grain structure also aligned for strength. The tubes are anything but plain cylinders and much more useful for design than was possible in the days of steel.
Does anyone have any more technical information on what the processes and alloys are going to be on this new-fangled truck?
Not entirely. http://surlybikes.com/
Steel is still cheaper, easier to fix, and more comfortable.
You might consider this to be in the second category, but here is a high-end bicycle maker that does exclusively steel frames: http://www.rodcycle.com/
Here is their advocacy for steel frames: http://www.rodbikes.com/articles/steel.html
Without the maganese this would be a series 5 aluminum according to the alloy grade comparison I found.[2]
1. http://en.wikipedia.org/wiki/Birmabright#cite_note-Camm.2C_B...
2. http://www.practicalmachinist.com/vb/general/aluminium-alloy...
I have two areas of expertise on this matter. First, I was on UW-Madison's competition-winning FutureTruck team about 10 years ago. We were, IIRC, the only team of about 15 other universities that replaced our competition car's (a Ford Excursion) entire frame with aluminum. In addition to replacing many other steel parts/assemblies with aluminum equivalents, we managed to bring the newly parallel hybrid SUV under stock weight... despite adding a large battery pack and motor. The thing I learned from this experience was: even though aluminum has about 1/3 the density of steel, your parts end up being about 50–55% of the steel weight because you need to add more aluminum to maintain equivalent strength. Basically, given the same tensile strength properties of a part, an aluminum one will be about half as heavy.
Second, I worked as a payload mechanical engineer for a number of spaceflight systems. Suffice to say, our base material for consideration was aluminum. Sure, we deferred to steel for certain applications (e.g., ball bearings, rat cage bars, fasteners, etc) and to myriad materials in others, aluminum was the standard. It has a tremendous strength/weight ratio, can be alloyed in many different ways to get different characteristics, is non-magnetic, is relatively cheap, and can have a number of interesting surface coatings applied. About the only major systemic problem aluminum has is that it is difficult to weld. Not impossible, as my FutureTruck experience tells me, but difficult. It didn't matter to us, though, since NASA generally frowns upon welded joints anyway. Too much strength variation due to heat stress and potential for FOD if not ground properly.
Anyway, I've been waiting for the auto industry to catch up to a bunch of college students for 10 years now. Nice to see one of the Big Four finally getting it. And cheers to the smaller car companies that have been doing it for years.
Corrosion is more commonly known as rust, but that's technically reserved for steel (or, more accurately, iron) oxidation. Aluminum certainly corrodes, but it corrodes into aluminum oxide, or alumina, which is actually a ceramic that is stronger than aluminum. In fact, good luck using aluminum without a coating of alumina... it naturally occurs on the surface of atmospherically exposed aluminum. As a result, when a chunk of aluminum is broken off of a larger piece, the material almost immediately forms a protective layer of alumina. It's almost like aluminum self-heals in the presence of oxygen.
Galvanic corrosion occurs when dissimilar metals come into contact amidst an electrolyte solution. In the case of vehicles, that's usually seawater/sea-mist or salted winter roads. While saltwater is also responsible for accelerating normal corrosion, it also plays a part in galvanic corrosion. So yes, having aluminum and steel touching is a recipe for galvanic corrosion, but galvanic corrosion is not black-and-white. Each metal has an anodic index; a high or low anodic index doesn't matter all that much. What matters is the difference between the anodic indices of the touching metals. For aluminum and steel, that difference is quite small, so galvanic corrosion isn't a huge issue, but it's not negligible either.
Galling occurs when the sliding friction of two parts, say a screw and its threaded mate, results in plastic deformation, usually in the more ductile of the two pieces. This generally doesn't come into play in the construction of a vehicle because many parts are attached either by welding or by a bolt-nut combo. Choosing the correct materials for the bolts and nuts (basically, just use hardened, but not stainless, steel) gets rid of this concern in most cases. In cases where one must screw a steel fastener into a threaded aluminum piece, a helical insert is usually prescribed. While many manufacturers make these, we typically used Helicoil for spaceflight ops because they're tested and rated for spaceflight (batch traceability, proper composition docs, etc).
[1] https://en.wikipedia.org/wiki/Galvanic_corrosion
[2] https://en.wikipedia.org/wiki/Galling
http://www.youtube.com/watch?v=ES-JVFNwFV4
For all that work you'd think these days carbon fibre would be just as good, economically-wise.
If the bed interior is aluminum, they will have to increase the thickness compared to steel, but it will do just fine at distributing the load to the frame.
Aluminum has a softer surface and will scratch easier. I'm guessing the Aluminum F-150 will come with a bed liner from the factory.
Including the Honda Ridgeline? I thought that was an exception. In any case, you're mostly right, and that design is unlikely to change. Folks who actually use trucks in their work often bolt on various different styles of body: contractor bodies with large storage cabinets on the sides, enclosed van-like boxes, dumping beds, etc.
But frames can certainly be made of aluminum. The East company, which makes flat-bed and dumping trailers for semis, makes frames from aluminum. An unloaded, aluminum-framed flat-bed is very noticeable for its pronounced arch.
The scratchable surface of the bed will be paint, just as in the steel models.
I'm not aware of any true pick-up that uses a unibody design, and probably for the reasons you've stated.