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Hydroforming and new welding methods help reduce vehicle weight

New CAFE standards have automakers reaching for any technology they can find to help improve fuel economy. Many manufacturers are going to electric vehicles or hybrids to increase their overall fleet mileage averages. The problem with focusing only on hybrids and electric vehicles, however, is that most consumers aren't in the market for that type of vehicle.

On traditional gasoline-powered vehicles, automakers are increasingly turning to weight savings as a way to help improve fuel economy. The lighter a vehicle can be made, the less weight the engine has to push or pull around and the less fuel it uses because engines could be made smaller without sacrificing performance.

Some automakers are even turning to removing some features of cars such as CD players and the spare tire to reduce weight according to the Detroit News. Both General Motors and Ford are turning to new processes in vehicle assembly to help remove weight from the body of mainstream vehicles.

2013 Ford Fusion
Many automakers are using aluminum rather than steel to help reduce the weight of their vehicles. Hoods, trunks, and lift gates as well as door skins are commonly made from aluminum today. Ford is also experimenting with carbon fiber on the Focus.

Switching to lighter materials isn't the only way automakers are going about reducing the weight of the vehicles they produce. They're also reducing weight by changing the manufacturing processes used. Ford, for instance, is using hydroforming on the steel structural pillars of its 2013 Fusion.

One of the big benefits of hydroforming is that it allows the forming of complicated and larger parts that don't need to be welded together. Traditional stamping produces multiple parts that have to be welded at joints. Those joints are points of weakness and add weight. Using hydroforming, rather than other forms of stamping, sheds 18 pounds from each car by eliminating the additional welds.

GM is also doing its part testing a thermal-forming process for lightweight magnesium that weighs 75% less than steel. GM also plans to use a patented welding technology to allow the company to integrate more aluminum into automotive bodies by saving the company from using rivets to join aluminum body panels. The use of the welding process rather than rivets will cut nearly 2 pounds from parts such as hoods, lift gates, and doors.

Source: Detroit News

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RE: Bout time
By Solandri on 10/25/2012 12:05:03 PM , Rating: 2
Keep it going, there are so many improvements that can be made in cars that haven't been explored yet.

It was never an issue of improvements not being explored. When selecting a material for a part, you have multiple dimensions to consider: cost, weight, strength, stiffness, fatigue strength (durability), fracture toughness, ease of manufacture, energy absorption under deformation, and probably a few more I can't think of off the top of my head.

Steel has just about the highest strength-to-cost ratio of any material. That's why it's so popular. Aluminum, carbon fiber, and magnesium alloy all have better strength-to-weight ratios than steel, but are ridiculously expensive compared to steel. They are also inferior to steel in many of the other dimensions I've listed, requiring more material, more expensive tooling, and/or resulting in shorter lifespan.

If you want to mandate higher fuel economy, then understand that it'll come with a price. Steel was used heavily because the auto industry optimized for cost and it offered the most strength for least cost. Now that the industry has to optimize for something other than cost, cost will go up. You wanna know what happens to an industry when it optimizes for weight instead of cost? Just look at prices in aerospace. The metal push-back rod used to back a plane out of a gate broke on a flight I was just on. The pilot reported that it costs $250,000.

Your $1000 high-end bike uses aluminum and magnesium alloy. Your $3000 racing bike uses carbon fiber. Your $250 everyday bike is made of steel. If you really want to draw the bike analogy, then you're proposing turning the $25,000 family sedan into a $100,000 to $300,000 family sedan all in the name of using lighter materials. Does that really make sense?

RE: Bout time
By zephyrprime on 10/25/2012 12:32:00 PM , Rating: 2
aluminum and magnesium have worse strength to weight ratios than steel. Especially magnesium which is very weak.

RE: Bout time
By FITCamaro on 10/25/2012 1:30:37 PM , Rating: 2
He didn't claim that they were close to steel.

RE: Bout time
By TheDoc9 on 10/25/2012 1:47:35 PM , Rating: 2
That's what I was thinking, these materials definitely don't make cars safer even if they manage to pass a few known crash tests that they can plan and design for.

Of course, the cars will be more expensive as well and it's acceptable because we're saving the environment, right?

RE: Bout time
By madtruths on 10/25/12, Rating: 0
RE: Bout time
By messele on 10/25/2012 4:45:41 PM , Rating: 1
Where on earth do you people get your information from? Aluminium and Magnesium have a massive Strength / Weight ratio advantage over steel for most applications.

The main disadvantage of magnesium is it's reactivity in the event of a fire.

RE: Bout time
By 91TTZ on 10/25/2012 4:49:45 PM , Rating: 2
Where on earth do you people get your information from? Aluminium and Magnesium have a massive Strength / Weight ratio advantage over steel for most applications.

Not as much as you'd think. Aluminum suffers from metal fatigue pretty badly, so you can can't really take full advantage of the higher strength/weight ratio. You have to design around its fatigue limit which is pretty low, which make it roughly the same as steel.

RE: Bout time
By Jeffk464 on 10/25/2012 11:39:53 PM , Rating: 2
First of all nobody uses pure steal which is an alloy or pure aluminum. Basically almost all metals used in manufacture are alloys which change the properties of the pure metal a lot. If you look at aerospace aluminum it doesn't have a short fatigue life or readily corrode like pure aluminum. The air force is flying aluminum airframes that are over 50 years old and there is far more flexing in a plane's wing than you will see anywhere on a car. And of course aluminum is stronger by weight than steal otherwise planes would be built out of steal.

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