- Posted on Tuesday, June 6th, 2006 at 2:47 pm
How the Pontiac Solstice and Saturn Sky Got their Seductive Curves
Tres Kline
Director, Body Manufacturing Engineering Press Center
Almost all the curvaceous body panels on the Pontiac Solstice and Saturn Sky are produced via sheet metal hydroforming, a first for a production vehicle. A relatively new process that uses water pressure to help form the desired panel shapes, sheet metal hydroforming is used to create the unique clamshell hood, outer door panels, rear deck lid, and quarter panels.
Sheet metal hydroforming of exterior body panels has seen limited use in other markets around the world, predominantly for low-volume specialty aftermarket panels. The body panels in these roadsters represent the first exterior application of the technology in a mass-produced automobile.
Sheet metal hydroforming (also known as counterpressure forming) allows much deeper draw — or depth of the component — necessary for creating panels with complex curves. Many of the Solstice and Sky body panels could not have been formed by conventional stamping methods.
Although more time consuming than conventional draw stamping, sheet hydroforming requires fewer die sets, which reduces tooling costs. The sheet metal hydroforming process uses hydraulic counterpressure to press a blank panel onto the die. Counterpressure builds as the die presses the blank downward into the water tank. The compressed water forces the blank onto the die, forming the shape of the panel.
Because pressure is spread more evenly onto the blank, sheet metal hydroforming helps to reduce the coefficient of friction generated in the forming process, which leads to a more uniform panel thickness than conventional draw stamping. More uniform panel thickness improves the chances for successful forming, particularly when creating the complex shapes you see on the Solstice and Sky roadsters.
6 Comments
Nathan Lawless
Hydroforming is great and I’m glad to see that GM is bringing it to the mass market process. That being said, when can we expect GM to further lead the pack and start hydroforming panels on production sedans? Certainly it can’t do anything but help the styling. The current sedan lineup from Chevy looks awful, but cars like the G6 and the new Saturn Aura give hope. Also, can hydroforming help to lighten these cars b/c they continue to get heavier as the years go by. As any engineer will tell you, the heavier the car for a given engine, the worse the performance and fuel economy of said vehicle.
josh
They are nice, but where is the Buick Velite?
gtjeff
Which has lower tooling costs, hydroformed panels or plastic panels? If possible could you please provide a percentage difference.
It would be fair to mention that hydroforming isnt the only way to produce complex curves in body panels. The Corvette’s fenders which are made out of plastic on the base model and carbon fiber on the Zo6 are just as arched as those on the Sky.
getalifeagain
This is a very interesting process, but is it cost effective? Because if it is, why not use it on all vehicles?
Robotech
It is still a relatively new process. Depending on cost effectiveness you may see a transition to hydroforming body panels. GM has been doing it for a while on their truck chassis and I believe Ford or Dodge have a partially hydroformed truck chassis too but are fairly behind GM’s development and deployment of this technology.
Edwin
The Velite should be a Cadillac Roadster. Cadillac needs a verion of it anyway.
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