R-34
07-14-2003, 11:26 PM
Let's face it, the stuff is everywhere. It's hard to make it through a waking moment of modern life without encountering something made of plastic–from your toothbrush to your telephone to your TV set. And if Chrysler Corp. is successful, you may be able to include your next new car on that list of life's plastic necessities.
Plastic and cars are nothing new, of course. There's a lot of plastic in, on and scattered around whatever car or truck you're driving now. And there have been a number of cars with plastic body parts–bumpers and even fenders. But here we're talking about an entire body made of plastic. We're not talking about a fiberglass body, like a Corvette. Nor are we talking about a body made of sheet-molded composites attached to a space frame, like a Saturn.
No, we're talking about a vehicle with essentially its entire body made of injection-molded polyethylene terephthalate–which you probably know in one of its more familiar forms, soda pop bottles.
Chrysler enlisted the expertise and help of key suppliers–firms that have experience in dealing with the various materials and methods used in building things of injection-molded plastic. No one of them had ever dealt with anything as big or complex as a car, however.
Of course, just because something's made of essentially the same stuff as a pop bottle doesn't mean it has the same lines as a 2-liter Dr. Pepper. Consider this slinky, sexy Plymouth Pronto Spyder. Chrysler built it to show the public just how far plastic has come. Revealed back in January at the North American International Auto Show in Detroit, the midengine, 225-hp 2-seater is a serious runner. A serious plastic runner.
Before the svelte Pronto Spyder showed itself, though, Chrysler began developing this manufacturing technology on a more modest scale, with its Composite Concept Vehicle, or CCV. This basic transportation device was shown at last year's Frankfurt Auto Show. The CCV may lack the complex body shapes of the Pronto Spyder or the ESX II, an Intrepid-size concept car also made of injection-molded plastic and seen at auto shows. But the CCV has all the manufacturing breakthroughs of its siblings.
Chrysler's engineers–and their supplier partners–designed the CCV to have a structure that consists essentially of only four body elements: left and right exteriors and left and right interiors. That's it. These then get glued together to form the entire body shell–less doors, hood and trunklid. This completed body is then attached to a rolling chassis.
Injection-molded plastic has been used in auto manufacturing for years. But never before had any company successfully attempted to produce anything nearly as large or complex as one half of a body's interior or exterior. Small wonder when you consider the size of the equipment needed to mold that large a piece of plastic. A monster-size, 9000-ton molding machine injects the thermoplastic polyester resin into the body molds. The molds themselves are room-size 160-ton units.
The key to Chrysler's success in molding such huge pieces of plastic was computer modeling. This helped them devise the sophisticated sequence of gate openings and gas injections that need to take place rapidly within the mold during the injection process.
Amazingly, the cycle is complete and the body sections are done in only 3 minutes. That means that they are shaped, structurally sound and cool, and ready to assemble. They're molded their final color, and any textured surfaces come out of the mold looking and feeling the way they will in the showroom.
Among other things, this means that there is no need for a paint shop, since the cars don't need to be painted–a huge savings of money, space and time.
The sections are attached to each other with adhesive, and once cured the body is bolted and glued to the chassis. The rolling chassis carries the drivetrain, suspension and steering. In the case of the Pronto Spyder, that's a supercharged 2.4-liter, 5-speed manual and 4-wheel independent-strut setup. All that's left is interior trim, doors and decklid. There's less need for insulating material since the molded plastic is thick enough to act as a sound deadener. There's no need for interior trim pieces to hide fasteners–because there are no fasteners.
Far fewer parts are needed. Chrysler says that even with the requirement for a separate metal frame beneath the plastic body, the injection-molding method reduces the total number of parts needed to build a car by about 75%. The time savings is almost as astounding–it takes only about one-third the amount of time it would to build an equivalent car using traditional methods.
In addition to the time and cost savings, there's a real environmental boon with the process. Since the plastic used is so similar to that used in pop bottles, the car's body is eminently recyclable–and recycled bottles and other items can even be used in the mix.
Despite these advantages and all of this promise, there are still some problems to be resolved before you can drive home in a plastic car. One issue is whether a plastic car can meet rigid crash-test standards without a steel substructure. Second, the long-term durability of a large, glued-together plastic body has not yet been proven.
But perhaps more difficult to answer than the engineering questions are the marketing ones. You see, though the molding process delivers a car of the desired color, it has a matte finish, not a glossy one. And the truth is, people are used to shiny new cars.
http://popularmechanics.com/automotive/auto_technology/1998/7/plastic_chrysler_bodies/images/1026_2-01.jpg
http://popularmechanics.com/automotive/auto_technology/1998/7/plastic_chrysler_bodies/images/1026_3.gif
popularmechanics.com
Plastic and cars are nothing new, of course. There's a lot of plastic in, on and scattered around whatever car or truck you're driving now. And there have been a number of cars with plastic body parts–bumpers and even fenders. But here we're talking about an entire body made of plastic. We're not talking about a fiberglass body, like a Corvette. Nor are we talking about a body made of sheet-molded composites attached to a space frame, like a Saturn.
No, we're talking about a vehicle with essentially its entire body made of injection-molded polyethylene terephthalate–which you probably know in one of its more familiar forms, soda pop bottles.
Chrysler enlisted the expertise and help of key suppliers–firms that have experience in dealing with the various materials and methods used in building things of injection-molded plastic. No one of them had ever dealt with anything as big or complex as a car, however.
Of course, just because something's made of essentially the same stuff as a pop bottle doesn't mean it has the same lines as a 2-liter Dr. Pepper. Consider this slinky, sexy Plymouth Pronto Spyder. Chrysler built it to show the public just how far plastic has come. Revealed back in January at the North American International Auto Show in Detroit, the midengine, 225-hp 2-seater is a serious runner. A serious plastic runner.
Before the svelte Pronto Spyder showed itself, though, Chrysler began developing this manufacturing technology on a more modest scale, with its Composite Concept Vehicle, or CCV. This basic transportation device was shown at last year's Frankfurt Auto Show. The CCV may lack the complex body shapes of the Pronto Spyder or the ESX II, an Intrepid-size concept car also made of injection-molded plastic and seen at auto shows. But the CCV has all the manufacturing breakthroughs of its siblings.
Chrysler's engineers–and their supplier partners–designed the CCV to have a structure that consists essentially of only four body elements: left and right exteriors and left and right interiors. That's it. These then get glued together to form the entire body shell–less doors, hood and trunklid. This completed body is then attached to a rolling chassis.
Injection-molded plastic has been used in auto manufacturing for years. But never before had any company successfully attempted to produce anything nearly as large or complex as one half of a body's interior or exterior. Small wonder when you consider the size of the equipment needed to mold that large a piece of plastic. A monster-size, 9000-ton molding machine injects the thermoplastic polyester resin into the body molds. The molds themselves are room-size 160-ton units.
The key to Chrysler's success in molding such huge pieces of plastic was computer modeling. This helped them devise the sophisticated sequence of gate openings and gas injections that need to take place rapidly within the mold during the injection process.
Amazingly, the cycle is complete and the body sections are done in only 3 minutes. That means that they are shaped, structurally sound and cool, and ready to assemble. They're molded their final color, and any textured surfaces come out of the mold looking and feeling the way they will in the showroom.
Among other things, this means that there is no need for a paint shop, since the cars don't need to be painted–a huge savings of money, space and time.
The sections are attached to each other with adhesive, and once cured the body is bolted and glued to the chassis. The rolling chassis carries the drivetrain, suspension and steering. In the case of the Pronto Spyder, that's a supercharged 2.4-liter, 5-speed manual and 4-wheel independent-strut setup. All that's left is interior trim, doors and decklid. There's less need for insulating material since the molded plastic is thick enough to act as a sound deadener. There's no need for interior trim pieces to hide fasteners–because there are no fasteners.
Far fewer parts are needed. Chrysler says that even with the requirement for a separate metal frame beneath the plastic body, the injection-molding method reduces the total number of parts needed to build a car by about 75%. The time savings is almost as astounding–it takes only about one-third the amount of time it would to build an equivalent car using traditional methods.
In addition to the time and cost savings, there's a real environmental boon with the process. Since the plastic used is so similar to that used in pop bottles, the car's body is eminently recyclable–and recycled bottles and other items can even be used in the mix.
Despite these advantages and all of this promise, there are still some problems to be resolved before you can drive home in a plastic car. One issue is whether a plastic car can meet rigid crash-test standards without a steel substructure. Second, the long-term durability of a large, glued-together plastic body has not yet been proven.
But perhaps more difficult to answer than the engineering questions are the marketing ones. You see, though the molding process delivers a car of the desired color, it has a matte finish, not a glossy one. And the truth is, people are used to shiny new cars.
http://popularmechanics.com/automotive/auto_technology/1998/7/plastic_chrysler_bodies/images/1026_2-01.jpg
http://popularmechanics.com/automotive/auto_technology/1998/7/plastic_chrysler_bodies/images/1026_3.gif
popularmechanics.com