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Car Tech: What are the pros and cons of plastic cars?

by wcunning CNET staff - 6/6/07 1:57 PM
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Post 16 of 419

An engineer's view

by AnotherEngineer - 6/6/07 9:21 PM In reply to: What are the pros and cons of plastic cars? by wcunning CNET staff

Cars have to become more fuel efficient. This can be addressed by improving engine efficiency (so they use less fuel) and/or by decreasing the weight of the car. Plastic and carbon-fiver panels are a given. You won't have a choice in the future.

Steel is easy for our auto makers to manipulate, but they will quickley learn to make carbon-fiber and fiberglass panels and strength members with the same efficiency.

They will also learn to build more efficient engines - electric and alternate fuel as well as gasoline powered. It's a new world and we are motivated. The bread line is not that far away!

Post 17 of 419

Unrecyclable

by mwooge - 6/6/07 10:53 PM In reply to: What are the pros and cons of plastic cars? by wcunning CNET staff

The main problem I see with plastic and composite car parts is that they can't be recycled. When the car goes bad, it'll be a big, bulky chunk of stuff to landfill.

Post 18 of 419

are you high?

by dstefani1970 - 6/20/07 9:06 PM In reply to: Unrecyclable by mwooge

you don't think plastic is unrecyclable? smoke another one dude

Post 19 of 419

Plastic or Metal....Protection

by Shirley97128 - 6/7/07 1:17 AM In reply to: What are the pros and cons of plastic cars? by wcunning CNET staff

Due to a recent accident, a guy was going about 50mph in a residential area and ran the stop sign, I was going 20mph and was in his way. The only thing that saved my life was the strudy build of my GMC Van and the Angel watching over me. I had been considering a smaller car for better gas mileage. Not any more.
Beaten & Broken, but alive,
Shirley

Post 20 of 419

(NT) Qualtiy, Not Material...

by alexanderpas - 6/7/07 5:08 PM In reply to: Plastic or Metal....Protection by Shirley97128

Post 21 of 419

But it is the material!!

by Andy77e - 6/9/07 11:57 AM In reply to: (NT) Qualtiy, Not Material... by alexanderpas

Come on people! What are ya thinking?!

You want to tell me it isn't plastic verses metal, that somehow "it's the quality" that makes a difference? Bull! I roll around in an 82 Buick Riviera. It's a small civilian legal tank.

I've been hit twice. Both times there was substancial damage to the other car, both times I didn't even have a scratch. One was a Honda Civic. He hit me so hard, that the whole front end of his car was bashed in like a bull dogs face. Not a scratch! Nothing! My chrome bumper had nothing on it to even indicated it had ever been hit!

How in the WORLD do you think plastic is safer than metal?! That's JOKE!

Three years ago there was a story about a guy in an large SUV, suburban I think. It rolled off a 30 foot drop, landed upside down. Guy climbed out and walked home. You think you'd survive that in a plastic car? Not a snowballs chance in hell, sorry!

Post 22 of 419

ROLL CAGE

by edge_bit - 6/20/07 9:24 PM In reply to: But it is the material!! by Andy77e

Um, I have a feeling plastic cars would be sturdier because they would have full roll cages rather than just a unibody eggshell protecting the passengers.

In an accident, high end unibody cars don't crush in the passenger compartment even a tiny bit.

Low-end unibody cars crush the passenger compartemnt all over.

Even a cheap plastic car with an industry standard roll cage will probably save your ass better than a tin-can unibody.

Sure, it's not the same as an SUV. It will likely be just about as good if not better, though.

Say you roll on the roof. Okay, you have half the curb weight resting on twice as strong of a roof. Remember these are not the plastics your kids play with but real, thick, high-quality plastics.

Anyway... I think most people see this idea and think of it as rolling around town in their kids' "Power Wheels".

NO! Not even close...

Post 23 of 419

Plastic versus Steel

by LeeWilliams - 6/20/07 11:18 PM In reply to: ROLL CAGE by edge_bit

Some years ago when Corvettes were made with plastic I had a friend lose his life in an accident, because the car literally exploded when rolling and wound up i lots of small pieces. Since then I have had serious doubts about plastic. Also, recently saw a small Honda accord or Del Sol (cant remember which) that got hit by a 10 yr older 1/2 ton pickup and it was destroyed as well, with minor damage to the truck. Just a couple of incidents, but if this is good engineering..... I hate to see everything go to plastic.

Post 24 of 419

Corvettes are not plastic

by MudSnow - 6/21/07 7:47 AM In reply to: Plastic versus Steel by LeeWilliams

Corvettes have never been made out of plastic. They are made out of fiberglass, which is a totally different thing. Plastic is flexible, not brittle.

Post 25 of 419

Both correct

by carolina1 - 6/21/07 8:17 AM In reply to: Corvettes are not plastic by MudSnow

Fiberglass is only the reinforcing for the resin used. The resins used although not technically a plastic are in all practical terms from the same family and created by similar methods.
All plastics used in cars are filled to some extent to strengthen the material. Fiberglass strands are just one option over other fillers.

Post 26 of 419

fiberglass

by wcoffey81 - 6/21/07 10:36 AM In reply to: Both correct by carolina1

up until the late 70's the vette was still a fiberglass product. which is a polyester based resin reinforced with spun glass fibers. when the bodies changed in early 80's the went to a product called SMC (sheet moulded compound). new replacement panels for the older models are now made out of smc.
smc was really cool! it looked like a packed down furnace filter with an oily feel because of the resin which was already in it. the only size limit they had was because of the width of the mill used to produce the raw product. instead of adding a hardner to the resin, like in all polyester based systems, what was in SMC could be heat cured. one is exothermic and the other endothermic, in other words one produced heat during the cure and the other required the application of heat to cure. under heat and pressure they could form just about anything and the dies hardly ever needed maintainance unlike the dies used to stamp steel panels.

Post 27 of 419

Vettes have fiberglass bodies

by stevenhs - 6/22/07 10:08 PM In reply to: fiberglass by wcoffey81

Corvettes still have fiberglass bodies and always have since the beginning. There is not a year that they did not.

Post 28 of 419

fiberglass??

by wcoffey81 - 6/23/07 12:04 PM In reply to: Vettes have fiberglass bodies by stevenhs

if you are correct, why did GM send me to the tech center to be trained and certified in repairing the Corvette SMC panels???? starting with the body change in,i think, 1986 ALL CORVETTES WERE MADE WITH SMC PANELS!! all NOS panels for older models were also shifted to SMC. i still have my training manuals and certificates from all of my training at the GM tech center in Warren Mi. and Cleveland Oh. so unless you have some top-secret memo that they forgot to give me.......
take a sander to it, go down the the bare SMC and wipe it with a damp rag. it will be dark grey with a swirly pattern to it = SMC.
a brownish/grey color and you can see the full pattern of the fibers = polyester based fiberglass.
steven, i know these forums are a good to express ourselves but you shouldn't make blanket statements like you did. i could teach you a lot but you are going about it the wrong way. ask me how i know something or ask me if i'm positive about it but don't call me a liar!

Post 29 of 419

fiberglass2

by wcoffey81 - 6/25/07 6:59 AM In reply to: fiberglass?? by wcoffey81

folks i am sorry! i let a troll get to me and i reacted poorly

Post 30 of 419

Try Google before posting

by make_or_break - 6/26/07 3:07 PM In reply to: Vettes have fiberglass bodies by stevenhs

Fiberglas-bodied Vettes have been consigned as a thing of the past (thankfully) with the last three generations of Corvettes.

As for plastics: as the technology stands now, I'll personally stay away from them in any of my future cars, particularly in the areas subjected to structural and severe impact loads. I recall some very vivid and catastrophic accidents in F1 where certain teams switched from titanium and other aluminum alloy structural members to carbon fiber and/or Kevlar. Accidents that invariably happened in the course of racing that occurred after the change were much more dramatic and injurious to the drivers.

The current state of technology with polymer-type structural members just isn't up to the toughness of metals; polymer-based materials more often than not literally shatter and explode upon impact rather than deform and absorb the collision energy like metals do. The same likely goes for long-term fatigue of materials as well. Moreover, subject polymers to engine and exhaust heat and environmental exposure such as UV...sure recipe for degradation and failure.

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