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Post by the light works on Aug 3, 2014 15:11:10 GMT
Doing some reading, part of Saturn's problem was the cost of the plastic panels. They were made from a combination of ABS and polycarbonate plastic that had the same color though the thickness of the plastic. This PC/ABS had a bad reputation of not flowing well in molds and having runs and flows that messed up the color. This lead to high loss rates that drove the prices up. Also, because you have to run different plastic mixes for each color of car, you high production costs because you have to maintain complete inventories of body panels for every color. This also limits the colors you can make cars in. Thinking about the above, all the plastic bumper covers I have worked with other than my parent's Saturn use a primer color plastic (usually black) that is than painted to match the rest of the car's body. So at least one thing that could be done for an all plastic car today to reduce costs is to skip the molded color panels and just have one panel set that is painted to whatever color you what. the advantage to the molded color panels was the high resistance to damage (as in parking lot dings). - I had assumed the panels were essentially vacuum formed, which would have made them more economical than the molding process you are saying they used. I don't know whether the Smart is painted or molded in color. presumably a good middle ground would be if a carmaker could pioneer a process where a molded in color overlay was vacuum formed to a base color structural panel.
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Post by OziRiS on Aug 3, 2014 18:07:36 GMT
Doing some reading, part of Saturn's problem was the cost of the plastic panels. They were made from a combination of ABS and polycarbonate plastic that had the same color though the thickness of the plastic. This PC/ABS had a bad reputation of not flowing well in molds and having runs and flows that messed up the color. This lead to high loss rates that drove the prices up. Also, because you have to run different plastic mixes for each color of car, you high production costs because you have to maintain complete inventories of body panels for every color. This also limits the colors you can make cars in. Thinking about the above, all the plastic bumper covers I have worked with other than my parent's Saturn use a primer color plastic (usually black) that is than painted to match the rest of the car's body. So at least one thing that could be done for an all plastic car today to reduce costs is to skip the molded color panels and just have one panel set that is painted to whatever color you what. I worked at an auto parts warehouse a while back and all the bumper panels we got home were either black or white, depending on the manufacturer, so obviously someone has learned from that mistake. <SNIP> presumably a good middle ground would be if a carmaker could pioneer a process where a molded in color overlay was vacuum formed to a base color structural panel. Should be easy enough to do. You're thinking something like a stick-on decal, but for an entire bodypanel, right?
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Post by Cybermortis on Aug 3, 2014 19:19:53 GMT
Another problem is that plastic degrades when exposed to sunlight. This isn't a problem for a new car, but ten years on owners might end up having to replace all the paneling on their car. It might also result in the paneling becoming so brittle that the shell might shatter in an impact. At best this might triple repair costs for otherwise minor accidents and at worse could potentially result in the occupants being showered by wall of sharp edged plastic shards in stronger impacts.
They'd get dirty and work even less efficiently, the added weight more than offsetting any additional power you might initially get.
This is one of the overlooked problems with solar-powered cars - you have to keep them VERY clean or the cells stop working.
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Post by ironhold on Aug 3, 2014 22:56:05 GMT
Another reason to fear plastic body panels: Gold Plastic Syndrome (slightly NSFW). In a nutshell, certain plastics used by toy maker Hasbro since 1986 have shown an alarming tendency towards being brittle, such that some samples have broken into pieces while still in the original packaging because the plastic essentially decomposed.
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Post by Cybermortis on Aug 3, 2014 23:41:10 GMT
That is for a rather specific type of plastic, and one that is unlikely to end up being used on motor vehicles.
However it does show that plastics can be unpredictable even when stored under ideal conditions. Having plastic panels on cars exposes the plastic to stresses, chemicals and environmental conditions that no manufacturer could realistically test to see what effect they may have, let alone for the working life of a car - figure 20-30 years as the average life of a car before it becomes uneconomical to repair and maintain.
Cars have to be designed so that they can survive and continue to work in conditions ranging 40 degrees centigrade and months if not years of direct sunlight, down to six months of sub-zero temperatures. And all the time the vehicle is being exposed to pollutants from other vehicles and stresses as the car moves and flexes.
One of the last things a car maker wants is a story as to how one of their cars hit a pot hole and the entire paneling shattered.
Another aspect might be safety in case of fire. Metal doesn't burn, plastics might - and if it does burn you end up releasing a cloud of highly toxic smoke.
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Post by the light works on Aug 4, 2014 0:00:57 GMT
Doing some reading, part of Saturn's problem was the cost of the plastic panels. They were made from a combination of ABS and polycarbonate plastic that had the same color though the thickness of the plastic. This PC/ABS had a bad reputation of not flowing well in molds and having runs and flows that messed up the color. This lead to high loss rates that drove the prices up. Also, because you have to run different plastic mixes for each color of car, you high production costs because you have to maintain complete inventories of body panels for every color. This also limits the colors you can make cars in. Thinking about the above, all the plastic bumper covers I have worked with other than my parent's Saturn use a primer color plastic (usually black) that is than painted to match the rest of the car's body. So at least one thing that could be done for an all plastic car today to reduce costs is to skip the molded color panels and just have one panel set that is painted to whatever color you what. I worked at an auto parts warehouse a while back and all the bumper panels we got home were either black or white, depending on the manufacturer, so obviously someone has learned from that mistake. <SNIP> presumably a good middle ground would be if a carmaker could pioneer a process where a molded in color overlay was vacuum formed to a base color structural panel. Should be easy enough to do. You're thinking something like a stick-on decal, but for an entire bodypanel, right? I'm thinking of something about the thickness of blister packaging. (as well as the perceived indestructibility)
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Post by wvengineer on Aug 4, 2014 12:03:52 GMT
Cyber, considering just how common plastic bumper covers are,* I think we can safely say that long term UV exposure and fire risks are either non-issues or within acceptable risk levels. The process of painting the plastic or chrome overlays would go a long way to protecting the underlying plastic from UV damage. I could see the NTSB regulating some of the chemical components of plastic body parts to remove potential toxic fumes if it were to catch on fire, similar to the way plenum vs. non-plenum data cable is sometimes required for safety reasons.
* Can you find a normal consumer car that does not have plastic bumper covers? I think you have to go back to the 80's to find exposed metal bumpers.
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Post by Cybermortis on Aug 4, 2014 12:28:35 GMT
Cyber, considering just how common plastic bumper covers are,* I think we can safely say that long term UV exposure and fire risks are either non-issues or within acceptable risk levels. The process of painting the plastic or chrome overlays would go a long way to protecting the underlying plastic from UV damage. I could see the NTSB regulating some of the chemical components of plastic body parts to remove potential toxic fumes if it were to catch on fire, similar to the way plenum vs. non-plenum data cable is sometimes required for safety reasons. * Can you find a normal consumer car that does not have plastic bumper covers? I think you have to go back to the 80's to find exposed metal bumpers. The plastic covering on bumpers is designed to absorb impacts with pedestrians, with the metal beam under the plastic providing the strength to handle impacts with more solid things - such as cars or posts.
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Post by silverdragon on Aug 4, 2014 15:18:18 GMT
Plastic body panel's, as I learnt Young, are a waste of bloody money when it comes to accidental damage.
I have managed to break several parts on various vehicles, all plastic, that would have withstood a knock if they were Metal?.. Ok, so they are my own fault, I know, and beyond the range of accepted wear and tear. But some pratt put plastic Bumpers on a Mini... One low three foot fence post unseen from the back window later, I needed a replacement. A Chrome bumper would have just dented, and half hour with a heavy hammer to put back in shape?...
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Post by c64 on Aug 4, 2014 15:44:02 GMT
So with automakers needing ways to save weight, why not bring back the plastic? Almost all EU made vehicles are essentially plastic for anything that doesn't have to handle forces. Even the bumper "bars" are just plastic decoration and have no technical purpose at all any more. Except for the doors, this is almost everything which is real metal on this car, the rest is plastic which becomes attached later. The "front module" is mostly plastic except for a few structural metal parts. The idea is that if you bump your car into something, you can swap the "front module" to make the car "like new" again for a reasonable price. On the other hand, if the crash was more serious, a lot of important parts around the engine become destroyed and then the car is a write-off.
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Post by c64 on Aug 4, 2014 15:52:31 GMT
Here are modern cars with the plastic burned away or molten:
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Post by the light works on Aug 4, 2014 16:08:58 GMT
Plastic body panel's, as I learnt Young, are a waste of bloody money when it comes to accidental damage. I have managed to break several parts on various vehicles, all plastic, that would have withstood a knock if they were Metal?.. Ok, so they are my own fault, I know, and beyond the range of accepted wear and tear. But some pratt put plastic Bumpers on a Mini... One low three foot fence post unseen from the back window later, I needed a replacement. A Chrome bumper would have just dented, and half hour with a heavy hammer to put back in shape?... the way Saturn promoted their plastic body panels was to give the customer a baseball bat and tell him he could have a dollar if he put a dent in the car.
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Post by c64 on Aug 4, 2014 16:57:21 GMT
[quote author=" the light works" source="/post/45839/thread" [/quote]the way Saturn promoted their plastic body panels was to give the customer a baseball bat and tell him he could have a dollar if he put a dent in the car.[/quote] Nice, you can't make any dent in this kind of plastic. It will crack or at least show bright lines if you give it a good whack and then it still needs to be replaced or it might fall off while driving.
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Post by silverdragon on Aug 6, 2014 7:11:01 GMT
Plastic body panel's, as I learnt Young, are a waste of bloody money when it comes to accidental damage. I have managed to break several parts on various vehicles, all plastic, that would have withstood a knock if they were Metal?.. Ok, so they are my own fault, I know, and beyond the range of accepted wear and tear. But some pratt put plastic Bumpers on a Mini... One low three foot fence post unseen from the back window later, I needed a replacement. A Chrome bumper would have just dented, and half hour with a heavy hammer to put back in shape?... the way Saturn promoted their plastic body panels was to give the customer a baseball bat and tell him he could have a dollar if he put a dent in the car. I want more than a dollar. Tell them what, let me bring my own bat, and if I can dent it, I can have the car?.... My own bat is a "Custom made" 10lb brick bat. Some people may know it as a "Sledge" hammer, I just call it a brick bat... it bats bricks?... Custom made... I know someone who makes handles, he made on just that little longer for me, 'cos I am a little taller than some....
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Post by c64 on Aug 6, 2014 11:56:01 GMT
the way Saturn promoted their plastic body panels was to give the customer a baseball bat and tell him he could have a dollar if he put a dent in the car. I want more than a dollar. Tell them what, let me bring my own bat, and if I can dent it, I can have the car?.... My own bat is a "Custom made" 10lb brick bat. Some people may know it as a "Sledge" hammer, I just call it a brick bat... it bats bricks?... Custom made... I know someone who makes handles, he made on just that little longer for me, 'cos I am a little taller than some.... So, it's a real LART?
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Post by c64 on Aug 8, 2014 10:56:46 GMT
I don't know whether the Smart is painted or molded in color. Not sure if it is still valid: All Smart cars are painted black, the individual colours come from all the panels, the metal is always black. Looking at spare part databases, you either can't have any panels or the panels are always without any colour code so I assume they need to be spray painted individually. In my area there is a company which offers "printing" your Smart. They remove all plastic panels and run them through "a giant 'ink'jet printer". They accept all kinds of graphic data, even JPEG from your digital camera.
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Post by the light works on Aug 8, 2014 13:22:23 GMT
I don't know whether the Smart is painted or molded in color. Not sure if it is still valid: All Smart cars are painted black, the individual colours come from all the panels, the metal is always black. Looking at spare part databases, you either can't have any panels or the panels are always without any colour code so I assume they need to be spray painted individually. In my area there is a company which offers "printing" your Smart. They remove all plastic panels and run them through "a giant 'ink'jet printer". They accept all kinds of graphic data, even JPEG from your digital camera. I've said before, but - when they were originally talking about importing the Smart to the US, one of the selling points was that you could mail-order replacement body panels in your car's color, change them yourself, and mail the broken piece back for recycling, at their cost.
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Post by c64 on Aug 8, 2014 14:01:50 GMT
Not sure if it is still valid: All Smart cars are painted black, the individual colours come from all the panels, the metal is always black. Looking at spare part databases, you either can't have any panels or the panels are always without any colour code so I assume they need to be spray painted individually. In my area there is a company which offers "printing" your Smart. They remove all plastic panels and run them through "a giant 'ink'jet printer". They accept all kinds of graphic data, even JPEG from your digital camera. I've said before, but - when they were originally talking about importing the Smart to the US, one of the selling points was that you could mail-order replacement body panels in your car's color, change them yourself, and mail the broken piece back for recycling, at their cost. Of course you can order parts from the manufacturer ready to use. You give them the vehicle identification number and they know everything about the car including colour. But if you order from spare part dealers, all you need to give them is the model, built year and "vehicle key" (the one also used for the insurance to figure out manufacturer, model, body type and engine strength). There is no clue for the colour involved. I could order the panels from the manufacturer using the identification number of the vehicle or from a painter using the colour key from a sticker inside the car. Or just give the painter the vehicle and they scan the panel.
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Post by c64 on Sept 21, 2014 18:35:19 GMT
Today I have worked on my "new" car again.
Unlike my old one, this one was parked outside for over 19 years (The previous owner owned it for 19 years and has no garage, I had talked to her. I have no clue what the first owner did.
I have transferred a lot of the plastic panels from my old one to the "new" one. Even if the cars are almost identical and about the same age, all plastic parts of the "new" car are very brittle and start to peel. Also the plastic clips snap in half when trying to remove the panels. On my old car, most of the clips remained intact. Fortunately I once had bought a big bag of clips for my old car but never used them.
Using plastic for structural purposes is a bad idea, plastic ages, especially when in the sun. An "all plastic car" would have to have a "best before" entry in the documents and you need to throw the car away when it became too old.
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Post by the light works on Sept 24, 2014 15:40:46 GMT
Today I have worked on my "new" car again. Unlike my old one, this one was parked outside for over 19 years (The previous owner owned it for 19 years and has no garage, I had talked to her. I have no clue what the first owner did. I have transferred a lot of the plastic panels from my old one to the "new" one. Even if the cars are almost identical and about the same age, all plastic parts of the "new" car are very brittle and start to peel. Also the plastic clips snap in half when trying to remove the panels. On my old car, most of the clips remained intact. Fortunately I once had bought a big bag of clips for my old car but never used them. Using plastic for structural purposes is a bad idea, plastic ages, especially when in the sun. An "all plastic car" would have to have a "best before" entry in the documents and you need to throw the car away when it became too old. had an ex girlfriend who had bought a Honda prelude brand new. when the car was 10 years old, the metal door hinges had rusted to the point that the driver's side door fell off. plastic isn't the only thing that ages.
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