SUV plastic under body tray
SUV plastic under body tray
(OP)
What material would you suggest for a SUV plastic under body tray (aero-cover under the engine).
It has to pass tough off road durability testing.
It has to pass tough off road durability testing.





RE: SUV plastic under body tray
http://www.geplastics.com
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RE: SUV plastic under body tray
Regards
pat
RE: SUV plastic under body tray
Modern bumper covers are not very damage tolerant. It seems that the design criteria are minimum cost (obvious) and thermal expansion just enough to tolerate paint baking. Maybe that is pessimistic - what do you think?
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RE: SUV plastic under body tray
Ken
RE: SUV plastic under body tray
One dissadvantage of PP in bumpers is that they need to be painted off line (as the PP will not withstand the temperatures in a normal paint oven), or at least had to when I was involved about 10 years ago, but this I expect would not need painting.
Another dissadvantage of any plastic, but especially PP is it's high co-efficent of expansion, especially when compared to steel. This means that bumpers must be designed to hide the extra expansion vs the steel body. As I guess this underbody cover will only go from chassis rail to chassis rail, and is mostly out of sight, I expect that this would not matter in this case.
I am presumeing that this is aero, not protective, as I would probably advise steel for a skid plate.
If it is a skid plate, and was to be plastic, I wouldn't consider anything other than super tough or glass filled nylon. Nylon would also be my second choice to PP for an aero only component, that is if the environment was to severe for PP.
If you carefully choose the right grade of PP/EPDM for your trials, you should be able to pick one with similar shrinkage to nylon 6, so the mould could work for either material, giveing the luxury of alternate materials to test in the field.
Obviously, this is all pretty well off the cuff nonsence without a lot more detail about the design, function and environment of use.
I would prefer to refer to Noryl GTX as PPO/PA alloy as this is suposed to be a technical forum, not a marketing tool.
As I expect that ultimate dimensional stability, and paintability are not an issue here, I see no advantage in PPO/PA alloy over PA.
Regards
pat
RE: SUV plastic under body tray
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RE: SUV plastic under body tray
CoryPad
I looked up your profile, and realised you were not a plastics salesman, but a quite well qualified materials engineer, with a focus more towards metals.
I also noticed that you are a very active participant, who seems to give more than he takes by the stats I saw, so my appologies if a slight was percieved.
I do have a bit of a comercial thing against GE, as over here, they take a very gung ho approach and polute any presentations at technical seminars with very heavy commercial bias, so any implied slight was at them, not you.
My appologies for any offence implied.
My last involvement in an auto bumper application was to try to get a boxed in nylon beam filled with PU foam specified as bumper combined structure and cover. Its main features were weight reduction, reduced assembly processes and online paintability, but it worked out to expensive compared to a pp cover over a spot welded steel reinforcing beam
Regards
pat
RE: SUV plastic under body tray
I know GE has patents on PPE (in fact, PPO is a trademark for their version of PPE) and PPE alloys.
Thanks for the "well qualified" compliment. I am qualified to design/engineer with polymers, but I do have a focus more towards metals. One "complaint" I have regarding Eng-Tips is that the polymer side has fewer "good" questions and fewer experts.
No slight was perceived. Similar comments have been made regarding GE Plastics by many people.
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RE: SUV plastic under body tray
There is an all aero-cover version and a skid plate version which still recieves a short aero-cover.
Both versions have to pass some serious off road durability testing, that results in some hard contact, although at present I'm not sure if the initial failure is the fasteners.
I have spoke with a GE rep who suggested most of the materials listed in the comments above. The problem being the delta cost per pound compared to the PP we are using now.
There does not seem to be an in between choice, from 45 cents a pound we are going to $1.60 > $2 a pound.
All the bumper covers (fascias) we produce are in TPO.
Thanks for your thoughts.
RE: SUV plastic under body tray
Nylon would certainly be my second choice, filled or unfilled, depending on the mode of failure.
If you already have a mould, try some extrusion grade 6.6 in the existing mould. With a really hot mould, it might shrink almost as much as PP co-polymer.
The extrusion grade will give increased toughness without looseing shrinkage, so the parts just might still fit.
What is the mode of failure of the existing PP parts
e-mail photos of new and failed parts or original drawings of parts to patprimmer@swiftdsl.com.au if you can. I will then have a much better idea of your problem.
Are the parts tearing off from the bolt holes, wearing out, or cracking and breaking.
Regards
pat
RE: SUV plastic under body tray
RE: SUV plastic under body tray
Almost without exception, I was called in to fix problems, after all else hadfailed, and the mould was made and shrinkage thereby locked in.
I will wait until I see damaged parts, prefferably at various stages of damage.
Regards
pat
RE: SUV plastic under body tray
RE: SUV plastic under body tray
assuming you dont need to paint it due to location.