i just painted my auto body panels with Dupli Color paint for cars and trucks i sanded the crap out of the panels before painting and after a couple coats i sanded again with 1500 grit wet&dry paper put a couple more coats on and let dry for a couple days before and after.
My daughter had a 1997 Saturn SL1. It was a basic car and the styling was not that exciting; however, it was reliable, peppy, got good mileage, and did reasonably well in the snow.
When her car got nailed in a parking lot the internal door repairs and cost of the skin was much higher than a comparable repair in most steel skinned economy cars. She did have it repaired and sold it years later with over 130,000 miles on it.
I think they were basically good cars, but the concept was not as cheap to produce; so, they probably operated with smaller business margins than alternate material choices.
Because of Plastic's high CLTE, "they grew and shrank when the temperature changed, requiring the cars to have wide, unappealing gaps around the doors, hood and trunk for clearance."
Looks like we need to go back to the drawing board and re-address the "gap" in our designs.
If gaps are a problem, figure out a way to either eliminate them through material selection or rethinking the mechanical design. You could also "hide" them or turn them into a feature so they work into the design.
I guess my opinion is simple: if you've got a problem, figure out a way to fix it (cost effectively)...don't give up.
(yeah, yeah, I know about wasting time and money on something that is difficult to solve can ruin your ROI, but somebody has to be idealistic!)
In college, I had a professor who spent a lot of time in his processing days producing (or attempting to produce) car panels for the Pontiac Fiero. The major problems that they had were material flow issues and eliminating flow lines in the panels. I am sure that by now these issues should be resolved. At least we hope son.
You mentioned UV, but environmental stress cracking phenomenas can also occur because of introducing additional materials, you did not consider during the design process of the product. For example customers adding a adhesive sticker containing a bad adhesive or solvent on top of your surface, can nicely lead to induce micro cracking. Cleaning agents are also always a very hot topic regarding environmental stress cracking.
PC/ABS is also notoriously susceptible to environmental stress cracking. It has a lot of good points, too, such as high impact strength, but the chemical incompatibilities are an Achilles heel. I am very hesitant to recommend it.
I might pick up a copy of Bob Lutz's book. He has a reputation for being a straight talker.
In its commercials, Saturn made a big deal out of its plastic body panels. Back in 1990, consumers who recognized the Saturn name associated it first with the plastic panels. So all of us wondered why the rest of the industry didn't adopt plastic. Now, thanks to Lutz's book, we know why. The irony is that many of us who have owned Saturns (I still own a Saturn Ion) like the plastic panels. They may be finicky, as Lutz says, but most Saturns were purchased for their low price and reliability, not for fit and finish.
Fifty-six-year-old Pasquale Russo has been doing metalwork for more than 30 years in a tiny southern Italy village. Many craftsmen like him brought with them fabrication skills when they came from the Old World to America.
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