St. Louis Plant Assy Time Study

[Michael H.]

Re: Worst Drawing on the Internet

Sure glad I'm not involved in the paint business today. Now I understand why one paint source after another goes out of business. Maybe they should "just dip" all the bodies the same way that parts are dipped in 1050104.

I have a question that I'm hoping you can help with. Yesterday, Wayne Womble mentioned that he remembered painters in the booth at St. Louis changing just the material supply line to the gun for different colors and I was pretty sure that there was one gun for each color. I've been looking through my pic's to see if there was at least one shot of guns hanging on the wall but i each pic, there's something in the way. i can see all the air/fluid lines but not the guns. Most of my pic's are either from the 60's or late 70's but Wayne said he saw this in about 1976. Thanks John,

Michael

[Wayne W.]

Re: Worst Drawing on the Internet

I dont think that he was having any trouble with the gun. He finished painting and I plainly saw him plug the thing into another outlet and spray through the floor grate, then shoot the black under the front and rear fenders.

[Michael H.]

Re: Worst Drawing on the Internet

Ok, I misunderstood your previous post. I thought you were saying he changed guns when the next body rolled into the booth, for a different body color.

I would have to guess that if he was painting wheel wells in the final 2nd/3rd coat color booth, it was a temporary condition. The complete wheel well and underhood blackout was done at a station just past the final color booth, just before the reflow oven. It's not uncommon for problems on the line to temporarily move some operations forward or back one station while some equipment was being repaired.

[Wayne W.]

Re: Worst Drawing on the Internet

Could have been, but it was a just a quick back and forth swipe under the fenders. It didnt require any mask or anything. It might have been easier done there.

[Mike McKown]

Re: Worst Drawing on the Internet

Mike:

I never worked in the Corvette plant but the plant I did work in, the painters used one gun for all colors. They just changed paint supply hoses and then cleared the gun as Wayne described. Seems like I remember they blew some thinner through the gun to clear it of the previous color.

On the subject of wrong painted bodies. Yes, it did happen and it was not all that infrequent occurrence. In most cases, the body was not repainted to the scheduled color for at least three reasons. If for example you had a body painted red and it should have been yellow, you wouldn't want to re-paint it because if it hit the street and a customer chipped his paint and saw yellow under the red, you could well........... all sorts of bad implications. It costs a lot of money to paint or repaint a vehicle even in a facility geared for mass production. Last I heard, our cost was I think about $1400 per unit (it may have been double that) plus another re-run through the paint oven could slow production of the whole paint shop. What ususally happened was that the metal ID tag would be removed from a body still in the prime system that matched the wrong painted body and the tags were just simply switched. This also meant that the original serial numbers that were assigned to these two bodies were also switched but that was of no consequence at this stage of assembly.

It would not suprise me at all if the same thing didn't happen (and still happens) in the Corvette assembly process.

[John H.]

Re: Worst Drawing on the Internet

We used to calculate that it cost about $1.80 per car in regular high-volume assembly plants for a color change between units (for the cheap purge thinner sprayed through the floor grate to purge all the guns before spraying the new color on the next unit); this gave rise to the effort to "batch-paint" whenever possible. If you could get ten units in a row out of the Body Shop in the same color, it saved $18.00, etc.

Everything that went through the floor grate (color overspray and purge thinner) went into a sump in each downdraft booth in the old days and was disposed of as industrial waste. Later we figured out how to treat that waste chemically, recover the volatile portion, and re-use it as purge thinner; the remaining non-volatile solids were then landfilled.

Then we added incredibly-expensive high-temperature incinerators for all the oven stacks to burn off the solvent VOC's (Volatile Organic Compounds) driven off in the prime and color ovens, and that led eventually to waterborne immersion primers and sprayed basecoat, which had (almost) no VOC's.

Clearcoats are still an issue - they're two-component, still have some VOC's, and contain isocyanates, so there are no people in clearcoat spray booths - only robots. Both non-isocyanate and powder clearcoats are in development, but nothing from that effort is yet commercially viable. High-volume painting is a VERY capital-intensive business, and even when you buy MILLIONS of gallons as the OEM's do, it still averages over $300 a gallon.

[Mike McKown]

Re: Worst Drawing on the Internet

Even though I stayed as far away from the Paint systems as I could, It sounds like your people and my people played golf on the same course at the same time and used the same caddy.

[John H.]

Re: Worst Drawing on the Internet

I guess I didn't fit the mold for a Detroit "golf course" auto industry executive; played golf once a year whether I wanted to or not, at the annual plant golf outing - Plant Manager had to be there. Fortunately, they were always the best-ball foursome format, so my kludge game wasn't too obvious, and my staff was kindly enough to contain their laughter