quote:
Originally posted by bpossel
As I have taken apart my car for the upcoming repaint, I have wondered how the factory originally painted the items ¨.../...anyone have any insight on the original factory process?
A most interesting subject that you bring to the table, Bob. A definite matter to be included into this Group's technical database, covering the W113. Step by step we should gather information, to have an authorative guide for restorers.
As a basic documentation, I attach below the text from an article published in 1963 in the M-B factory magazine "In Aller Welt". W113 enthusiast Frank Mallory (RIP) put this into digital form.
For W113 group members who became interested in these matters recently (or are new members) I refer to Tom Colitt, yourself and others who posted on this Forum about a year ago.
http://sl113.org/forums/index.php?topic=6318NEW VEHICLE PAINTING PLANT IN SINDELFINGEN(from Mercedes-Benz in aller Welt #64, 7/1963)
As supplied by Frank MalloryDay in, day out, thousands of cars, gleaming with new paintwork and chrome-plated trim, are released from the assembly lines of automotive engineering plants.
Quite understandable, proud owners of a new Mercedes expect the brand-new appearance of their cars to last for years. Paintwork of vehicles is constantly exposed to the risk of corrosive attack, particularly by thawing salts, soot, sulfur dioxide-bearing fumes and the like. Corrosion can also be caused by mechanical damages, e.g., by impact of stones against the underbody of cars. Already for years, automotive and chemical industries have closely co-operated with a view to combating corrosion. Improvement of protection from corrosion was one of the chief requirements, on which planning of the new vehicle painting plant in Sindelfingen was based.
Since recently, the plant operates at full capacity; design and layout include all the advances made through the years and fully satisfy all demands of increased protection against corrosion. A visit to the new plant is rewarding indeed. The vast shed, flooded with daylight, is criss-crossed by conveyors on floor level, in mid-height and overhead arrangement, running, so it seems, aimlessly in all directions, carrying car bodies in a wide variety of color tones slowly dipping down and disappearing into a long, dark duct. Under the expert guidance of Mr. Hafemann, the engineer in charge, we very soon realize that the plant operates on a carefully planned working schedule.
The metal-finished bodies are transported by overhead conveyor to the painting plant through a tunnel of 2,300 ft. length. First, the steel sheet, which shows a bluish sheen, is pre-cleaned by hand. Thereafter, the bodies progress to the washing and phosphatizing station, which is about 300 ft. long. After thorough removal of any remaining dirt and grease, the metal surfaces are provided with zincphosphate coating, which safely prevents rust formation at places, where the paintwork is damaged, and at the same time forms an adhesive base for the initial paint coat.
Next, the prime coat is applied by dipping at two stations in parallel arrangement. The body dips slowly into a bath of 10 x 23 ft., which contains no fewer than 52 tons of paint. At the bottom of the bath, the body is tilted; the air trapped in the hollows escapes and forms vast bubbles on the bath surface. Then the body is lifted out of the bath and the surplus paint allowed to drip off. For each body, more than 26 lbs. of paint are used. The dip coating method ensures easy access of the paint to remote corners, hollow spaces, etc.
Following dip coating, the body is transported along the conveyorized line to the drying oven, where it is dried by dark infra-radiation and a subsequent steam-drying section for 20 minutes at a temperature of 284 deg. F. Cooling is followed by treatment of the underbody in the PVC booth. By subsequent baking, the solvent-free agent provides a tough yet elastic coating, which protects the underbody from corrosion.
After each station, workpieces are rigorously tested. No car body is released for the next phase unless its paintwork is perfectly finished and fully free from blemishes or other faults and defects. All Mercedes-Benz cars receive four paint coats. After drying of the prime coat, the finish coats are applied by spraying. Bodies receive their second coating by the electrostatic method: a rotating disk with a voltage of 100,000 V charges the finely dispersed paint particles, which are attracted by the nearest negative pole, i.e., the body, on which they settle.
After passing through the continuous baking oven and the subsequent cooling station comes a sanding step. Then the bodies progress down the return line to the pre-finishing booth where the paint is applied by hand spraying guns in the final color tone of the vehicle. Again, the body is passed through the drying oven and thence to the sanding station. By thorough cleaning, all metal surfaces are prepared for the final coat.
Next, the body is heat treated at a temperature of 266 deg. F so as to allow the synthetic resin constituents of the paint to solidify. Finally, the body is discharged from the baking oven with a gleaming, corrosion-resistant finish. Once again, all bodies are tested before they are released for final assembly. Prior to leaving the painting plant through the tunnel mentioned above, the luggage compartment and the beads are given a sprayed-on protective wax coating.
Vehicle painting requires a maze of complicated auxiliary equipment. Air consumption for suction removal of the paint mist is in the region of 53 million cft. per hour. Plant design ensures that clean, conditioned air is supplied to the spraying booths; after removal of the paint particles, the air is discharged to the outside. For air scrubbing, an hourly circulation rate of 176,000 cft. water (307 Imp. gals. per second) is required. Work of the washing, phosphatizing and sanding stations largely depends on the availability of water of a high degree of purity. In the ion exchanger, more than 3,000 cft. water per hour are softened and conditioned. By a centrally arranged feeding device, paint is circulated to the various points of consumption through an extensive piping system.
All operations are controlled from a central control station, which is arranged at the front wall and juts out into the shed. The large panels are a maze of mysterious, constantly changing luminous signals, the soft hum of the relays fills the control station. In the control station, heart of the plant, experienced engineers help to maintain and improve the workmanship in Mercedes-Benz vehicles and thus ensure that cars will retain their well-groomed appearance for years in all climatic zones of the world.
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/Hans in Sweden
