Building the 335d: A Tour of BMW’s Munich Factory
BMW Werk München (Munich Plant) is the company’s main factory, with 10,000 workers producing ca. 800 3er Series autos and 1,200 engines each day. The plant is located in the middle of Munich, adjacent to BMW’s Vierzylinder corporate headquarters building and the BMW Welt delivery and experience center. Each car is built to customer specifications and, given the multitude of options, colors, and engines available, the Munich factory typically builds only two of the very same car each year.
My 335d’s production started on 2 December with a coil of steel that was unraveled
and cut into plates that were then pressed into the right shape. The Press Shop handles 600 metric tons of steel plates each and every day and the steel is specifically selected for individual parts in order to meet BMW’s high standards.
Depending on the part, four to six production steps are required.
The parts formed for the 335d were then assembled in the Body Shop starting on 8 December until the car body was completed later that day.
Large panels simultaneously converge into a central spot for spot and laser welding as well as other joining techniques such as gluing. Robots seem to magically create the chassis by turning and rotating different parts. The robots in the Mobi-Cell perform spot welding with exacting precision.
The remarkable “Mobi Cell” Body Shell Concept is a BMW manufacturing innovation. Mobi Cell stands for “Mobile Standard Fertigungszelle” (mobile standard production booth). It makes it possible it to shift production stations within the body shop quickly and economically. The individual station can be combined with and connected to larger and more complex manufacturing stations, thereby improving the factory’s flexibility and ability to cope with changes in demand.
The next step in production is the Paint Shop. The 335d’s chassis was cleaned, dipped into a phosphate solution that serves as a foundation for additional layers of paint, and then four layers of color were applied in separate passes. First the primer was applied in the cathodic rotation dip, then filler, base, and clear coat were applied by robots and painting machines.
The cleaning stage was very thorough, using a blow cleaner with high speed airflow and rotating ostrich feathers. The 335d’s finish could easily have been ruined by the tiniest piece of dust so BMW uses ostrich feathers, which are very efficient at gathering dust, before sending the car to the primer booth. Click here to continue to page 2.
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