BMW's Spartanburg, S.C. factory was completely converted into a state-of-the-art facility in less than three months. A total of seven key solutions in the final assembly operations -- from the joining of the chassis and the engine through different conveyor systems and the complete automation system for the plant -- was accomplished with assistance from Siemens.
Production of the 3 Series BMW began at the factory almost 13 years ago. Today, more than 150,000 of the BMW Roadster Z4 and the SUV model X5 are produced here annually by the facility's 4,500 employees. Recently, BMW decided to extend the production to include other models, without increasing the factory floor space. This project required extensive conversions, including the replacement and enhancement of nearly half the existing systems.
The two-line assembly system was converted into a one-line system. At the same time, it was enhanced with the latest manufacturing technologies. The X5 and the Z4 are now assembled here in all three models including the Roadster, Coup and M. Siemens acted as general contractor for a total of seven projects and acted as a sub-contractor in another three units of the facility.
According to Dieter Lauterwasser, BMW vice president of assembly, "The one-line system will give us the flexibility to vary model combinations from 100% X5's to 60% Z4's and 40% X5's."
One of the most interesting sub-projects was the marriage, which consists of 10 stations with one automatic assembly station and one automatic nut-running station enabling a previously unknown precision and eliminating the non-ergonomic overhead work that had to be performed in this production area.
Another important task was the modernization of several conveyor systems. For this work, a completely new skid system with 81 skids was installed. Another 300-meter long skid system was converted. Additionally, a 150-meter long chain conveyor system, as well as a heavy load conveyor with a total of 91 suspension tackles, was installed. Altogether, new conveyor systems with a total length of six kilometers were installed.
A special challenge in the Spartanburg project was that the whole conversion had to be organized with as little interference to the ongoing production as possible and be completed within a three-month timetable. The first partial shutdown of production was not made until nearly two-thirds of the project had been completed and lasted less than six weeks. The remaining production stopped just prior to completion of the project and continued for less than three weeks. Delivery stoppages were therefore limited to only a few days plantwide.
The use of the digital factory (pilot plant) during design for critical units such as the marriage helped reduce risks early on. All crucial mechanical and automation technology components were set up and rigorously tested in an 8,000 square meter test facility before installation. The fully functional systems were then transferred to the production facility in the few weeks available and integrated in the overall system.