Production of the X1 crossover has started at BMW’s plant in Leipzig, Germany and that of the 3-Series saloon has halted. Although taking design cues from the X5 SUV, the smaller X1 features an all-new chassis that - in a first for any of the company’s ‘X’ models – offers either two- or four-wheel drive. “Production of the 3-Series ended in December,” says Michael Janssen, Communications Manager for the BMW plants in Leipzig, Berlin and Eisenach. “Towards the end of production, we were only building 100 3-Series per day. On the line now we have three different 1-Series models (threedoor hatch, coupe and convertible) and the X1.”

BMW has recently consolidated production of its other X-Series models at its plant in Spartanburg, South Carolina; X3 (formerly built by Magna Steyr in Graz, Austria), X5 and X6. With this in mind, why was Leipzig selected as production site for the X1?

“I think the main reason is that the X1 is focused more to the European market than the other X models. Also, with the other X models, Spartanburg is almost at full capacity.” How is capacity at Leipzig? “Currently we’re producing 720 vehicles per day, with more than 300 X1 units. This is close to our maximum,” says Janssen. “Standard capacity of the plant is 650, but this is in a standard two-shift pattern, so there is always the opportunity to produce more – or less. Production flexibility is a big issue here.” According to Janssen, the recent market downturn forced BMW to reduce production across all its plants. At Leipzig, output in early 2009 fell from close to 700 units per day to 380 on a single shift running six days per week. A dramatic change in production, but there were no layoffs.

“We maintained a constant level of employment using two instruments. First, we have working time accounts, ranging from –300 to +300 hours. An employee is paid a regular salary, but may work more or less. We rebalanced the accounts in 2009 when went back to a two-shift model. By the end of the year, the average was down from –120 to about –20 hours. The second is using agency workers. When we switched from a two to a one-shift pattern, the number of agency workers fell from 700 to between 50 and 100. We now have several hundred temporary workers at the plant.” Leipzig is now on a two-shift, six-day rotation, due to both the market success of the X1 and demand for the 1-Series convertible. Janssen is quick to point out that the plant is not simply preparing for an anticipated seasonal upswing in demand for the convertible. “We’re not producing stock which we hope to sell later. We’re producing cars based on customer orders. We simply get a lot more orders in the spring for the convertible than in the fall and winter.”

New press shop for Leipzig
There have been a range of large and small adaptations made to production processes across BMW’s Leipzig plant to accommodate the X1. The largest addition, in terms of investment, is represented by the new press plant. “In 2005 (when Leipzig started series production) we had no press shop,” says Michael Janssen. “We started the factory with the bodyshop, paint and assembly. All the pre-pressed panels were delivered by suppliers and other BMW shops, Dingolfing, for example.”

Manfred Erlacher, Plant Director at Leipzig, carries on the story: “Construction of the press shop started in 2007 and it was integrated into production last year (2009). It represents an investment of €100m. The facility was built to make large parts for the X1; today, we receive parts such as the roof, bonnet and door sides from our own press shop.” Supplied by Schuler, the installation features six individual presses on the single line. “It offers a total pressure of more than 10,000 tonnes,” he continues, “with the head press delivering 2,500 tonnes. The machinery, how the stamped parts are moved, is also very new.”

Erlacher is referring to the highly-flexible crossbar feeder technology. Based on a seven-axis movement, the system is very fast, both in terms of part movement and production of pressed parts. Taking advantage of the co-ordinated reach of the system’s internal part pickers, the stamped sheet metal is transferred in unison between individual presses, meaning there are no wasted press movements. “It would be quicker if it was making smaller parts, but for a large press it’s quite quick, completing 17 pressings per minute,” says Erlacher. “While the press line was designed to supply the X1, we’re now also producing parts for the 1-Series.”

The press uses pre-cut blanks delivered from suppliers including ArcelorMittal, Thyssen Krupp and Salzgitter. The press shop does include space for a coil hall, which at a later date could receive rolled steel for cutting blanks on site. Erlacher says that while there is no timeframe for this, it remains a future option. In terms of tooling, BMW’s own facilities at Eisenach, Dingolfing and Munich provide the necessary equipment. Despite weighing up to 40 tons each, die sets can be switched in a minimum of three minutes.

Adjusting production processes
While Leipzig is famous for its use of conveyor systems, most notably the open conveyor installation that takes car bodies through the facility’s administrative area as they advance to the paint shop, it was decided that a more basic option would be used to transport completed body panels to the weld shop. Janssen: “The first idea was to have a bridge with an automatic transport system, but due to the required investment and other issues, this was not realized. We simply move parts with forklifts. It’s a classic transportation solution.” In the bodyshop, allowances had to be made for the larger geometry of the X1. “We produce all car bodies on two central lines, two models each, but the sub-components are produced in specific areas. We had to build up one of these areas in body-in-white to produce sub-components for the X1.”

While chassis welding is completed automatically, the doors and front and rear closures are manually fitted in the weld finish area; one of the few production processes where the X1 and 1-Series separate into model-specific work spaces. Janssen says that in terms of blocking, there are no limits put on how many units of a given model can be welded in sequence.

In the paintshop, new routines were required to guide the robots around the larger X1 body. According to Manfred Erlacher, reprogramming robots, either in the paintshop or for welding, takes approximately two years. Initially, new tasks – and the required movements - are designed and programmed by BMW’s R&D team in Munich. A CAD tool then develops the source code needed to guide the robots through the final routine, a process which can be done by BMW or a third-party company. Finally, the new program is installed for testing. Minor changes and corrections can be carried out by BMW staff, who use a direct machine interface to make final adjustments.

In final assembly there have been two major changes to accommodate production of the X1. First, a new station has been added to install the ‘panorama’ sunroof. Supplied by Kuka, a robotic arm automatically picks a sunroof assembly from the lineside racking and then applies it to the vehicle. Much like front and rear glass, the process is completed without human intervention. While Janssen does not reveal the value of the new investment, it’s clearly a substantial amount, as the cell also features a full vision system. According to Erlacher, the primary concern with adding a new model is how the line workers deal with the new parts and the required motions. “You need to know where to put the screws, where to fix something. But it’s not an issue of weeks, perhaps only one or two shifts to learn the new parts.” Erlacher, on job sharing: “There are teams of between 15 and 20 people responsible for five, eight or ten stations. In that part of the line, they may switch. Within the teams they are responsible for deciding which jobs the individual team members will complete. The team leader remains responsible for job allocation, quality and output.”

The other change in the assembly hall is an extension to the Moll-supplied conveyor that carries car bodies through trim and final assembly. The additional length, made necessary due to the addition of the sunroof cell, is housed in a new structure which BMW refers to as a ‘finger’. These elements offer a range of benefits in the assembly hall. “Trucks unload parts directly to the finger where those items are required,” says Janssen. “It’s a great advantage to bring inventory lineside, it’s just 10m from the truck to the line; the trucks hold most of the inventory. We don’t have any material transportation with forklifts inside the assembly hall. The other advantage is that if we need to change line length, we can add or take away elements in the fingers.” The fingers also serve to reduce the physical length of the assembly hall. “There are now five fingers, located to the east of the main line; all cars go through all fingers. If you stretched the line out, it would be about 2.5km long.” Opposite to the main assembly line, finished vehicles are conveyored through filling stations and on to final checks. Janssen says that this was done in order to have the completed vehicles arrive at a central point within the facility. “It allows easy access for responsible parties to come and discuss any build issues.”

Setting up the supply chain
Like many new plants, Leipzig has its own supplier park, or ‘supply centre’. According to Manfred Erlacher, the plant was designed to accommodate five or six key part producers located close to the factory. “We discussed several alternatives, including a remote location 20 or 50km away, but we decided to have them onsite and in our own buildings. The buildings used are owned by BMW and the suppliers rent their space. If we decide to change a supplier for any future models, they just move out and the next one comes in. They don’t have the risk of a high-value investment.”

Key suppliers in the supply centre deliver the large, customer-specific modules, such as instrument panels, seats, ceiling modules, front-end modules and pre-mounted axles – of particular importance with the X1 being offered with two- or four-wheel drive. Erlacher says that owing to customer considerations, order sequencing information is available only 150 minutes before parts must be delivered to the line. “They really do produce just-in-time and just-insequence!” Parts are delivered using an automatic conveyor system.

Although they are described as ‘customer-specific’, there are no ‘standard’ modules. “They are all customer-specific!” says Janssen. “There are two major challenges in the BMW production system. One is the huge number of possible vehicle variants. It has been calculated that a BMW can be ordered in 1017 possible model variations. No two cars are the same, they are specific to a customer order. Parts maybe produced in thousands of different variations, combinations of electric or manual movement, equipment, fabric, etc.” He goes on to point out that such is the option-driven variation between individual cars, there are stations on the assembly line where cars receive no equipment and only move along based on the current 86 second takt time. The other challenge is that customers may change their order up to six working days before the vehicle is due to enter production. Janssen: “We have a rough idea what we will have to produce, but we don’t know exactly what that will be even for next week.”

Final order sequence is fixed only four days before the start of production. This means that all the JIT and JIS suppliers around the world, in Europe and elsewhere, only get the information about what has to be delivered four days before it has to arrive in Leipzig. Janssen forwards the example of the company producing wiring harnesses in Romania. “They have to produce the product, based on vehicle specifications, which is a manual operation, go through quality checks and deliver by truck to the plant. Delivery alone is two days, so it’s a tough job for the suppliers.”

According to Janssen, while production and assembly at Leipzig is state-of-the-art, the supply chain and related logistics activities are an on-going challenge. Though while the plant was designed to facilitate flexibility and sustainability, it also addresses logistics problems. “It’s the idea behind the fingers, the total structure.”

As can be expected, part delivery is a main reason for choosing Leipzig for the plant site. “It’s located in the heart of Europe, with good transport links. There’s a major north-south, east-west motorway crossing here, a good rail connection,” says Janssen. He adds that in addition to the central location, it’s still not far from BMW’s Bavarian production sites. “We share know-how and people. We get parts from there and we also deliver parts. We produce some side frames for production of the 1-Series in Regensburg. It’s also important to be located within the existing supplier network, in Germany and Europe. Locating the plant in Portugal or Turkey would not offer the same advantages.” Asked if the same companies have carried over part supply from the 1-Series to the X1, Janssen says that nothing is taken for granted and existing suppliers have to bid for contracts in the same way as any potential suppliers. “When a new product is put into production, the suppliers are selected based on that project. On the X1, there were supplier decisions made not linked to the 1-Series. It could be the same, it may be different, but there’s no rule that says it must be the same supplier – with the exception of suppliers in the supply centre. There could be a decision to use a different seat supplier, but then we would have two different seat manufacturers on site, which – in terms of economics – would defeat the whole purpose. Faurecia is producing seats for both models, but that wasn’t a guaranteed decision. It’s always the best business case.” Which in a lot of cases comes down to cost – and quality? “Cost is quality!”

Model development
According to Michael Janssen, from sign-off to production, the development of the X1 required about 30 months. From the outset, he says, it was clear that the model would be built in Leipzig, but development could have been faster if the building of the first prototypes had been completed in Leipzig.

“A plant should be involved as early as possible. Of course, in the development phase, you must create the new car, its design, functionality and usability, all the customer aspects. But you also have to make sure that it can be produced efficiently and economically. So you need the production aspect to be involved at a very early stage of vehicle development.

“It’s very good to know which plant will be producing the new model. Then, the plant experts from that plant can work with the development department in Munich, and the prototypes are built here, in the same factory where they will be produced. The first prototypes are produced between 12 and 18 months before the start of production. We need a year in the factory to integrate the new model.” With a brand new model, do any restrictions on plant set up influence the design of the new car?

“The X1 was designed for the customer, the market. The plant has to be flexible. Our designers don’t say it should be 4,000mm long, but the factory can only accommodate 3,900mm and let the market learn to accept it. Our plant and production experts are concerned with making the finished model fit out production processes. The design is done to meet customer expectations.”

As such, Janssen anticipates that the Leipzig plant will not see any immediate investment beyond that required to build the X1. “It’s a new factory, still one of the most efficient and flexible in the world,” he says. “If BMW was to build a new factory on a greenfield site, I think that it would be roughly the same as this.

Topics