Introducing the Mercedes Production System

Hardly a week—let alone a month—goes by without a new model being presented by the DaimlerChrysler colossus; the frequency is such that sometimes they barely register a flicker on the interest scale. However, when it is a mainstream model bearing the three-pointed star then it is a different matter altogether.

When the C-Class' predecessor was launched by Mercedes 17 years ago, it was met with a slightly upraised eyebrow by the motoring media: the German company had staked out its territory in the mid- to large-size sedan category and introducing a smaller model seemed in danger of devaluing the brand. However, the buying public loved it and the 190 went on to become an important factor in the marquee's revitalisation at that time.

The launch of the C-Class as a replacement in 1993 did nothing to dampen Mercedes' success in the small sedan segment, with sales totalling 1.6 million over the seven-year period. However, the model never quite achieved the cachet of one of its arch-rivals, the BMW 3-series. Last year in the U.S., for example, BMW saw 3-series sales rocket 34%, from 57,520 units to 77,138, while Mercedes watched C-Class sales decline 13.6%, from 34,487 to 29,770 units. Borrowing much of its looks and technology from its S-Class big brother, the new C-Class has therefore arrived in the nick of time.

The new C-Class is being made in three plants: in Bremen and Sindelfingen in Germany, and in East London, South Africa, from where right-hand drive models will be sourced. All three factories have undergone extensive modifications over the last few months to accommodate the company's so-called Mercedes-Benz Production System (MPS) that it has been busily developing over the last few years and which will be applied throughout the DaimlerChrysler group within the next three years.

Since the start of full-scale production, the daily output of the Sindelfingen plant has been around 300 units, but this will be increased to 560 by the end of the year. At the same time, another 525 will be leaving Bremen every day. In total, 85,000 C-Class sedans are on line to be produced in the first production year in assembly halls No. 36 and 38 in Sindelfingen, while 65,000 more will be issued from Bremen, the 150,000 production target representing a 40% increase in first year production compared to the predecessor model. The adoption of MPS from the outset has improved efficiency so much, says Mercedes, that the 12 months it took to ramp up production of the original C-Class in 1993 have been halved on the new version.

A logical development of existing manufacturing methods, the basis of MPS is the adoption of working groups on the assembly line, increasing modularity, and the establishment of multi-skilled teams that have overseen the design, development and manufacturing processes from the beginning of the program. It was, for example, the inclusion of a number of specialists from the production plants in the development process that resulted in the optimisation of the vehicle from a manufacturing point of view. By being involved in the manufacture of pre-production vehicles at an early stage, they were also able to gain valuable experience when it came to assessing how the different phases of the production process could best be configured. These high standards were also constantly further developed after the start of the pre-production series, and process reliability was therefore continuously improved.

One of the new production system's key features is its modularity. More than any other Mercedes model, the new C-Class comprises a number of modules that having been built off-line and offered up to the vehicle on the assembly line. For example, the rear window is pre-assembled with all its aerials and electronics systems before it is installed onto the vehicle. The front endmodule—comprising the head lamps, bumpers, radiator, fan and other components—is supplied as a complete unit and fastened onto the front of the vehicle with 12 bolts. And the engine, gearbox and exhaust system are installed as a single pre-assembled unit fastened onto the car with 18 bolts under precisely controlled torque and turn angles. In addition, the metal panel work is open at the front end to facilitate all final assembly operations in this area.

All these modules benefited from having production engineers in the development team, as they were able to signal any possible manufacturing problems at an early stage. A case in point is the elimination of cross members in the engine compartment to allow the complete drive unit to be installed from underneath in one piece and in a single operation.

With maximum precision and minimal tolerances being key MPS features, the production engineers have developed what they call "soft touch form and piece." In the body shell, for example, the actual dimensions of the individual body panels are compared with the specified data and in the event of even the slightest deviation, the parts are reshaped for the ideal fit. In the eternal quest for "zero defects," an error-signalling system, newly developed for the C-Class, simplifies the fault-finding process so that the normal working process is back to reliable operation within a short time.

Another benefit of MPS, says Mercedes, is in logistics where the number of parts stored—at least by Mercedes standards—has been dramatically reduced. While part stocks of the assembly line of the outgoing model represented up to five hours of production, the material supply on the new model has been reduced to just two hours.

"The new Mercedes-Benz Production System represents a synthesis between assembly line automobile production based on small, precisely timed steps, and team-working in work places with very large time contents per employee," says Helmut Petri, member of the board of management for the Mercedes-Benz passenger car division, and head of production. "Group-based work will play an increasing role in the future, though we will not be abandoning assembly line work altogether, but we will be integrating employees even more intensively into the definition of each individual operation. In this way, we can combine the advantages of both methods, increase productivity and further improve our international competitiveness. At the same time, we are optimising the quality of our cars at the highest level."