Porsche Leipzig attains a production depth of 90 per cent in body manufacturing. Over 100 production cycles, 386 individual parts are joined to produce the lightweight 500 kg body – by resistance welding (around 6,000 welds), 330 bolt joints, high-strength adhesives, rivets and laser brazing. 387 robots are used here. The body grows from bottom to top in four large steps.

Underbody, superstructure, add-on parts, finishing. First, the underbody – the platform – is built. For logistical reasons, it is subdivided into two sections: “Underbody 1” and “Underbody 2”. This is followed by the superstructure. This is the area of the body manufacturing process in which the side components and roof are added to the underbody. The superstructure is subdivided into three large areas. In “Superstructure 1” the inner side walls are welded to the underbody structure – these are the plates on the interior. In the next area, “Superstructure 2”, the outer side walls are mounted – these are the sheets of the exterior, which make up the design of the Macan. In “Superstructure 3”, the body is completed by mounting the roof. Following “Underbody” and “Superstructure” is the “Add-on parts line”, which is the third section in body manufacturing. Here, the doors, boot lid, front wings and distinctive bonnet – which were manufactured in parallel steps beforehand – are integrated into the body. Robots mount the doors and bonnet fully automatically, because the tight gap dimensions and transitions between surfaces require automated work methods. The boot lid and the wings are placed semi-automatically by workers. The fourth and final area is finishing, in which the body manufacturers check surfaces and perfect them if necessary as well as fine tune the add-on parts. Then the vehicles leave the body shop and are transported to the paint shop. It is especially exciting to take a close look at the production startup of the Macan in the body shop: the very elaborately manufactured aluminium bonnet, quality assurance and the Competence Centre, the manufacturing precision exemplified by gap dimensions and the actual birthplace of the car.

From five to 300 bodies daily. “The continual ramp-up of the production curve is always a special challenge,” says Siegfried Bülow, Plant Manager in Leipzig. The production expert has been working in this business field for decades now and knows all about starting up new models: “By the end of October 2013, five Macan cars were manufactured daily in pilot production; by the beginning of February 2014, the figure had grown to 100 cars daily. Ten weeks later, we will already be producing 300 Macan bodies per day.” And that is not even the theoretical maximum for daily production. Norbert Wagner, Body Shop Manager, explains that the Porsche Leipzig body shop was built “following a construction sequence from north to south.” At the north end of the hall, the front wheel housings are the first parts to be assembled, while at the south end, body manufacturing ends with assembly of the add-on parts. Manufacturing of the aluminium bonnet of the Macan is a masterpiece of production engineering. Wagner: “To produce such a design element, a part of such size and precision is without precedent.” The pressed parts of the bonnet come from Bratislava. An outer part, an inner part and the reinforcements between them. The body shop manager: “The individual parts are folded or riveted, and a high-strength adhesive is also applied between the outer and inner sheets. First, the outer skin is placed in the production equipment in which the bonnet will be joined. Then the inner skin is fixed in place. In the next step, a robot with six roller-folding heads goes to work and makes the folds. As an added benefit, the bonnet gets additional torsional rigidity from the adhesive. Then the bonnet is placed in a specially built oven on a special fixture that assures precisely defined dimensional tolerances of the part, even when subjected to heat. This oven cures the adhesive. Then the surface of the bonnet is treated, and it is assembled. The complex production process rewards us and especially our customers with absolutely perfect precision fit of the bonnet.”

Quality over quantity. Norbert Wagner once again: “Quality is our number 1 priority. Because with perfectly executed joining processes, we ensure that body properties and safety of the car are top level. That has to be checked regularly.” The head of the body shop explains specifically how that is accomplished: “On a regular basis, we tear apart the folded seam joint to see whether both parts were properly wetted with adhesive. We also place high value on weld checking by ultrasonic methods; we do that daily. We have employees who are specifically responsible for this. Porsche Leipzig also has a laboratory in the body shop. There, we study whether the welds hold even under extreme conditions.” Fortunately, defects are the exception today thanks to highly advanced technology. Production expert Wagner: “The introduction of adaptive welding control has meant tremendous progress in body manufacturing in recent years. This is a very innovative control method that can detect, during the welding process, whether or not the weld will be acceptable; welding control then automatically adjusts weld parameters. This method is very complex, but it is also very reliable.” Another dominant theme in quality assurance is what are known as functional dimensions. Wagner: “The car must be correct in terms of its geometry. That is why there are over 400 functional dimensions, and we make great efforts to ensure that they are right. We also have a dedicated crew assigned to this task.”

Competence Centres solve problems. Porsche is successfully striving continually to improve its processes and solve problems extremely quickly. In this context, “Competence Centres” have been integrated at the Leipzig plant in the body shop, paint shop and assembly. Norbert Wagner: “We have these Competence Centres in all four areas of body manufacturing: in the underbody, superstructure, add-on parts line and finishing. These are offices located directly in the production areas. All specialties that are responsible for the specific area are represented in these Competence Centres. Residing in the “Underbody“ centre, for example, are the shift leader, planner, quality control specialist and a geometry specialist who is responsible for conformance to dimensional tolerances. An example: if the centre receives a report from assembly that there is a problem, the quality representative routes this report directly to the affected Competence Centre in the body shop. The four specialists have the competence to solve this problem quickly. It is truly a unique arrangement to have these people working together in one Competence Centre.”

The birthplace of the Macan. The 100 cycles in the body shop begin, as mentioned, with the welding of the front wheel housings together with their suspension strut mounts and chassis legs. Nearly simultaneously, the front and rear floors are built in a nearby section of the system. All of these elements come together – transported by pallet conveyors – to station 1810 and are joined to become the underbody. As in all of body manufacturing, this is done with what are known as decoupling buffers. Wagner: “If there is a problem on the main line, if a robot fails for example, it is still possible to continue work at subsequent manufacturing stations thanks to the decoupling modules. Generally, we have between 10 and 20 parts in a decoupling station.” In fact, every worker in the body shop in Leipzig is familiar with station 1810. Thomas Riediger, Head of Planning at Porsche Leipzig GmbH: “This is really the birthplace of the Macan, because the underbody structure is created here. The car also gets its birth certificate at station 1810 – a transponder, a mobile data memory that serves as the fingerprint of the Macan, which contains the specific vehicle’s identification code. This transponder contains all of the details of the future Macan.”

An important geometry station. Cycle 1810 is also known as the “Geometry station of underbody 1”. That is because with the assembly of the underbody, the foundation has been laid in production for the extremely precise body geometry of the Macan. The reason is that the key elementary welds are made at this station in body manufacturing. Specifically, the underbody structure is clamped in place so that – in the jargon of the production people – the “geo welds” can be made. All of these tasks are a job for the robots. Incidentally, from this point forward, the structure is referred to as a “vehicle”; previously they were just parts. The underbody structure is now so sturdy that it can be conveyed as a whole to the next stations.

On conveyor skids to the paint shop. From station 1810, a robot with a handling gripper takes the carcass and places it on a transport platform – also known as a skid. From now on, the vehicle is conveyed through body manufacturing on the skid. Other parts are fed in from the side – which visually looks like a fishbone pattern. And it is built up in sequence in “Underbody 2”, “Superstructure 1, 2 and 3” and the “Add-on part line” and “Finish”. The next step is the paint shop.