Ever since the Macan began production in 2014, Porsche Leipzig has been a fully-fledged production facility with an ultra-modern paint shop and a dedicated body shop. Among other things, a second body shop and new logistics area were created for the complete production of the new Panamera.
The pioneering Porsche production system guarantees that a new vehicle can be optimally produced with top quality and a wide scope for individualisation in terms of features. A professional logistics system is crucial to be able to guarantee high-performing production with this complexity. Porsche works on the principle of the just-in-sequence method. A supply system controls delivery of the pre-assembled and model-specific components to the exact sequence of production and assembly time – in some cases directly to the exact location on the assembly line. In this way, Porsche benefits from the proven concept of a small stockholding. The distinctive features of production at the Saxony location are: transparent processes, the consistent implementation of the principles of lean production, which is always being improved through constant reduction and elimination of waste, as well as a continuous improvement process and emphasis on the highest quality.
Logistics: Setting the pace of production
Capable and highly efficient logistics are a crucial key to success at Porsche Leipzig. It sets the pace for production. Logistics face the major challenge of mapping the high variance in vehicle equipment and providing precisely the right material for the right vehicle at the right time. Each workday, 17,000 pallets for assembly and 8,600 for the body shop are delivered to the Leipzig factory in about 550 heavy goods vehicles. The material from these pallets is picked, sequenced or sorted in the correct order for production in the body shop and assembly logistic supply centres. The large variety and individualisation of parts makes accurate delivery of precisely the right parts necessary, which is ensured by vehicle-specific picking. About 270,000 ‘picks’, i.e. individual parts, are needed every day, which are processed either automatically or by staff and brought to the assembly site. One focus of assembly supply is the just-in-sequence delivery of about 75 modules, such as cockpits. These are delivered directly from the suppliers to the factory without interim storage, straight to the assembly location in exactly the correct order and at the right time. Logistics is also responsible for shipping the finished vehicles. 70 per cent of all vehicles from the Leipzig factory are transported by environmentally friendly rail.
Body shop: More than 90 per cent vertical integration
The body of the Panamera is based on the flexible modular standard kit (MSB) manufactured within the Volkswagen Group. Specific configurations in addition to various wheelbases are possible. This means that all models can be placed into the mix at the same production facilities without any restrictions. The new MSB body shop, which was built for the Panamera, has a production area of about 56,000 sq. m. This corresponds to an area of eight football pitches. The combination modules (ZSB) are precisely transported using electric monorail systems (EHB) to the installation location of the corresponding assembly line. A factory control system (body tracking) oversees that the right ZSB is in the right place at the right time. Right from the very first component, it assigns the ZSB to a vehicle order and constantly checks whether all the necessary components for the job are available. All fabricated assemblies and bodies are marked by a modern QR code and RFID, i.e. identification via electromagnetic waves and tested several times during the production run. This allows complete identification, control and visualisation of all production parameters in the body shop. 475 robots and 189 employees are needed for the construction of the bodies with a vertical integration of over 90 per cent. The body is made up of 430 individual parts and created by thermal and mechanical joining methods, and more than 200 m of adhesive. On average, 13 bodies are produced per hour in the MSB body shop.
Exterior skin of the Panamera: Made completely of cast aluminium
A special feature is the innovative lightweight matrix. Its aim is to target the use of the material with the best properties. The result is sophisticated manufacturing and welding technology of aluminium sheets, aluminium alloy and high-strength steel sheets. The entire exterior skin of the new Panamera consists exclusively of aluminium. This requires a very high level of expertise in tooling and in surface treatment for body construction.
The vehicle body always grows from the bottom up. It does this in four major sections: underbody, superstructure, add-on parts and finishing. First, the underbody – the platform – is built. Due to technical reasons, this is divided into three parts: front body, floor and rear body, which together form the underbody line. Assembly follows after that. This is the area in the development process of the body in which the side panels and the roof are added to the underbody. The construction process is divided into three major areas. In ‘superstructure 1’, the inner side walls are welded to the underbody structure – these are the plates on the interior. In the next section, ‘superstructure 2’, the outer side walls are mounted – these are the sheets of the exterior, which make up the design of the Panamera. In ‘superstructure 3’, the body is completed by mounting the roof. The third major section is the ‘add-on parts line’. Here, the doors, boot lid, front wings and bonnet – which were manufactured in parallel steps beforehand – are integrated into the body. Robots mount the doors and bonnet fully automatically as the tight gap dimensions and transitions between surfaces require automated work methods. Employees use a semi-automated process to assemble all the other add-on parts. 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.
Paint shop: Six stages to a perfectly painted body
The bodies of the Macan and the new Panamera will receive one of eleven current standard paint colours in the paint shop, an area covering 60,000 sq. m. Around 200 custom colours are available for specific customer requirements. The paint shop in Leipzig is one of the most energy efficient in the world. About 80 per cent of the heat needed is provided by the waste heat of an externally operated biomass power plant. It takes around 15 hours for the body to go through all six phases of the paint shop. It travels along a 6,548 m conveyor belt, the dryer length alone is 560 m.
Stage 1 – Pretreatment for cathodic dip coating (CDC): During pretreatment, the body is cleaned in a 60°C dip tank and degreased. Grease from the pressing plant, metal dust and other contaminants from the body shop are removed. This is followed by a phosphating process, in which a zinc phosphate coating is applied in a dip tank. It ensures optimal adhesion for the corrosion protection coating that follows later. The body is dipped into the tank and rotated 360 degrees, so that all cavities are reached.
Stage 2 – Cathodic dip coating (CDC): The cathodic dip coating dipping process gives the body high-quality corrosion protection. Once in the dip tank, the body is rotated around its own axis to ensure that all surfaces – even in cavities – are covered. The dipping process is referred to as cathodic, because the solids in the paint are deposited on the body surface by electrophoresis. This entails a voltage differential of 380 V being applied between the dip tank and the body. The resulting voltage distribution in the body yields a highly uniform coating.
Stage 3 – CDC drying unit: Afterwards, the cathodic dip coating of the body is allowed to drip, and then it is dried in a number of drying stages. Here, the body is sent into the first of a total of four dryers during the painting process. The first, the CDC dryer, reaches up to 185°C at its peak.
Stage 4 – Sealing of seams: Special PVC materials are used to seal the seams and flanges, so that no water can get in later on. The sealing process is performed fully automatically by robots. Underbody protection is also applied. It consists of a material containing PVC and protects the body against stone impacts. In addition, the seams at the doors, bonnet and boot lid are sealed. Very strict quality standards apply to the visible seams.
Stage 5 – Primer, topcoat, clear coat: Now, the actual paint layers are applied at a precisely defined air humidity and temperature. All paint stages – primer, base coat and clear coat – are applied by painting robots with electrostatic paint charging both internally and externally on the body. The primer coat, which provides stone impact protection, is available in three colours (white, anthracite and mid-grey). It is already colour coordinated with the topcoat that follows. The elastic primer as a substrate protects the topcoat from damage and simultaneously improves its structure. Before the topcoat is applied, the body is sent through a dryer at 160°C. Now the body is given the topcoat or base coat – and, with this, the colour selected by the buyer. At the end of the application, the topcoat undergoes intermediate drying at 80°C, before the topcoat is sealed with a clear coat, known as the topcoat finish. Fully painted, the body now passes through the third main drying unit. Here, the paint is cured at a temperature of 140°C. for around 45 minutes.
Level 6 – Light tunnel: In the final phase, the paint jobs on the bodies are monitored on the finishing line, and any painting defects are eliminated. A special light tunnel is used for this. It is equipped with extremely economical LED modules. Their light is projected as required onto the bodies using adjustable mirrors. This generates a very uniform strip of light that lets employees detect even very minor imperfections on the paint surface. In contrast to tunnel systems using fluorescent tubes, the new Ergo-Lux tunnel at Porsche Leipzig is not only better at detecting defects, but it also makes considerable energy savings thanks to its LEDs. This better economy is associated with less energy being converted to heat. In turn, this noticeably improves the climatic working conditions of employees in the light tunnel. After the final pass through cavity protection (HRK), the untreated body has become a high-gloss and cavity-sealed car body.
Assembly: Around 5,000 parts are built into the Panamera, Macan and Cayenne
With the launch of the Panamera, this assembly line – including the Macan and Cayenne – consists of a total of 235 individual cycles. The cycle time – the amount of time a Panamera remains at a single production station, e.g. a station where the front seats or roof rails are installed – is about two minutes. A total of around 5,000 parts are assembled. The bodies in assembly are transported on a plate line (with lift tables) or on pivoting hangers. The assembly area is subdivided into different lines. The Macan and Panamera move together here. Not until the ‘marriage’ of the body and power train/chassis does the Cayenne merge with the line by electric rail conveyor. First, there is the door line, followed by interior lines 1 and 2, the underbody line, exterior lines 1 and 2, the mixed line, chassis build-up and power train build-up (engine and transmission) as well as the famous marriage (chassis/power train merge with the body). After that, the assembly of the vehicles is completed at the thrust plate line and the final assembly line. Final assembly takes place in what is called the test field. Here, the vehicle computers are loaded with the current software, bringing the assistance systems to life, the chassis is fine-tuned, the headlight settings are checked, the engine is started for the first time, the body is examined for leaks and – after a drive on the test track – the vehicle leaves for final inspection.
Assembly in detail:
Door line: The doors are removed from the body at the beginning of interior line 1 and transported to the door line. Then they are fitted with the electrical system and the window motors, the windows, and the door trim, including speakers. Afterwards, the finished doors are transported to the new assembly line tray, where they are reconnected to their body.
Interior lines 1 and 2: Here, the vehicles are fitted with all their interior parts, including one of the most important components of all: the wire harness. The cockpit is also integrated, one of the largest complete modules in the vehicle. The cockpit is assembled externally, and – if the vehicle is ordered with this option – its upper area is upholstered in the finest leather. Here, industrial manufacturing melds with handcrafting. This is not a spectacular production step, but it is important on its path towards becoming a complete car: the ignition key is inserted into the Porsche for the first time. At the end, the car is moved to a different mode of conveyance. It leaves the lift table and is now suspended by a pivoting hanger so that underbody tasks can be performed more ergonomically.
Underbody line: Underbody lines 1 and 2 run in parallel to the door line in assembly. Components installed here include all brake lines, the pressure reservoir for the air suspension that is available as an optional feature, and the fuel tank. On the way to the exterior line, the vehicle is now returned to the lift table as a mode of conveyance so that assembly tasks can be performed more ergonomically.
Exterior lines 1 and 2: Windscreen and rear windscreen are fitted by robots in a fully automatic process. In addition, the vehicles are fitted with floor carpeting, the wiper system, the electrically swivelling tow bar unit, side airbags, the battery, and the Porsche badge on the bonnet.
Engine build-up: The next step is what is known as Engine build-up or Engine pre-assembly. The engines and transmissions are fed via a side arm into the assembly process. The main work during Engine build-up is in flanging the transmission and laying the cable line. This is followed by components such as the clutch disc in automatic transmissions, the starter, and the air conditioning compressor. Towards the end of engine pre-assembly, the lambda probes are connected. The entire vehicle underbody is finished and conveyed on large module carriers or driverless transport systems up to the marriage. In this phase, the bodies are still separate from the vehicle underbody.
Chassis build-up: After Engine build-up, the subsequent chassis build-up involves mounting parts such as the propshaft and drive shafts. The first cycles are used to preconfigure the suspension and axles on the large module carrier. In the next cycle, the front silencers are installed, then the propshaft is connected,and finally the drive shafts are integrated.
Mixed line: The most spectacular and best known station in any vehicle assembly process is the marriage – merging of the chassis and power train with the now completely assembled body. This marriage happens on the mixed line in Leipzig. Mixed, because for the first time all three Porsche model series – the Macan, Cayenne and Panamera – take the same route through identical stations. The assembled bodies arrive at the marriage process from a decoupling module via an electric overhead conveyor and are lowered down to the assembly line from above. This is when the Cayenne enters the assembly line.
Marriage: The large module carrier moves under the structure, and then to the marriage. The superstructure and the underbody are then automatically joined by screw fastening. In addition, the suspension is screwed into the domes manually. Afterwards, the Porsche is passed back from the electrified monorail to the plate line.
Assembly line trays 1 and 2: After the vehicles have been placed onto the assembly line tray belt, the interior assembly is completed and the centre console and seats are mounted. Then the cars receive their front-end modules. On assembly line tray 2, employees mount previously completed doors onto the relevant vehicle again and perform quality control.
Final assembly line: On the final assembly line, final tasks include finishing the wheel wells and filling the vehicle with fuel, brake fluid, coolant and windscreen cleaning fluid. Finally, the tyres are mounted to the wheel rims, and the Macan, Cayenne and Panamera can stand on their own four wheels for the first time in their automotive lives.
Testing area and finishing: The final assembly cycles are used for start-up, testing and final inspection of the new vehicle. One of the first steps performed here is what is known as ‘parameterisation’ (reading error memory, flash and coding operations, learning, calibration and adaptation operations). Driving functions such as braking are checked on a roller testing station. In addition, an employee starts the engine for the first time. Final adjustments are made to the chassis and headlights, and the driver assistance systems are calibrated. Then, on a short test track, the cars must demonstrate that all relevant components operate perfectly in action. Afterwards, the car exterior is washed and a sealing test is performed at the same time. Everything ready now for the final inspection.
Production system: Manufacturing in the customer cycle
The entire production at the Leipzig factory is based on the Porsche production system. It was developed on the basis of the four principles of ‘lean production’. One of these is the so-called flow principle. That is, using intelligent logistics and IT systems, all value-creating processes are networked with one another. The production steps and materials they require generate the flow of value-creating activities. Another pillar is the cycle principle. Porsche manufactures according to the ‘customer cycle’, which establishes a certain cycle that results in production volumes. This cycle is the driver for all production and logistics processes during the production of a Porsche. With the pull principle, employees in the assembly cyclically ‘pull’ materials from the logistics supply centres. In turn, logistics only issues production releases to suppliers for the quantities of vehicle parts needed to meet the imminent supply demands of production in order to avoid overproduction and unnecessary buffers. The zero errors principle is assurance of stable processes and error-free products.
Centre of Excellence: All specialists available at all times
In order to improve processes continuously and to solve problems quickly, Centres of Excellence have been integrated into Leipzig in the body shop, the paint shop and assembly. Experts representing disciplines in the respective areas are based in these offices located directly in the production areas. In the underbody section, 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 Centre of Excellence in the body shop. The four specialists have the expertise to solve this problem quickly.
Quality centre: Consolidation of all aspects of vehicle optimisation at one location
To ensure the highest quality, Porsche brings together all areas of vehicle optimisation in a new 6,000 sq. m quality centre with ten measuring machines. Around 150 employees work here. This includes the master jig/cubing area, where sheet metal parts of the bodywork and mechanical parts are tested, tuned and prepared for series production. A pilot hall to test assemble expansion-level vehicles is integrated in the new quality centre. A new surface treatment centre was built in addition to the new body shop. All external skin panels are visually evaluated and rated here for the Panamera and Macan models. The works have a total of 23 in-line measuring machines and two series measuring rooms to ensure the dimensions of the bodies are completely accurate. With all of this infrastructure, the established quality processes, and the efforts of all staff, this site is well positioned for the future.