On a recent trip to Northern Spain, CAR road test engineer Peter Palm visited the Mercedes-Benz assembly plant in Vitoria… He gives us an insider’s view.
Tracing the source of the Mercedes-Benz Vito's name is quite simple - the plant where the truck is manufactured is situated in Vitoria, in the Basque region of Spain. This factory is no newcomer to the manufacturing scene either. It began its life in 1954 when the DKW F 89 L van was produced, complete with front-wheel drive and a 700 cm3 two-stroke engine. When Daimler-Benz acquired Auto Union in 1958, the factory began the progressive switch to Mercedes-Benz vehicles, notwithstanding a period under Volkswagen's ownership.
The first version of the Vito (incidentally with front-wheel drive) was introduced in 1995 and the plant ran three shifts per day to meet the demand. The new version was introduced in 2003 and coincided with a decision to double the plant's size.
At present, daily production is 450 vehicles using two nine-hour shifts per day. In theory, production could be increased to 140 000 vehicles per year if the plant ran three shifts a day.
The factory is split into three areas – body shop, paint shop and final assembly. The total staff complement of 3 650 is assisted by 650 robots used mainly in the body shop, where the different body sizes have led to a 93 per cent reliance on robot assembly.
Each Vito can be configured from a huge range of options... Standard roof or high roof, three body lengths on two wheelbases, three diesel and two petrol options, side and rear windows or fixed steel panels, rear swing doors or rear hatch are options available to suit different needs.
Because a variety of window options are available, body panels are pressed without openings, reducing inventory levels. Lasers are used to cut window apertures to specific sizes, to weld the roof to the side panels, and to perform precise measurement checks.
The painting of motor vehicles has progressed over the last decade, with a greater emphasis on the environment. All excess fluids and chemicals are recovered, refiltered and re-used, and toxic additives have been eliminated with the switch from solvent- to water-based paints. At this factory, though, the final switch to a water-based top coat has yet to be made.
The sequence of body treatment starts with degreasing, adding a zinc primer, a phosphate coating, a cataphoretic immersion coat and a filler coat before the final coat is sprayed. The only painting done by hand is the final coat in the rear load bay and engine compartment. Underseal and seam-sealing in difficult-to-reach areas is also considered too tricky for robots to perform.
Cleanliness is vital, and all the personnel are clothed in protective garments. The air is filtered and pressurised throughout, and the temperature and humidity are continuously monitored and controlled.
The total thickness of paint adds up to about 95 microns and adds approximately 25 kg to the total mass of the vehicle. A staggering total of 147 colours can at present be accommodated at this plant, and since small businesses may want specific colours to suit their needs, one does see the odd orange or pink body shells adding colour to the assembly line.
The welded and colour-finished body shells are then transferred under-cover to the largest section of the plant, the final assembly shop. This uses a "U" shaped production line with many access points for the sub-assemblies to be delivered, not only "just-in-time", but also "just-in-sequence" so that the minimal amount of ferrying and storing of items is necessary.
Final assembly operations requiring dexterity are performed by hand and these modules include front and rear axles and the complete front bumper with headlights, grille and radiator. Due to the dexterity needed by these assembly operations, this shop employs the largest workforce with about 1 100 staff.
Robots fit the large and hefty facia with instrument panel, and the windscreen and side windows. To provide unhindered access to the interiors, all the doors are removed and only re-fitted once all assembly activities have been completed. The last stage involves filling up with all relevant fluids such as brake fluid, air-con refrigerant, washer bottles and fuel, followed by a thorough inspection that includes a chassis dynamometer run, electronics check, a leak test on sunroof-equipped models plus functional and visual checks. Then it's off to the shipyard for delivery.
As a parting note, perhaps the most impressive sight in such a precision-intensive factory is watching the massive ABB robot arms swinging back and forth and missing concrete pillars and roof trusses by a matter of millimetres. How's that for accurate design and planning!
Original article from Car