GAZ Group, based in Nizhny Novgorod, is a production partner of Daimler for Mercedes-Benz Sprinter models intended for the Russian market. The partnership was announced in the middle of last year and production commenced this summer; the first Sprinter Classics rolled off Nizhny’s production line on July 15.

The Sprinter Classic is billed as a robust product that is tailored to the needs of the Russian market and sold at an affordable entry-level price. It uses the proven Sprinter platform, of which more than 1.5 million units have been produced to date. The vehicle is being positioned in Russia’s growing mid-priced segment for large vans and started appearing in the country’s showrooms in September.

As part of its partnership with GAZ, Daimler is investing more than €100 million in product modification, production facilities and the sales network. GAZ is investing more than €90 million in the project.

Nizhny Novgorod represents only one aspect of the partnership. The GAZ facility in Yaroslavl is manufacturing Mercedes-Benz OM646 four-cylinder diesel engines for installation in the new vehicles; GAZ set up a new assembly plant there late in 2011. “Already at the start of production, the Sprinter Classic boasts a localisation rate of over 20%,” states Volker Mornhinweg, head of Mercedes-Benz Vans. “We will steadily increase this figure for all of the parts and components.”

Investing in a new paintshop

However, none of these vehicles could be coated in any of the existing paint plants operated by GAZ because of constraints imposed by available capacity and body dimensions. GAZ thus recognised that it would need to invest in a new paintshop to ensure that it could fulfil its side of the deal, even while it was still involved in negotiations with Daimler. Indeed, the move was intended to have even broader implications, since GAZ also saw the opportunity to use the projected new system to paint its own GAZelle Next light commercial vehicles.

GAZ approached three plant engineering companies about the project, including German company Eisenmann. In collaboration with the vehicle manufacturer's project leaders, Eisenmann developed a plant concept based on Daimler's specifications for materials, applications and quality - which won it the contract.

The original concept envisaged by GAZ did, however, undergo some changes during these preliminary stages. Initially, the plant was intended to be housed in two adjacent hall areas, one of which was already in use as a sheet metal shop. But after a project planning and tendering stage lasting around one year, GAZ took the decision to integrate the paint plant entirely into the sheet metal hall, which would then be fully renovated. The necessary alterations to the plant layout, which were implemented very quickly, also allowed the plant to become more user-friendly, easy to maintain and efficient.

Current operations

In its present configuration, the installation enables optimal pre-treatment and electro-coating. Vehicle bodies come from the body shell shop and are transferred to an electrified monorail system by means of hoisting belts at a transfer station. The belts are driven by two motors and are equipped with suspension gear which locks the skid to the body.

The conveyor system then transports the bodies over the pre-treatment and electro-coating basins and lowers them into the various processing baths. Very importantly for final product quality, the dual lifting drives of the electrified monorail system trolleys allow bodies to be dipped into the respective basins in the ideal position for coating. This not only achieves optimal filling and draining of paint but also reduces the transfer of material from basin to basin. The sizes of the dip basins are specified precisely to the products and processes. This results in significant material savings during both filling and operation.

After the electro-coating process, the monorail system places the skid on a roller conveyor which transports it to the PVC line for sealing operations. The bodies are transferred to a suspended skid for underbody sealing.

Differing carrier concepts

During the design of the plant, the large variety of van and truck cab dimensions involved was not the only factor that had to be taken into consideration. Different carrier concepts also had to be implemented. For example, Sprinter models are transported using wrap-around suspension arms whereas GAZ vehicles are conveyed using chains. Therefore, it was necessary for both suspension arms and chains to be mounted on the suspension skid so that it could pick up either type of vehicle body.

These processes place considerable demands on delivery to the point of manufacturing liquid materials. To this end, four innovative Jupiter high-pressure pumps with a capacity of 1,100cm3 per double stroke and 28 Galaxy pressure controllers are used to supply seam sealant and underbody sealant. These new pumps and controllers were designed by Eisenmann especially for processing highly viscous materials which require extremely powerful systems with high pumping capacities and material pressures. These high-specification units also provide for economies elsewhere in the overall system, since the pumps dispense with the need for costly pressure boosting stations. This results in savings in initial investment and operating costs, not least through enhanced energy efficiency.

In addition, the configuration of the hardware provides specific benefits. The design of the housing for the controllers, which utilises high-strength aluminium, allows various modular assemblies for both the supply pressure and back pressure regulators to be integrated as desired. This means that all feasible application requirements can be covered. The pumps and controllers are also extremely easy to maintain.

On the actual painting line, the solvent-based paint is applied in a conventional process using robots supplied by GAZ; Eisenmann took on the task of interface co-ordination. A thermal post-combustion system was installed for exhaust air purification. After painting, the bodies are transported to a sequence buffer which was also provided by Eisenmann. From there, the bodies are retrieved by final assembly and sent to the planned assembly sequence.

Final assembly

GAZ also opted for Eisenmann plant components when equipping the final assembly line, including conveyor technology for chassis, marriage and final assembly operations. The deciding factors in this instance were reference projects in Russia and a final assembly project for Sprinter models which was implemented in the US. Eisenmann plant engineers provided a chassis and final assembly line as well as a marriage shuttle.

The chassis line has a heavy-duty monorail overhead conveyor with a total of 17 trolleys equipped with patented chain hoisting gear. A crucial factor governing the choice of this configuration is that chain hoisting gear is lighter than conventional scissor lifts and can be folded together more tightly. Consequently, they can be fitted in comparatively low-ceilinged assembly halls. So despite widely varying body lengths and resultant differences in their centres of gravity, just one type of hanger is required to transport the bodies along the chassis line without any need to adjust the mounting.