A smart solution

Renault S.A.
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Combined experience to deliver a global solution for painting Renault’s third-generation Twingo.

The new Renault Twingo will be produced at the Revoz factory in Slovenia, preparation for which has involved modifications to the painting and underbody protection processes. These major challenges were overcome by a co-ordinated effort between Kremlin Rexson and Sames Technologies, sister companies in the Exel Industries Group, which combined their know-how and experience to propose a global solution.

The target for the underbody protection and sealing process was to increase productivity and quality. “For this process, Renault decided to copy the robotic solution utilising our proven Entry system that we had already provided in their paintshops in Brazil, Romania and Russia” explains Dov Chemouny, key account manager for Sames.

The installation at Revoz involves six robots equipped with spray guns to apply sealant and rocker panel protection under the car bodies. The correct application pressure and the circulation of material are delivered through the use of Kremlin Rexson Quatro 40C750 pumps. Kremlin Rexon claims that the Quattro pumps provide a balanced flow rate and the ability to circulate the material back from the gun. “The Streamloop capability adjusts the flow rate to put the right dose in the right place to ensure top quality,” reports Frederic Charnoz, key account manager for Kremlin Rexson.

The installation was thoroughly tested out beforehand. “The robotic trajectories were programmed off-line and used for real conditions validation trials,” says Chemouny. “Furthermore, a strong partnership with the material manufacturer allowed us to surpass Renault’s expectations about cycle time, finishing quality and material savings.”

As far as the painting process is concerned, the large product portfolio at Revoz involves plenty of colours – in fact up to 19 – with a specific adaptation dedicated to Smart cars, in that doors can have a different colour from the body. The solution involves the use of a skid which carries only doors and enables them to be painted separately from the body.

Reducing VOCs

Another major consideration was the need to reduce VOC emissions by switching from solvent-based paint to waterborne technology, requiring the two companies to specify an appropriate painting process. One feature of this method is that the mono component layer is coloured with a special red clearcoat for high-finish effect.

Frederic Charnoz details the paint supply system: “Twenty-five electric pumps for paint and four pneumatic pumps for solvent have been installed in the kitchen room. Then, the material circulates through 8.4km of hoses to eight manual and three robotic paint stations.” For interior cut-ins, the manual stations each comprise 19 M22 HPA guns, selected on the grounds of efficiency. Meanwhile, all exterior surfaces are painted by robots equipped with electrostatic bell atomisers.

Dov Chemouny says there were specific reasons behind the proposal to use the Accubell 709 Evo sprayer. “With the paint canister inside the sprayer, the Accubell solution is the latest internal charge technology able to reduce waterborne paint consumption.” Chemouny adds that the Accubell system combines three functions: atomising, colour changing and dosing. For these last two functions, he states, the Accubell system boasts a superior performance to a conventional process arm composed of a colour change block and a gearpump. “For the Revoz plant, as plastic doors and steel car bodies are painted on the same line, the new filling station helps to reduce colour change to only 12 seconds with just 12cc of paint lost,” he states.

Renault already uses Accubell technology; Chemouny confirms that 16 Accubell 608s are still painting Scénic interior cut-ins at Douai, France. But Revoz also uses a new range of bellcups.

These new EX80 80cm magnetic bellcups have a wider shape to improve atomisation. A key feature is a new air shroud designed to increase the pattern width up to 500mm, which improves the spraying efficiency. A higher spraying efficiency value means that fewer robots are required within the cycle time.

A smart solution
 

Quattro 40C750 pumps ensure suitable application pressure and circulation of material

 

Sames Accubell 709 Evo equipment stands ready to paint