Metal process

Renault files patents for the manufacturing process of a plastic sedan

Hatchback plastic rear doors have been used on Renault vehicles for several years [and also by rival Citroen, starting in 1982 with the BX] to reduce overall weight. Now, the recently launched Mégane E-Tech Electric has a new design that is technically simpler than before. The combination of a new design with a new industrial plastic injection process makes it possible to eliminate certain metal supports and reduce the number of parts to be manufactured.

The combination of product design, numerical simulations and plastic injection production engineering was first used for the Eolab prototype which aimed to reduce vehicle weight to an absolute minimum and fuel consumption to only one litre/100 km.

The various inventions used for the new tailgate have led the manufacturer to file two patents which will also be used on seven other new models, such as the Austral.

“Combining the use of plastic with the ‘fluid vein’ innovation, we had to completely rethink the design of the tailgate door. Quite a challenge, but now… we have a leg up on the competition,” said Herve Maine, plastic injection process specialist in the automaker’s production engineering and vehicle prototype division.

Benefits of innovation

The advantages over the previous generation of plastic tailgate doors include, according to Renault: Reduced weight of 4.1 kg/m2, a reduction of 5 kg (20%) per part; reduced cost of “a few tens” of euros per part; a more rigid door and fewer parts needed for assembly (25), in a simpler process.

New process

The overall structure has been reinforced with water injection molding. The new process involves using injected water to dig a groove. The hollow groove acts as a stiffening beam. The plastic removed by the water injection process is then reused to make other parts, reducing overall plastic usage.