La plume de Mecaplast’s trim cuts vehicle weight by 7kg

A project involving injection moulder Mecaplast and other companies based in France is seeking to commercialise a new technology for producing foamed polypropylene parts for automotive interior and exterior trim.

Mecaplast, headquartered in Monaco, said it has patented the process, which relies on a combination of moving mould cores, a chemical blowing agent, and lightweight reinforcing fillers. The technology can cut the weight of interior and exterior trim parts by between 30 and 50%, it said.

The project to industrialise the process is sponsored by the French government and is called Plume (meaning “feather” in French). The two-year project starts in September and will have a total budget of €2.4m.

Elsa Germain, research and innovation engineer at Mecaplast, said: “Incorporation of parts made by the Plume process could lead to a total vehicle weight reduction of between 5 and 7kg. This will have an important knock-on effect on fuel consumption, with resulting carbon dioxide emissions falling by around 0.5-0.7g/km.”

Mecaplast said the process is similar to one already used in Japan for production of parts used by automotive companies including Honda and Toyota. It said: “However, that process has some limitations, especially in terms of surface finish, since the parts are made with talc-filled polypropylene. The Plume process will use newly-developed compounds that contain little or no talc.”

Sumika Polymer Compounds, part of Sumitomo Chemical Group company, will partner Mecaplast from its base in Saint-Martin de Crau, France.

The compounds developed exclusively for the Plume process will incorporate new reinforcing fillers that provide an improved surface quality and help reduce part weight by up to 7%, without loss of mechanical properties. Compounds with various fillers will be trialled during the Plume project.

The new compounds are expected to have a melt flow index of more than 50 g/10 min. This high MFI “is critical for the success of the Plume process,” said Mecaplast.

The company described its new process: “In the Plume process, material is injected into a mould with moving walls that are initially in the forward position. Once all the material has been injected, and the skins of the part have solidified, the walls retract.

“This lowers the pressure in the mould cavity, and chemical blowing agent, until now dissolved in the melt, comes out of solution in the areas of the part that are still fluid to create a cellular structure that fills the newly created space. The foaming process on its own (disregarding compound formulation) enables a weight reduction in the part of at least 30%, compared to a conventional solid moulding.”

The other project partners are: mould maker Cero, based in Nantes; polymer science research laboratory IMP at the University of Saint-Etienne; and Sophia Antipolis-based Cemef, a research laboratory from Mines ParisTech, associated with CNRS, with expertise in process simulation.

Cemef will look at melt rheology and its effects on the process and it will also carry out analysis of the microstructures created by the chemical foaming. IMP-UJM will study the mechanical behaviour of parts made under various conditions.

Mecaplast said process trials will focus on two components, a tailgate interior trim and exterior beltline mouldings. The beltline mouldings will be produced in two versions, one with a grained surface that will require no painting and another that will be paintable.

Mecaplast has annual turnover of €692m and employs more than 5,500 staff in 15 countries. It was ranked 15th in the 2011 European Plastics News Data Report on Europe’s 50 Top Injection Moulders.

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