Cycle times, costs, weight reduction … At the Technocampus Composites of Nantes, France, the CETIM research center is leading the effort to convince the French automotive industry to use composites materials.
Original article in French published by Manuel Moragues in the USINE NOUVELLE magazine n°3506 - March, 9th 2017.
CETIM workshop does not look anything special. At the very best, it looks like a patched sock that was crushed under a steamroller. A patchwork of geometric shapes roughly cut… However, it represents a breakthrough innovation, baptised QSP (Quilted Stratum Process or multi-thickness patch laying process), which could allow composites to earn their way into the automotive industry.The flat preform exposed at the
“This process – JEC innovation award in 2015 and 2016, ed – is one step ahead of all the other composites manufacturing solutions, says Christophe Champenois, Manager of the Polymer and Composite activity division at CETIM. QSP has become a benchmark, known worldwide, far better than the CETIM!”
A production pilot line was developed in 2013 by the CETIM and three SMEs: PINETTE P.E.I., LOIRETECH and COMPOSE. This line can be visited at the Technocampus Composites research center of Nantes. This R&D center, opened in 2009, is 80% dedicated to the aeronautics industry, in particular for Airbus which as a manufacturing plant near the center.
A composite part manufacturing process targeting the automotive industry
Yet, the CETIM targets the automotive industry: “We aim to answer the most demanding specifications, those of the automotive industry, insists Christophe Champenois, that is to say the combination of short cycle time – low costs – high performances”. The final goal is to reach high-rate and low-cost production for composites parts enabling to reduce vehicles weight. A real difference with the aeronautics industry, where we can find higher production costs - with cycle times of 1 hour and more - but easier to absorb, thanks to the fuel savings made just by saving 1 kg.
“It represents a major issue for the mechanical engineering sector – or materials, ed -", continues Christophe Champenois. Because of the implementation of increasingly stringent emission standards, automakers that must reduce vehicles weight will have to use composite materials. With their large sedans, German automakers are the first to be affected. But they are also at the forefront of composites manufacturing solution development. French subcontractors might lose markets when the entire sector will embrace composites. “Through innovation and training, we want to turn this threat into an opportunity.”
Short cycle times – low costs – high performances, let’s go with the QSP ® process. First of all, the QSP ® relies on thermoplastics, less use to produce structural parts until then, but faster to manufacture compared with thermosets that are used for planes structures.
Then, since this material is expensive, it was necessary to produce net shape parts in order to reduce the scrap rate at the minimum. Manufacturing net shape parts solves this problem by eliminating milling operations & material excesses.
To do so, the patchwork is the best solution. It consists in a 2D+ preform composed by patches (flat elements with simple shapes and the same thickness) that are judiciously placed in order to get a final part - through stamp forming – with the right thicknesses & the required mechanical properties. Indeed, an optimized design based on complex algorithms lies behind the patched sock.
Following this approach, the raw material from which patches are cut become a semi-finished & semi-standard product: a composite tape far cheaper than the Organo sheets currently available on the market.
Two to Three meters of composites per minute
That is the theory. In the practical application, CETIM produces this tape by thermoplastic pultrusion. Dozens of fiberglass rovings are pulled through the die of an extruder where molten polymer pellets will impregnate the fibers. The resulting tape is continuously pulled. The main challenge? The speed.
“We already reach a competitive rate of two to three meters per minute. Our aim is to reach 5 meters. That would give us the opportunity to penetrate the market”, predicts Christophe Champenois. With a cutting speed of 500 millimeters per second, the - patented - cutting unit developed with PINETTE P.E.I. follow the pace.
The heart of QSP innovation lies in the preform assembly & heating systems - both patented – developed with the three SMEs.
A high speed robot system is used to pick, place and weld the patches on a table. “The speed and the repeatability of this machine are unique”, says Christophe Champenois.
The heating phase - divided in two steps - starts in a conduction oven controlled by an infrared camera and is finalized in something similar to a “giant horizontal toaster”. It ensures to obtain a homogeneous temperature on a multi-thickness part. A real challenge.
No time to lose, a robot ensures hot preform high speed transfer to the stamping press, where patented tools with retractable ejector pins allow to hold the preform without any deformation. The part is ready after being formed in the press. The 2D+ preform became a net shape part.
Cycle time? Less than ninety seconds!
The QSP production line evolves constantly. It has been extended to produce fully functional parts in one shot: reinforcements by overmolding & holes with metal inserts are done during the stamping step.
CETIM will present the latest part resulting from the QSP process at the JEC WORLD, from march 14th to 16th at the exhibition centre of Paris Nord Villepinte: a bumper beam allowing a mass reduction of 30 % (1 kilo) for 10 euros, compared with 8 euros for a steel bumper beam. A QSP line can produce 300 000 units per year. Therefore, the QSP solution meets the requirements of the automotive industry.