Evonik, Lehvoss launch fiber-reinforced polyamide for SLS

In cooperation with Evonik (Marl, Germany), Lehvoss (Hamburg, Germany) has developed a PA613 with compounded carbon fiber reinforcement — Luvosint PA613 9711 CF. The base polymer PA613 was designed by Evonik specifically for laser sintering. It is characterized by low moisture absorption, high temperature stability and — unlike PA6 — high process stability in laser sintering. The fiber reinforcement consists of high-strength XCF fibers, which have previously been used in Luvocom XCF products for injection molding. When it comes to powder production, approaches to particle technology were taken in order to preserve the fiber lengths in the individual particles as best as possible.

Powder bed processes, such as laser sintering, offer geometric freedom when printing components, which is necessary because the components originally designed for injection molding have complex geometries. Unfortunately, reinforced polymers in powder form are a contradiction. Fibers mixed dry into plastic powders can make do, but unbound, very thin fibers or mineral microscopically thin needles can be risky to handle from an occupational safety perspective. For this reason, they do not receive internal approval from industrial 3D printing processors.

Printing the Luvosint PA613 9711 CF requires a build chamber temperature of 195°C, which makes standard laser sintering machines suitable for processing. The material absorbs the wavelengths of CO₂, diode or fiber lasers.

“The fact that the first automotive OEMs have already qualified for spare parts production shows that we are on the right track,” says Dr. Marcus Rechberger, product manager for Luvosint at the Lehvoss Group. “Nevertheless, in laser sintering, there still needs to be a lot of willingness to innovate in order to develop even more industrially relevant material — including machines optimized for this — in order to bring industrial 3D printing into ‘series.’”