Major improvements in filament fusion and laser sintering using polymer solutions are being demonstrated

PEEK polymer pioneer Victrex is preparing newly developed materials for Additive Manufacturing (AM). The first of these is a high strength material for laser sintering (LS) which attains lower refresh rates, resulting in improved recycling for unsintered powder. The second is a filament with better Z-strength than existing PolyArylEtherKetone (PAEK) materials and better printability for filament fusion (FF). The detailed technical results are expected to be presented at the bi-annual Additive Manufacturing conference of the University of Exeter Centre for Additive Layer Manufacturing (CALM), in September 2018.

The PAEK incumbent materials on the market today, although used in some AM applications, were designed for conventional manufacturing methods, such as machining and injection moulding. Because of this, they have some features that aren’t optimal for AM processes. A first generation of PAEK material for Laser Sintering can only be recycled in a very low extent and required nearly full refresh of the printing bed with new powder, and PEEK filaments available for FF have poor interlayer bonding, leading to a loss in Z-strength.

New polymer grades developed by Victrex have shown encouragingly low refresh rates with similar mechanical properties in LS, and in FF good mechanical properties and printability.

John Grasmeder, chief scientist at Victrex explains: “Breakthrough technology is paving the way for an exciting future for Additive Manufacturing PAEK. The powder recycle work for LS, using the new Victrex development polymer grades has gone very well, with no measurable loss of properties when test components were made from partially recycled powder. We believe it will be possible to re-use all of the non-sintered powder that is recovered after a build run. This will result in a significant reduction in material costs compared to current PAEK materials where up to 40% of the polymer is wasted and cannot be recycled.”

Victrex is leading a consortium of companies and institutions and was awarded funding from Innovate UK, the UK’s agency for innovation, in 2016 to carry out intensive pioneering research and development to advance AM technologies, in particular high-temperature, affordable polymer composites for AM aerospace applications. The other members of the consortium are Airbus Group Innovations, EOS, University of Exeter CALM, E3D-Online, HiETA Technologies, South West Metal Finishing, and 3T-RPD.

The new VICTREX PAEK filament and powder tie in with technologies developed by other members of this Innovate UK project. EOS has recently released a new automation-ready manufacturing platform for laser sintering of plastic parts on an industrial scale (EOS P 500) with the capability to print high-performance polymers at high temperatures. Selected materials of the consortium are evaluated at EOS R&D facilities for processability on current EOS systems as well as for use with the EOS P 500 platforms. Victrex is planning to continue pre-commercial testing of a new PAEK filament product in conjunction with consortium partner E3D, who recently commercially released a water-cooled filament extruder head especially optimised for this new PAEK filament.

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Engineering Materials

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