GRAiL

Additive Manufacturing AM is used to build physical models, prototypes, patterns, and
production parts in a wide variety of materials (in particular plastic, and metals) for a wide
range of markets (AppA). Components in digital format are rendered into thin horizontal
sections and using various techniques (e.g. Selective Laser Sintering (SLS), Vat
Photopolymerisation, Material Extrusion and Powder Bed Fusion) material is added layer by
layer to build the component. SLS which utilises lasers to melt layers of metal or polymer
powder on to each other (AppA) was developed in 1984 and since the patents expired and the
price and availability of these machines has dropped dramatically, further stimulating
demand. Initially, polymer SLS systems used amorphous polymers (ABS) with a broad
melting range but today almost all polymer SLS systems use crystalline polymers with a sharp
melting point (typically Nylon PA12) and the powder is melted. Unfortunately SLS polymer
properties are diminished compared to conventional extruded material.
Fibrous fillers can improve toughness but the nylon has to be compounded and then cryoground
or milled producing angular surfaces on the powder which restrict its flow
characteristics. Rapid Powders has a proprietary process whereby precipitated spherical
powders can be coated with a wide range of filler materials (including nano-fillers) and in
particular Graphene which is a desirable filler for polymer nanocomposites and improves their
mechanical properties. We propose to prove the concept of the production of a range of PA12
graphene nanocomposite powders with good flow characteristics that when melted or sintered
in a SLS machine have improved properties comparable to extruded PA12 enabling the SLS
production of finished components.