Voxelfill - Layer Crossing 3D Printing

Anisotropic behaviour is a known limitation of additive manufactured parts, that is caused by the layer wise material deposition process. Across build direction (Z axis), extrusion (MEX) parts show a decreased tensile and bending strength as well as a brittle material behaviour. The aim for the patented „Voxelfill“ process is, to overcome this limitations to produce functional parts.
A strategy was developed, that increases the mechanical properties and the economic aspects. A base structure is printed for the perimeters and the grid structure, that will create the volume chambers (Voxel), e.g. 3D honeycombs. Afterwards thermoplastic material is injected into the Voxels layer crossing every certain number of layers. It is relevant for the increasing of strength and elasticity that per filling step, just half of the Voxels are filled, what will result in a Z-offset of the adjoining Voxels. This causes a shift of the breaking line under stress. The development pro-cess contains the pore free filling of the Voxel as well as the investigation of the thermal bonding between the injected material and the grid. Mechanical tensile strength tests according to ISO 527-2 are carried out to investigate the resulting strength. Additional to unfilled materials like PETG, ABS and PEI, fibre reinforced materials like PA6 GF30 a predestined for the process. The layer crossing injection of fill material makes it possible to insert fibres in Z direction in 3D printed parts.

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