Markforged Eiger offers two distinct methods for reinforcing continuous fibres in 3D printed parts: Isotropic fiber and Concentric fiber. Let's delve into each of them in more detail.
The Concentric fill reinforcement pattern strengthens a specific number of outer shells, which are the outerwalls of the part within its contours. This reinforcement helps prevent the part from bending around the Z-axis. Eiger allows users to customise the number of concentric rings of fiber applied to the part. However, this pattern takes longer to complete because the printhead's movements are no longer linear. As a result, the speed is reduced to ensure accurate tool path tracking around curves.
On the other hand, the Isotropic fiber reinforcement pattern places a linear fiber fill pattern within the part. This emulates the individual unidirectional layers found in traditional laminated composites, resembling the layers within a conventional composite material. This pattern effectively creates a unidirectional fiber sheet on each layer where it is applied by aligning all the fibers parallel to each other in a singular orientation. When the fiber path reaches the edge of the part, it makes a 180-degree turn. Furthermore, Eiger automatically rotates subsequent isotropic fiber layers at 45-degree angles relative to the preceding layer's fiber orientation. This type of fiber routing is particularly effective in resisting bending in the XY plane. Any bending forces applied in that plane generate tensile loads on some of the fibers, ensuring their strength in tension. While the isotropic fiber reinforcement is excellent for reinforcing the entire plane of each part, it is a more expensive option for creating strong parts.
In conclusion, the fiber reinforcement patterns are designed to enhance the strength of the parts and should be selected based on an assessment of the forces acting on the part.
