3D Printing in 5 Axes Opens Up A World of Possibilities
A sample produced via 5-axis ME: (a) during manufacture, and (b) after manufacture, Loughborough University
The physical world exists in three dimensions, and the most common form of 3D printing – called FDM or “fused deposition modelling” – attempts to build those three-dimensional objects by depositing layers of thermoplastic filaments through a heated nozzle.
Layer by layer, the object takes shape. But layered objects can be weak structurally, because the layers are generally in one direction and not reinforced.
FDM printing only goes left-to-right and back-and-forward, with a slight movement up and down at each layer. To properly lay down reinforced layers, you need to move beyond these three tool axes
That’s why five-axis printing is the biggest advancement for FDM printing since the technology began in the late 1980s. It allows layers to be interwoven and stronger, with greater definition and the ability to wrap around the object.
‘Curved Layer Deposition’
These additional axes – tilt and rotate, plus a full Z (up and down) axis – offer so many possibilities that researchers are still figuring out how to best use them, since there are no dominant methods.
Our 5AXISMAKER machines are the only affordable ones providing 5-axis printing (and milling), so researchers are employing them to figure out methods – such as in these four research papers.
One of them, “Aligning Material Extrusion Direction with Mechanical Stress via 5-Axis Tool Paths,” notes that 5-axis printing “enables the fabrication of parts without the layer-by-layer restrictions that conventional 3-axis strategies impose.”
Figure 13 - A comparison of wave springs produced via (a) 3-axis and (b) 5-axis ME
It shows an object (Figure 13a - left) that was printed via 3 axes, and another (Figure 13b- right) printed with 5. Under stress, the 5 axes-object cracked but didn’t fracture. Cracking is better than fracturing, and the implied potential is that the strength can be improved with composite material.
The paper also points out that layer-by-layer additive manufacturing, as used in conventional FDM printing, has such limitations as “loss of dimensional accuracy, stair stepping effect (leading to poor surface finish), and anisotropic mechanical properties.” Anisotropic properties are ones that have different values in different directions, such as a wood that is stronger with the grain than against it.
The researchers developed a process they call “5-axis curved layer deposition,” which they found resulted in “improved surface finish” and increased strength.
Short-Fiber Carbon Filaments
As this paper indicates, 3D printing is often limited by the use of plastics. Another research paper – “Porosity in Multi-Axis Material Extrusion of Short-Fibre Composites” – has investigated the use of a plastic composite embedded with short-fiber carbon filaments.
Conventional FDM deposits a semi-liquid thermoplastic filament in layers, by heating it and then extruding it through a nozzle. But, the paper notes, FDM-printed parts “suffer from limitations such as poor surface quality and poor mechanical properties,” with a significant weakness between layers that makes them “not suitable for multidirectional stresses.”
The researchers found that the use of short-fibre reinforced composites can increase tensile strength by almost 40%, compared to pure plastic.
Spiral Printing
A third paper, “Curvature and Feature-Aware Print-Paths from Hexahedral Meshes for Additive Manufacturing,” looks at some ways to avoid limitations of layered printing in a non-reinforced thermoplastic – such as the “stair-stepping effect” – and to maximize mechanical strength by coming up with different methods for different kinds of objects.
And the fourth paper, “Helical5AM: Five Axis Parametrized Helical Additive Manufacturing,” introduces a new additive manufacturing (AM) technique designed specifically for 5-axis printing. It calls the new technique Helical5AM, and it employs spiral printing using 5 axes, instead of the traditional planar slicing used in 3-axes 3D printing.
“Helical5AM: Five Axis Parametrized Helical Additive Manufacturing,”
“…Three-axis AM systems are limited to deposit material in a single direction (i.e., along the Z-axis) unlike the five-axis AM,” the paper points out.
But, it adds, 5-axis printing offers “such freedom [that] makes it possible to decompose the CAD [computer-aided design] model of the part into complicated print-paths (i.e., volumetric covering curves of the model) which results in the (printed) parts with remarkable improvements in their mechanical properties.”
It’s clear that five-axis tooling for 3D printing offers many opportunities to advance desktop printing using FDM technology. These four research projects represent big steps toward figuring out the best ways to take advantage of the new possibilities.