What is print resolution?
There are two types of resolution when it comes to 3D printing:
- Horizontal (XY) resolution – the smallest individual element a 3D printer can intentionally create on a two-dimensional scene
- Vertical resolution (layer thickness/height) – the smallest thickness of a layer
FDM printers
FDM printers print 2D patterns layer by layer through a nozzle to create a 3D model. The filament used for this type of printing is a thermoplastic material, which is melted or softened and extruded from the printer’s head. The printer’s computer controls the movement of the nozzle across the X and Y axes (based on the model design) while forcing the filament onto the building plate. After the layer is completed, the bed (or the printer’s head) shifts along the Z-axis by a defined distance, and printing of the next layer in the XY-axis starts.
The horizontal resolution in FDM printers
The control over the extrusion width affects the horizontal resolution. Factors impacting the XY resolution for FDM printers are the nozzle width, the used material, and the mechanics of the technology. The nozzle width and the melted filament’s bead size influence the spreading of the material and control the contours of the print. The mechanics of the technology almost entirely depend on mechanical motion to shape and build up the 3D model. Therefore the coordination of all the moving parts and their right calibration will impact the precision of the stepper motor and consequently the resolution. The precision of the stepper motor controls the distance the printer’s head can move (the step). The smaller the step, the higher the resolution of the print. This resolution is crucial when printing models that are meant to fit the exact measurements. A high horizontal resolution grants that the XY dimensions specified in the 3D model are printed accordingly.
The vertical resolution in FDM printers
The stepper motor that controls the movement along the height (the Z-axis) and the nozzle diameter influence the vertical resolution. The smaller these values the higher the resolution.
The nozzle diameter determines the thickness of the extruded filament. The smaller the nozzle, the thinner the line of the filament, and therefore the smaller the layer height. A large nozzle will result in a thicker line of the extruded filament and a larger layer height. In theory, this parameter can be adjusted, as the nozzle size shouldn’t limit how low the extruded filament diameter can be, but it shouldn’t exceed 80% of the nozzle diameter.
Other factors are the material properties. Rheological factors depend on the types of materials and added particles. The final shape of the line of the filament is influenced by many physical aspects. Understanding it can help in choosing the right printer parameters such as temperature. The temperature of the nozzle influences the adhesive properties, stacking performance, and flow rate of the filament. If the temperature is too low the material’s viscosity increases, which as a result slows down the extrusion speed. Conversely, a high temperature makes the material more liquid-like, reducing viscosity and increasing flow, which can lead to imprecise extrusion.
A higher vertical resolution results in smoother surfaces and allows more details to be visible on the model. This factor should be especially considered when printing objects with curved or sloping surfaces. However, a small layer height indicates, that more layers are needed to print an object of a particular size. This crucially affects the print time.
Improving FDM 3D printer resolution can be done by ensuring the printer is well calibrated, using a finer nozzle and lowering the layer thickness, slowing down the print speed, and using high-quality printing material.
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