What is a high resolution 3D printer? The simplest definition might be a machine that can additively manufacture parts with low minimum feature sizes on the XY plane and the Z-axis. “Low” and “high” are relative terms, however, and neither indicates a specific measurement or even a range of values. Minimum feature sizes aren’t the same as minimum part sizes either, and size – like accuracy and precision – is different than resolution. If you need a high resolution 3D printer then, it’s worth taking a closer look at some definitions and then a few examples of equipment.
To understand resolution, it helps to start with what it’s not. Although the terms are sometimes used interchangeably, resolution is not the same as either accuracy or precision. Let’s use a game of darts to illustrate this point. Accuracy is the closeness of a measurement to the true value (i.e., the bullseye in the target). If a dart hits the center of the bullseye, then the shot was accurate. Precision, on the other hand, is about reproducibility (i.e., hitting the same spot on the target every time). That’s not the same thing.
A group of darts may all land in the same place, but the player won’t win the game if that place is an outer ring on the target. As the diagram below shows, there are four possible scenarios with accuracy and precision. Hitting the target’s bullseye is always the goal, but only high accuracy and high precision are a winning combination. Moreover, neither accuracy nor precision is the same as resolution, which would be the smallest amount of distance that a player can detect between darts that have landed.
Resolution is also different than object size or build volume. Here, it’s important to consider scale. Macroscale 3D printers produce geometries that are measured in millimeters (mm) and above, including centimeters (cm). Some macroscale 3D printers are able to produce features that are “small” relative to a part’s size, but “small” at the macroscale level has a different order of magnitude than at the microscale or the nanoscale. Both microscale and nanoscale 3D printers can produce small parts, but microscale geometry is measured in micrometers (µm) while nanometer geometry is measured in nanometers (nm). These units of measure are very different since a micrometer is a thousand times larger than a nanometer.
With a high resolution 3D printer, the ability to achieve relatively small, or low, minimum feature sizes is critical. Yet, there are also differences between 3D printing technologies to consider. With fused deposition modeling (FDM), resolution is a function of the smallest movement that the extruder can make within a single layer. With stereolithography (SLA), it’s a function of the spot size of the beam of ultraviolet (UV) light. Projection stereolithography (PµSL), a form of SLA printing, uses a flash of UV light to cause the rapid photopolymerization of an entire layer of liquid resin instead. It also provides high resolution.