We are mainly referring to the technologies that exist behind FDM 3D printers here. Those are melt deposition (FDM), stereolithography, selective laser sintering, multi-jet modeling, etc. But what are the different machine types existing for the same technology and the operation of a 3D printer?
Today, we are interested in FDM 3D printers: polar, cartesian, robotic arms, and delta.
How a polar 3D printer works
This type of printer uses the polar coordinate system. The positioning is not determined by the three cords X, Y, and Z but by an angle and a length, which means that the plate rotates and moves at the same time in only one direction. The extruder moves from top to bottom.
This setup has one great advantage. It uses only two motors, whereas Cartesian printers require at least three motors. In the long term, the polar printer is more energy efficient. It can make larger objects while using less space.
Cartesian 3D printers
These are the most common on the FDM printer market. This technology uses three axes – X, Y, and Z (the Cartesian coordinate system in mathematics) – to determine the correct positions and direction of the print head. With this type of printer, the printing plate moves typically only on the Z-axis, with the print head operating in two dimensions, in the X-Y plane. The two best-known brands on this market, Ultimaker, and Makerbot are part of this machine category.
There are differences in the way the printing plate moves; sometimes it moves along the Y-axis – as on gMax and gCreate.
3D printing with a robotic arm
Robotic arms are best known for assembling components on industrial production lines, particularly in large automotive plants. They are rarely used to extrude filament. 3D printing via these machines is still in the development stage; only a few companies use this technology for house building, for example.
However, the use of this FDM printing method increases because of the increased mobility not tied to a printing plate. The robotic arms can rotate 360° and thus allow large printing volumes. Thanks to the flexibility of the positioning of its print head, the creation of complex structures is easier. However, it should be noted that the final printing quality is not as good as on conventional Cartesian printers.
They are more and more numerous on the 3D printing market. One example is the one developed by the two Swiss students: they have developed a six-axis 3D printer based on delta technology.
These machines operate with Cartesian coordinates; their main feature is the round printing plate associated with the extruder, which is fixed at three points in the triangular structure. Each of these attachment points moves up and down, determining the position and direction of the print head.
Delta printers have been designed to speed up the printing process. The fixed printing plate is useful for specific projects. However, it is often said that this type of printer is not as accurate as a conventional Cartesian printer.