Extruders are the number one reason why 3d printing technology has become economical and reachable to many. Out of all the 3D printing technologies, FDM (Fusion deposition Modeling) / FFD (Fused Filament deposition) has been a widely used technology which is primarily made possible by use of extruders.
How 3D printer extruder works?
An extruder is an assembly of tools typically mounted on the top of a print bed and receives the material filament, liquefies it by heating it up and then extrudes through a small diameter nozzle to get the accuracy of layers in the printing process. This extruder is moved in different directions using X,Y and Z motion controllers where the flow control mechanism in the extruder also accepts the signal codes of the program and finally creates the 3D model as per the fed program. Since the material filaments being used for 3D printing are typically thermoplastics or those which will liquefy at higher temperatures, it will be easy to extrude it and create the desired shapes.
A typical extruder will have a filament guide, a heater, a nozzle and ancillaries such as a cooling fan. Filament guide with the help of rollers ensure that the filament is passed to the hot end without any folding or tangling. The heater section heats up the filament material to the liquid form so as to fill up the nozzle section with the hot material. The nozzle acts as a “plunger” extruding the hot metal into the print bed where it cools off to assume the extruded form of layer.
LEGEND: 1– 3D Printer Extruder, 2 – deposited material (modeled part), 3 – controlled movable table. Courtesy : Wikipedia
Extruder – Heart of 3D Printing
An extruder is one of the most vital parts of the 3D Printer because it is ultimately responsible for the resolution / intricacies of the 3D print and hence the quality of the model. The minimum thickness of material the extruder can extrude defines the resolution of the 3D printer. Better the quality of the extruder of the 3D printer, better the 3D print quality and resolution.
Types of Extruders
There are various types of 3D printing extruders available. Some are open source and some are patented. A few 3D printers utilize patented extruders of their own to gain unique competitive advantage and some 3D printers use open source design extruders to provide flexibility of DIY for users. It entirely depends on the user’s preference on choice of the 3D printer as most of the times a user will not be choosing his own extruder unless he is a hardcore DIY guy.
Another important point to look for is the no. of extruders per printer. There are generally single and dual extruder 3D printers. As the name implies, Single extruder helps print a single kind of material of a single color. But the dual extruder 3D printer can print a model of two different materials of two different colors and give you more choices of freedom in 3D printing. Dual extruder printers are becoming increasingly popular and there are ample opportunities for us to see multiple extruder 3D printers in the near future with technology advancement and reach.
The balance of extruder design
Most of the commercial 3D printers are fitted with a 0.4 mm nozzle diameter extruder. The question that pops to mind is that why only 0.4 mm? Why not going down to 0.2 mm / 0.1 mm to get much finer prints? There has been much debate on this. The general answer that I could gather in my research is that the commercial material filaments such as ABS, PLA, etc., are found by manufacturers to be economical when manufactured into 0.8 mm diameter. The research further showed that even with utmost care taken to keep the branded filament free of impurities, the filament is prone to develop small lumps when melted due to various reasons such as temperature at transport, stored, used, etc., and the best way to deal with these issues is by keeping with a 0.4 mm diameter as anything less than this diameter may interrupt with the flow of material to be printed and hence quality of the 3D print. Also, it goes without saying that nozzle size more than 0.4 mm diameter means lower resolution and hence lower print quality. It doesn’t stand as a rule but as a guidance from experience and anything better achieved than this has a good potential of improving the 3D printing technology in coming days.
Accessories to Extruder
There are a couple of accessories that can be used with the extruder for enhanced functionality.
The extruder hot end and nozzle can get VERY hot during printing and continuous printing means the nozzle is getting exposed to higher temperatures which might not be really required and might harm the function of the nozzle. A cooling fan fitted facing the nozzle ensures that only required temperature is attained and maintained. Also it helps the extruded filament material cool and solidifies faster.
A thermostat by function provides a cut-off signal to the heating functionality of a system when the set higher temperature is achieved. A thermostat installed in the nozzle end of the 3D printer ensures that the energy is not wasted in unnecessary heating of the filament material and also ensures safety by not letting the heating go more than the safety set temperature.
Ultimately, you might come across few more advanced features in extruders in latest printers such as detachable extruder, Wi-Fi enabled, Self leveling, etc., but essentially the basics explained in this article will remain same. Keep in mind the above parameters while going through descriptions of the 3D printer extruders.