The extruder is the most important piece of equipment in a 3D printer.
FDM printers create models by layering filaments one layer at a time. The extruder is the tool that moves, heats, and extrudes the filament out of the printer. The type of extruder and print head used will affect the quality and style of the print. For this reason, it is considered an essential component of a 3D printer.
In this article, we will discuss the basic information you need to know about extruders and print heads in 3D printers.
What is an extruder for a 3D printer?
The extruder is the part of the 3D printer responsible for extruding the filament, melting it, and placing it on the bed to create the model. 3D printer extruders consist of multiple tools that serve different tasks. These are the cold end and the hot end.
The parts of the 3D printer that move, melt, and deposit the filament are called the cold end and hot end assembly. We may also simply refer to the part that moves the filament as the extruder and the part that melts it as the hot end.
The cold end is responsible for moving the filament to the hot end. A motor and gears work to move the filament through the PTFE TEFLON tubing (PolyTetraFluoroEthylene) or directly to the hot end. There are two types of cold ends with slightly different mechanisms, which will be discussed in the next chapter.
The hot end heats the material, melts it, and extrudes it layer by layer through a nozzle. The two main components of a hot end are
A “heater” that heats and melts the filament. The nozzle directs the filament as it is extruded.
Types of Extruders for 3D Printers
There are two main types of extruders for commercial 3D printers: direct and Boden. Some types of 3D printers are also equipped with double extruders; let’s take a look at the differences between the three.
In a direct extruder, the filament passes from the gear to the cold end and then to the hot end, all at once. In other words, the drive and gears that move the filament are mounted directly above the hot end.
Because the extruder is directly above the oven, it is heavier and slower. However, many people prefer to print flexible 3D filament using a direct extruder. Direct extruders allow the filament to travel a shorter distance before melting and settling. Therefore, problems are less likely to occur during the extrusion process.
In a Bowden extruder, the cold end and hot end are separated by a PTFE tube through which the filament passes. Instead of placing the cold end directly on top of the hot end, the tubing separates the two parts.
Unlike direct extruders, Bowden extruders are extremely lightweight and fast because the only moving part is the hot end. The cold end, which has a drive unit, is positioned in a fixed position on the printer.
Bowden extruders can print high-quality patterns and are suitable for printing long, continuous patterns. It was once said that soft materials could not be used with Borden extruders, but that idea is now outdated. There are no gaps for filaments to move or twist, allowing them to move smoothly through the tube to the heating block.
In addition to various styles of extruders, some printers can be equipped with two or more extruders.
Dual extruders allow you to print more than one material at a time or two models simultaneously. Dual extrusion speeds up the printing process because there are two tools to move, melt, and deposit the filament.
Dual extrusion can also be equipped with an independent dual extrusion system (IDEX). This means that each extruder operates independently. So while a typical dual extruder can run simultaneously, each IDEX extruder runs independently. This results in higher efficiency, increased productivity, and potential time savings.
One cannot talk about extruders without mentioning hot ends. As mentioned above, the hot end is the part of the extruder that is responsible for melting the filament and pushing it onto the bed.
Depending on the nozzle installed, the hot end can be customized. Since the filament is extruded through nozzles, the size and type of nozzle you choose can have a significant impact on the style and effect of your model.
3D printers are equipped with a wide variety of nozzles, depending on the type of material and design to be printed. This subject is so vast that we could spend an entire article on it.
If you are having trouble
If you are having problems with these printer components, it is most likely due to “insufficient extrusion,” the most common printing problem with 3D printers. This problem is caused by inadequate extrusion of material into the printed part and manifests itself in the form of insufficient filament extrusion, missing layers, and spongy prints. Insufficient extrusion can be caused by
- Older software
- Wrong material selection
- Bowden tube condition
- Insufficient capacity
- Hot end problems
- Extruder board problem
- The extruder motor does not push the filament correctly.
The next time you look at a 3D printer, you’ll appreciate a little more all the work that goes on inside the little device called an extruder, and like many other aspects of 3D printing, understanding this tool and how it works will help you become a more efficient user and improve the quality and features of your prints.