FDM 3D printing is a process known as Fused Deposition Modeling (FDM) or Fused Filament Fabrication (FFF), Basically, FDM involves feeding strands of plastic material into a hot metal block with a nozzle. The filament melts and the movement of the printer deposits it into the desired shape.
Therefore, the extrusion mechanism part of the feeding extrusion has become the key to determining whether the model can be successfully formed. Today, we will briefly understand what the 3D printing extrusion mechanism includes, and what are the differences between them and their benefits.
Then What is an extrusion mechanism? The extrusion mechanism of a 3D printer is a set of components that move and process filament. Its structure can be split into the cold end and hot end. Please refer to the following figure for the specific structure.
3D Printer Extrusion Mechanism Classification
The extrusion mechanism is generally classified as "proximal extrusion mechanism/Direct Drive Extruder" and "distal extrusion mechanism/Bowden Extruder".
The proximal extrusion mechanism, also known as direct drive, refers to the direct connection between the "cold end" (extrusion part of the filament) and the "hot end". The advantage is that it can better control the movement of filament and print flexible filament such as TPU.
Distal Extrusion, also known as Bowden Extruder, means that the "cold end" and "hot end" are separate, usually connected by Teflon tubing. The advantage is that the print head is lighter and prints fewer streaks. Here is the picture so you can better identify their differences.
Then what do we usually mean by MK6, MK8, MK10, and V6?
I believe that when it comes to extrusion mechanism, you will often see the terms MK6, MK8, MK10, and V6, they are actually a series of the hot end, extruder, and nozzle combinations together to be a whole system, allowing the filament going through the nozzle from the 3d printer, which we call it as an extrusion system.
MK is the abbreviation of Mark, which represents the version number. The MK6, MK8, MK10 (by Makerbot), and V6 (by E3D) are a range of extrusion systems that combine hot ends, extruders, and nozzles.
The MK6 is the first commercial hot end to be sold as a complete kit rather than individually. It has a stainless steel heating block, while the MK6+ upgrade kit has an aluminum block with a different design, making it smaller and lighter. MK6 nozzles have M6 thread size, which means thread diameters up to 6mm. (MK6 is now basically eliminated)
MK8 nozzles also use M6 thread sizes. This means that MK8 nozzles can be used with MK6 extruders and vice versa. One of the differences between the MK8 hot end and the V6 hot end is the length. The overall length of the V6 is shorter than the MK8, but the thread is longer. If you're changing from an MK8 to a V6 nozzle, you may need to move the Z-End-stop switch up a bit so you can still level your bed.
The MK10 uses M7 threads instead of the M6 threads used by all previous models. The main reason for this is that the 4mm PTFE liner doesn't have enough metal to make the outer tube with the M6 thread. You will not be able to use the MK10 series with any other previous hot-end models as they have different-sized threads.
Common cold junction types
MK8 Extrusion - Simple, get the job done, low price range type extrusion system, like what we used on our first Tycoon version 3d printers (most entry-level printers use this):
Titan Aero-The same goes for E3D's Titan extruder - it doesn't have a dual gear feed, but does use a 3:1 gear ratio and is meant to be a lightweight, drop-in extruder.
There is a choice of extrusion gears (left) or a full set of extruders (right)
Bontech BMG - mid-range product and willing to spend a little more
1. Double gears, stronger pulling force, fast retraction, no damage to filament;
2. Durable, printing complex models can be pulled back many times without wear;
3. Adjustable tension;
4. One-key quick discharge and material change.
For 3D printer enthusiasts who are very proud of their 3D printing quality and pursue the top range E3D Hemera:
Featuring a unique heat sink design and compact frame, E3D's Hemera dual gear extruder is a miniature power unit capable of applying up to 10kg of thrust to the filament. It does this using a 73:22 gear ratio, which provides incredible grip for such a small extruder.
Compatible with the company's hot-end ecosystem, including the V6 and Volcano series, the Hemera is the successor to E3D's popular Titan extruder. The Hemera can be configured as a direct extruder and a Bowden extruder, available in 12V and 24V models, and compatible with 1.75mm filament.
Common Hot End Types
4.1 Hot end structure: cooling block + heat insulation device + heating block + nozzle, and heat break
4.2 Classification of the hot end: PTFE/PEEK hot end and all-metal hot end, the difference lies in the material of the thermal insulation device.
Traditionally, the hot end has used PEEK (polyetheretherketone) as an insulator for PFTE (polytetrafluoroethylene) tubing within the insulation, guiding the filament into the heating block for melting.
In the days of simply printing PLA or ABS - often requiring low temperatures to print - PEEK was sufficient. However, attempting to print tougher and more demanding filaments requires higher temperatures (above 260°C), which can damage PEEK and PTFE, release toxic fumes, destroy prints, and generally make your hot end Make a mess and endanger your health.
All metal hot ends were introduced at this time to print materials that require higher temperatures. We now often see stainless steel thermal disconnects in place of PEEK insulators separating the PTFE tubing from the cold end from our heating blocks.
Common hot ends
1.The most common kind is the MK8, MK10,V8 like what mentioned previously.
2. The other kind is mosquito, which you might heard a lot - Mosquito (designed by Slice Engineering)
1. Excellent heating performance
2. Special material, structure, and stability
3. Larger temperature working range, up to 550℃
4. Modular, suitable for almost all FFF/FDM printers
5. Ideal for multi-extrusion systems
7. The nozzle can be changed with one hand.
There are also some components that affect the quality of extrusion: nozzles, motors, fans, etc. The parameters and structures are relatively simple, and you can explore them by yourself. This PPT mainly discusses the cold-end and hot-end structural parts.