What is FDM 3D Printing? – A Simple Explanation

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FDM (Fused Deposition Modeling) 3D Printing is the most utilized kind of 3D printing. But what is FDM 3D Printing?

Fused Deposition Modelling (FDM) 3D Printing is an additive manufacturing process where melted plastic material is deposited over a build plate line by line and layer by layer until the part is completely printed. The printer follows instructions called “g-code” that tell it where to extrude how much filament at any given time.

Pros and cons of FDM 3D printing:

Additive manufacturing means less wasted materialFDM printing takes a lot of time
Perfect for prototypingNot meant for mass production
Very versatile
Great for hobbyists

A typical 3D printer has a print head that will melt the filament, a motion system that moves the print head in 3 dimensions, a heated print bed where the filament is deposited, and a stepper motor that pushes the filament in and out of the print head.

There are a lot of different kinds of motion systems and print head designs but the main function of a FDM printer is always the same.

In the following, I will explain how an FDM printer works in a little more detail.

The Extruder of an FDM Printer

The extruder is what makes an FDM 3D printer an FDM printer.

An extruder melts the filament and pushes it through the nozzle at the bottom of the extruder. The melted filament is then deposited on the build plate.

An extruder has several parts to it. We will start at the bottom and work our way up.

The Nozzle

The nozzle is located at the very bottom of the extruder. The nozzle can have several sizes but the industry standard is 0.4 mm.

Nozzles can be made out of several heat-transmitting materials such as brass or hardened steel.

The nozzle has a thread at one side that allows it to be screwed into the heat block.

Heat Block

The heat block is the next component of the extruder that we will take a look at. The heat block is made out of metal and it usually has two differently sized holes in it.

One hole is for the heater cartridge and the smaller one is for the thermistor.

The heater cartridge heats up the heat block and the nozzle while the thermistor measures the temperature of the heat block.

This whole assembly that we just talked about is also known as the “hot end”.

Now let’s take a look at the “cold end”.

Heat Break (Heat Sink)

Right above the heat block is the heat break. This part is used to keep the heat from creeping up to the cold end. This part is constantly cooled by a cooling fan.

The filament should only be melted in the hot end. If the filament becomes soft before it arrives in the hot end then the extruder might clog.

Extruder Stepper Motor

Next, we have the extruder motor.

This motor can either be located directly on top of the extruder in a so-called “direct extruder” setup or it can be located on the 3D printer frame and push the filament through some PTFE tubing in a so-called “Bowden” setup.

Both setups have their own pros and cons but in the end, they simply push the filament through the hot end.

Part Cooling Fan

And the final component of the extruder is the part cooling fan.

This fan is often located closer to the hot end but it can also be located above the heat sink cooling fan.

There is often a second part connected directly to the part cooling fan that redirects the air from the fan to the tip of the nozzle.

This whole setup will cool the extruded filament down as soon as it leaves the nozzle.

This is important for overhangs and to ensure that the underlying layers are cool enough so that the next layer has a stable foundation.

Does FDM 3D Printing Require Post-Processing?

FDM 3D printing is a method where a 3D model is printed by applying layers upon layers. This will always result in layer lines being visible on the finished 3D-printed model. So does FDM printing require post-processing?

FDM 3D printed parts donĀ“t usually require any post-processing. But in some instances, some post-processing might become necessary. For example, when printing parts for cosplaying then removing layer lines is probably a must.

There are several ways to smooth 3D prints to remove layer lines such as using acetone on ABS prints or simply sanding the 3D printed part.

If you want to know about smoothing 3D prints then consider reading my guide right here.

What Materials Can be 3D Printed with an FDM Printer?

One of the big advantages of FDM 3D printing is that there are a lot of materials that can be used for printing. So what materials can be used with an FDM printer?

An FDM printer can be used to print a lot of different materials including but not limited to PLA, ABS, ASA, PETG, and many more. There are also materials like TPU that are flexible or glow-in-the-dark filaments. And PLA comes in many different colors including metallic colors and multi-colors.

There are also a lot of filaments that are mixed with glass fiber or carbon fiber to make the filament more rigid.

And more kinds of filaments are being developed every day, it seems like.

The most commonly used type of filament is PLA as it is very easy to print and any commercial 3D printer can print PLA.

ABS and ASA are a little more difficult to print as it requires an enclosure to print reliably. ABS is often used for functional parts as it has a higher temperature resistance and is generally more rigid than PLA.

Hi, I am a passionate maker and professional prop maker for the entertainment industry. I use my woodworking, programming, electronics, and illustration know-how to create interactive props and puzzles for Escape Games and marketing agencies. And I share my knowledge and my experience on this blog with you so that you can become a maker yourself.

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