2.1. Process and Working Principle

FDM is a material extrusion process where a thermoplastic filament is fed from a spool into a heated extrusion nozzle.

Fused Deposition Modeling (FDM) is a method used in 3D printing. It involves taking a specialized plastic filament (a flexible plastic string) from a spool and feeding it into a nozzle that heats it to a melting point. As the melted plastic comes out of the nozzle, it can be shaped directly onto a flat surface, layer by layer, to create a three-dimensional object.

Think of FDM like squeezing frosting from a tube to decorate a cake. As you squeeze the frosting, it comes out in a hot, flowy form. When it makes contact with the cooler cake surface, it starts to set and harden. Similarly, in FDM, heated plastic is layered to build up and form the desired shape.

The nozzle melts the filament and deposits it layer by layer onto a build platform following a prescribed path from CAD-generated G-code.

In FDM, once the nozzle is ready and the filament is melted, the printing process begins. The machine follows a path that has been pre-determined using computer-aided design (CAD) software. It creates a set of instructions, called G-code, which dictate exactly where the nozzle should move to deposit each layer of melted material. This process continues layer by layer, gradually building up the entire object.

Imagine a printer that uses a paintbrush instead of ink to create a picture. Each stroke is a layer of paint that adds to the image. Like painting in layers, FDM builds up layers of plastic to create a complete 3D object.

The extruded material cools and solidifies, fusing with previous layers to form the 3D component.

After each layer of plastic is deposited, it cools down and solidifies quickly, bonding with the layer beneath it. This cooling process is essential because it allows each layer to adhere to the previous layer without the risk of falling apart. Each solid layer creates a strong foundation for the next, leading to a sturdy final product.

Consider what happens when you build a snowman. Each snowball you add needs to be compact and firm so that it sticks to the one before it. Just like snow that holds together, quite as important is the melting plastic quickly becoming solid for stability in 3D prints.

The print head moves in three axes (X, Y, Z) to build complex geometries.

As the printer moves, the print head can shift along three different directions: left to right (X-axis), forward and backward (Y-axis), and up and down (Z-axis). This three-dimensional movement allows the printer to create intricate designs and shapes, making it a versatile tool for various applications.

Think of it like a robotic arm that can reach in multiple directions to build a sculpture. Just as the arm moves all around to place pieces of material exactly where they are needed, the print head does the same thing to create detailed 3D shapes.

Typical thermoplastics: ABS, PLA, PETG, Nylon, TPU, PEI. Composite or enhanced filaments: carbon-fiber reinforced, graphene-doped PLA.

FDM utilizes various materials known as thermoplastics, which become moldable above a specific temperature. Common materials include ABS (common in many toys), PLA (a biodegradable option), PETG (strong and durable), and others like Nylon or TPU (for flexibility). There's also the possibility to use composite materials, which have special properties, such as enhanced strength due to carbon fiber reinforcement.

Think of thermoplastics like different types of dough used for baking. Each type of dough has unique properties; some are strong and suited for cookies (like ABS), while others can be rolled thin for delicate pastries (like PLA). Depending on what you need to create, you choose the type of dough (material) that best suits your recipe.

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