FDM/FFF Printing Explained

FDM 3D printing, also known as Fused Filament Fabrication (FFF), is probably the most widely recognised method of 3D printing technology that builds objects layer by layer using melted plastic from a spool of filament.  Available machines range from relatively basic and low cost hobby machines, to industrial specification able to print specialist plastics and large format items.

Materials:

FDM printers use spools of thin plastic filament.  The most common materials are typically thermoplastics like ABS, PLA, PETg and ASA, but there are a vast array of materials and colours available.

The Printing Process:

1. Feeding the Filament: The filament is loaded into the printer and feeds through a tube to a heated nozzle in the print head.
2. Melting the Plastic: Inside the nozzle, the filament is heated to a specific temperature, melting it into a liquid plastic.
3. Depositing the Material: The molten plastic is pushed out of a tiny nozzle onto a build platform. The printer head moves horizontally following a digital design file (usually a sliced STL file) which instructs it on where to deposit the material.
4. Building layer-by-layer: As each layer cools and solidifies, another layer is deposited on top, slowly building up the 3D object.
5. Support Structures: For objects with overhangs or complex geometries, support structures are often printed alongside the main object. These temporary structures provide support and prevent the molten plastic from drooping or sagging. After printing, the support structures are removed manually.

The Advantages of FDM Printing:

• FDM is a versatile and affordable 3D printing technology.
• Wide variety of materials available with different properties for various applications.
• Relatively simple process compared to other 3D printing methods.

The Disadvantages of FDM Printing:

• Surface Finish: FDM printing builds objects layer by layer, resulting in visible layer lines on the final product. This can be a drawback for applications requiring a smooth surface finish. While post-processing techniques like sanding and vapor smoothing can improve the finish, they add extra time and effort.
• Limited Detail: The nozzle size in FDM printers limits the level of detail achievable. While details can be quite good, they won't be as sharp or intricate as what you can achieve with technologies like SLA that use lasers for higher precision.
• Strength Anisotropy: FDM printed parts tend to be stronger in one direction (along the layer lines) compared to another. This can make them more susceptible to breaking under certain forces.
• Warping and Delamination: Uneven cooling during printing can cause warping or curling of the filament, especially with larger prints. Additionally, improper temperature settings can lead to delamination, where layers separate and weaken the part.
• Support Structures: For objects with overhangs or complex shapes, support structures are necessary to prevent drooping. These supports require additional printing time and need to be removed afterwards, which can be tedious for complex prints.
• Limited Colour Printing: While there's a good range of filament colours available, FDM printing typically produces single-color objects or objects with a limited number of solid colours.

Overall, FDM printing is a great choice for many applications, but understanding its limitations helps you decide if it's the right method for your project. If you need high detail, smooth finishes, or strong parts in all directions, you might want to consider other 3D printing technologies such as SLA or MJF