Fused deposition modeling, or FDM 3D Printing, is a method of additive manufacturing where layers of materials are fused together in a pattern to create an object. The material is usually melted just past its glass transition temperature, and then extruded in a pattern next to or on top of previous extrusions, creating an object layer by layer.
In layman’s terms, a typical FDM 3D printer takes a plastic filament and squeezes it through a hot end, melting it and then depositing it in layers on the print bed. These layers are fused together, building up throughout the print, and eventually they will form the finished part.
FDM is the same as fused filament fabrication (FFF), but the term “fused deposition modeling” and the abbreviated “FDM” were trademarked by Stratasys in 1991, creating the need for a second name.
Many types of materials can be used with FDM techniques, including the most common thermoplastics, chocolate, pastes, and even “exotic” materials like metal- or wood-infused thermoplastic.
Widely accepted as the simplest way to achieve 3D printing, FDM is cheap and fairly efficient. FDM 3D printers dominate the 3D printing market, almost drowning out more expensive methods. For a list of all 10 methods of 3D printing, take a look at this article, and to find the best 3D printers available today, have a look at this curated list.
Variations in Design and Capability To top
A diagram of Cartesian and delta designs. Source: SciELO
Variations in the extrusion system of fused deposition modeling 3D printers include, but are not limited to:
Filament extruders, the most common and versatile variation which utilizes reels of thermoplastic filament
Pellet extruders, exchanging the filament for granules of plastic
Chocolate extruders (whoopee!)
Paste extruders, where any paste can be extruded. Common uses are with ceramics and food. Paste extrusion is sometimes left in its own category, as the paste is not necessarily a thermoplastic material.
The common theme with all of these variations is that a substance is being extruded through a nozzle onto a build plate and/or fusing through heat or material adhesion to a previous layer in specific patterns to create a shape, which is the basis of an FDM 3D printer.
Other variations in FDM 3D printing include the systems of movement for all 3 axes on a printer. The two main variations are Cartesian 3D printers — like the RepRap/Prusa i3 or the CoreXY designs — and delta 3D printers. Each has advantages over the others, but they all use the same general method of printing.
Advantages and DisadvantagesTo top
A simple part printed using various methods. Source: 3D Hubs
FDM offers a number of advantages over other 3D printing methods, but it also has some downsides.
Pros
One of the biggest advantages of FDM 3D printing is scalability: It can be easily scaled to any size. This is because the only constraint in the size of a build area is the movement of each gantry – make the gantry rails longer and the build area can be made larger. Of course, there are a few minor issues, and at a certain point the cost is no longer offset by the benefits, but no other printer design is capable of being scaled as easily with as few issues as FDM.
One of the more obvious benefits of having an easily-scalable design is the cost-to-size ratio. FDM printers are continually being made bigger and less expensive, due to low part costs and the simple designs involved. Other styles of printer cost many times more per unit area of build volume, simply because they are difficult to scale up and the key components are still quite expensive.
Another advantage is material flexibility. On any FDM printer, a wide variety of thermoplastic materials and exotic filaments can be printed with relatively few upgrades and modifications, something that cannot be said of other styles where a material must be a resin or fine powder.
Cons
3D Printing has become a household term in recent years but, the process, also known as Additive Manufacturing, has been around since the 1980s. Originally referred to as Rapid Prototyping, the process was conceived to produce prototypes quickly, with minimal tooling and effort. In recent years, the technology has expanded beyond prototyping and has become sufficiently advanced to enable its use for manufacturing at production quantity levels, particularly in specialized and small to medium-scale applications.
As with any additive manufacturing technology, a computer-aided design (CAD) file is required. The additive manufacturing machine processes the file (assuming proper compatibility) and then constructs the model layer-by-layer. There are a growing number of techniques/technologies available to create a 3D-printed object. In this article, we will provide an overview of the common types of 3D printing technology, organized around the underlying process that defines their operation.
The terms 3D Printing and Additive Manufacturing will be used synonymously.
Material Extrusion Processes
A material extrusion process is one in which a thermoplastic material is fed into a heated nozzle which melts the plastic and allows it to be deposited onto a build platform – a flat surface used to hold the 3D printed part. Each layer of the design is deposited sequentially until the entire part isbuilt. The most common 3D printing technologies that use the material extrusion process are Fused Deposition Modeling (FDM™), and Fused Filament Fabrication (FFF).
Fused Deposition Modeling (FDM) and Fused Filament Fabrication (FFF)
The most widely used additive manufacturing process is Fused Deposition Modelling 3D Printing (FDM), a material extrusion technology in which molten thermoplastics are deposited layer by layer to create the desired form. Typical materials include Polylactic Acid (PLA) as well as engineering-grade plastics such as Acrylonitrile Butadiene Styrene (ABS), Polycarbonate (PC), Polyetherimide (PEI), among others.
FDM is the most common method used in home desktop printer models, but typically requires more user upkeep and maintenance compared to their industrial counterparts. One common home 3D printing technology similar to FDM is Fused Filament Fabrication (FFF) , which also uses continuous filaments of thermoplastics, such as PLA, that are heated and extruded through a nozzle onto a build platform. Filaments are available in various colors and materials, sold on spools.
In industrial settings, FDM is used to create both prototype and end-use parts. However, raw parts produced with this technique often have visible layer lines, requiring additional processing and finishing. Additionally, some designs require support structures to fabricate overhangs.
Vat Photopolymerization Process
Stereolithography (SLA)
