Fused Deposition Modeling (FDM) & 3d printing

Fused Deposition Modeling (FDM) is an additive manufacturing process for the cost-effective production of prototypes, mainly from plastics such as ABS, PEI or PC. The basis of FDM 3D printing technology is the so-called filament. These are plastic fibers that are rolled up on a roll. During the FDM process, this filament is printed through a nozzle, also called an extruder. The filament is then melted inside the extruder, allowing this thin strip of material to be deposited on a build platform. Once the extruder has successfully extruded a layer of filament, the build platform lowers by one layer thickness and a new layer of filament can be applied. This process repeats until the desired object is completed.

The beginnings of FDM 3D printing date back to the late 1980s. At that time, American, Scott Crump, made his first attempts with a mixture of wax and plastic. He extruded the mixture from a hot glue gun to make a toy for his daughter. The toy didn’t particularly live up to that designation, but Crump recognized the potential behind the method and began working on automating it. He mounted the hot glue gun on an apparatus that could move in all three directional dimensions – X, Y, and Z. In 1989, he filed the first patent for this technology, which would later become known around the world as fused deposition modeling. Shortly after his patent was granted, he founded Stratasys, which remains one of the world’s leading additive manufacturing and FDM 3D printing services.

The biggest advantages of FDM 3D printing are the simplicity of the process and the low-cost materials. Processing plastics using an extruder is relatively easy to set up compared to laser or UV light-based process technologies. As a result, FDM 3D printers are significantly less expensive than alternative additive manufacturing technologies. They are also widely used at home as desktop printers, as neither lasers nor chemicals are required to cure the components. The material portfolio for the FDM process offers a wide selection of different filament plastics such as polylactide (PLA), acrylonitrile butadiene styrene (ABS), polycarbonates (PC), and polyphenylsulfone (PPSF).

In the four decades since the manufacturing process of FDM was invented, these materials have evolved, as has the process technology itself. As a result, the inexpensively available filaments are already optimized for 3D printing. Unlike other 3D printing technologies, the FDM process can be interrupted during printing to incorporate other materials, such as metals, into the part.

The most common materials for this type of 3D printing technique are various plastics – from solid, stable plastics such as ABS or PLA to flexible materials such as TPE. In addition to plastics, metals, ceramics, and resins can also be printed using an FDM printer. In the construction industry, an FDM-based process is increasingly establishing itself, in which concrete is printed using an extruder. This allows entire houses to be 3D printed in just a few days. In addition, the FDM printing machines can also be used to process wax and 3D print models for metal investment casting. In more experimental studies, foodstuffs through to organic tissue material have also already been printed using fused deposition modeling technology.

Cartesian printers are among the most common variants of FDM 3D printers. In these printers, the X-, Y- and Z-axes are each controlled by their own motor. Usually, in such models, the Y-axis is mapped using a movable build platform. The X-axis corresponds to a carriage to which the extruder head is attached, and the Z-axis is controlled by toothed belts or threaded spindles. These Cartesian models are particularly easy to set up and maintain, but can become imprecise at higher heights.

Another variant is a special form of Cartesian printer. So-called CoreXY printers have the extruder positioned in X and Y via two axes instead of a moving build platform. This allows the printing speed to be increased while reducing vibrations.

A final variant worth mentioning are delta FDM printers. In these, the extruder is controlled by three vertical tie bars that move via a rail or toothed belt system. The extruder hangs freely above the static build platform and builds the components in a virtual cylindrical build space. With this printer variant, very large build spaces can be filled at high speed and with high precision.

When comparing fused deposition modeling to voxeljet’s Binder Jetting technology, it is important to look at the applications, volumes, and processing times associated with each technology. voxeljet’s Binder Jetting processes is better suited for large scale industrial applications. This is because it can produce large volumes of complex parts with extreme accuracy. Comparably, FDM is especially suited for at-home recreational use since the printing beds are small and it is hard to produce complex parts with accuracy, although there are some industrial FDM printers. The build volume for FDM printers is up to 300 x 300 x 600 mm whereas voxeljet’s VX4000 printer for sand is 4 x 2 x 1 meters with a print volume of up to 111 liters per hour. Both technologies also focus on different materials. FDM prints mostly from plastics, whereas Binder Jetting utilizes a wide range of materials from sand and ceramics to plastic. On a large scale, Binder Jetting has a much faster processing time and lower cost per part. Binder Jetting is commonly used in metal casting where the molds and models are turned into prototypes and end use parts. An emerging variant of Binder Jetting is the printing of metal parts for end use applications. FDM, on the other hand, plays a larger role in product development and prototypes, as well as prosthetics and other smaller applications. Conclusively, FDM is best for small-scale prototyping and modelling whereas voxeljet’s 3D printing technology is best for large-scale prototyping and industrial use.