Fused deposition modeling™ (FDM®) is a computerized manufacturing process for making three-dimensional parts. The equipment creates parts in detail by layering a meltable thermoplastic repeatedly to form the desired shape. Deposition modeling can create plastic parts for testing without making intermediate parts from clay or resins. The process is also useful for building specialty or low-volume parts without having to create tooling or molds, saving time and expense.
A computer drawing of the part or shape is made, and software separates the image into very small slices. This file is entered into the fused deposition modeling™ equipment, which uses the software to drive a nozzle head. Meltable plastic is continuously fed to the nozzle, which heats the plastic just to its melting point. The softened plastic is placed on a tray inside the modeling equipment as a series of very small dots that harden quickly.
The nozzle reacts to the computer program by moving in two dimensions, called the X- and Y-axis. Continuously fed plastic is placed according to the software on points that match the software's slice of the product. Once a slice is completed, the nozzle moves vertically by a very small amount, and the next slice is deposited. This process continues until the part is fully fabricated.
Different processes can build parts using deposition modeling techniques. Stereolithography uses a laser and a light-sensitive resin to build parts. Resin parts may not have the same structural strength as parts made from fused deposition modeling™, but are useful as prototypes. Metal parts can be fabricated using direct metal laser sintering, which melts fine metal powder in layers with a high-power laser.
A variety of thermoplastic resins are available for fused deposition modeling™. Acrylonitrile butadiene styrene (ABS) is commonly used due to its thermal properties, low cost and strength of the finished parts. Other thermoplastics that can be used in FDM® include polycarbonates, polycaprolactones, and polyphenylsulfones. The choice of plastic depends on whether strength, high temperature resistance, or a combination of both is needed for the finished part.
Fused deposition modeling™ and other deposition processes are sometimes referred to as instant parts. This is not really the case, since the materials must be deposited in very fine layers repeatedly to build a part. Forming a part or shape can take hours or even days depending on the complexity of the design. The advantage of using FDM® technology is that a single piece can be produced directly from a computer drawing. Design changes can be made easily, and another piece can be produced immediately from the drawing.