3D Printing Machines for Metals – Types and Applications

Although plastics are the most common 3D Mapping printing materials, metals can be used to create parts with superior dimensional accuracy and premium surface finish. Parts can also be created using tailored materials to deliver specific physical properties such as heat resistance or higher strength.

FDM 3D printers extrude solid thermoplastics, such as Acrylonitrile Butadiene Styrene (ABS) and Polylactic Acid (PLA), through a heated nozzle layer by layer onto a build platform. It is a fast, affordable and versatile method for prototyping.

Fused Deposition Modeling (FDM)

Fused deposition modeling builds the structure of 3D-printed objects by advancing a molten plastic thread through a computer-controlled extrusion head. This is the most popular and affordable desktop printing technology, making it the standard for rapid prototyping.

CAD software converts digital models into G-code, which the printer executes through a gantry system that moves the extruder nozzle over a build platform to create layers of plastic material. After completing one layer, the platform lowers and the nozzle deposits another melted track directly on top of the previous one, repeating the process until the model is complete.

Larger industrial FDM systems typically feature two extruding nozzles on linear slides and support for multiple plastic filament spools. The first extruder prints the “model” of the 3D part, while the other prints the external support structures that help the finished product maintain its shape. The model and support extruders can use the same material or different materials. Hobbyist systems often only have one extruder.

Various plastics, such as PLA (polylactic acid) and ABS (acrylonitrile butadiene styrene), along with composites like wood, are available to make custom FDM parts. This flexibility makes it easy to prototype designs, test fit and functionality, or produce small batches of components. However, FDM printing is limited in its ability to withstand high loads and stresses and produces parts with visible layer lines that might require post-processing techniques such as sanding, tumbling, or vapor smoothing.

Stereolithography (SLA)

The SLA process uses liquid photopolymer resins to construct 3D printing company models. The resins are exposed to ultraviolet laser light, which solidifies or cures them layer by layer. As the laser beam traces over the surface of the print area, a wiper blade or recoating system spreads the next layer of liquid resin on top.

The precision and smooth surface finish of SLA prints make them ideal for medical and dental applications, jewelry design, and sculpting. The process can also create patterns or molds for investment casting, injection molding, or other manufacturing processes.

Inventor Hideo Kodama developed the first machine that leveraged UV light for curing photopolymers in 1981. Chuck Hull built upon this invention and filed a patent for stereolithography in 1984. He later founded 3D Systems in 1987.

A SLA printer consists of a tank or vat filled with liquid photopolymer resin, a build platform, and a control system that is used to monitor and direct the UV laser and recoating system. A computer, software, and actuators control the position of the laser beam and build platform.

The closed, heated build environment and precise tolerances of SLA printing produce incredibly accurate parts that are a step above standard machining accuracy. This accuracy is a result of the lower printing temperature compared to thermoplastic-based technologies, which minimizes thermal expansion and contraction effects that cause parts to warp or crack.

Selective Laser Sintering (SLS)

SLS uses a laser to selectively fuse layers of powdered material. Unlike FDM printers that dispense heated filament through a nozzle, SLS machines use a laser beam to sinter the powder material into solid parts. This makes SLS ideal for producing parts with intricate geometries. In addition, sintering the material in layers instead of extruding it in continuous streams allows SLS to fabricate overhanging designs that would be difficult or impossible using other 3D printing processes.

As a result, SLS parts have superior mechanical properties and can be used as end-use components. SLS parts also have a uniform surface finish with almost no visible layer lines. These characteristics, along with a wide range of established materials—including engineering thermoplastics like nylon 11 and 12—make SLS an ideal choice for functional prototyping or bridge manufacturing.

In addition, SLS uses a powdered build platform to produce parts, making it possible to make extremely large parts. Typically, the powder is spread evenly across the build surface and then heated to a temperature just below its melting point for efficient sintering.

Since the entire part is built in one go, SLS eliminates the need for dedicated support structures. This makes it easier to construct complex geometries, interior features, and undercuts. The only drawback is that the high power density of SLS machines can make them dangerous to operate at home, so most people opt for professional services or purchasing a benchtop machine from companies like Formlabs (machines starting at $24,999). Learn more about SLS and its applications.

Digital Light Processing (DLP)

DLP printers use a light-curing photopolymer to print objects. This technology offers high-level dimensional accuracy and fine element subtleties, but is limited by the speed at which it prints. It’s best suited for producing prototypes, dental applications, and jewelry.

The key component of this 3D printing method is a Digital Micromirror Device (DMD), an image projection system built into the printer. It consists of a matrix of microscopic-sized mirrors that are controlled by a chip and rapidly toggled to direct light at specific coordinates on the build platform’s surface during printing. Most DLP printers build bottom-up and are able to create polymer models up to several tens of centimeters in size.

For DLP printing, the most common type of filament is acrylonitrile butadiene styrene or ABS. However, there are a wide range of specialty filaments that offer unique physical properties, such as wood, ceramic, glow-in-the-dark, or ESD-safe. These filaments typically require more careful maintenance and have different performance specifications than standard materials.

Regardless of the filament type, it’s important to determine how large your final printed object will be and what level of accuracy you need. Most manufacturers will specify a maximum effective build volume, as well as minimum wall/layer thicknesses and minimum printable feature sizes, so you can determine whether the machine meets your needs. Also, be sure to consider the footprint and weight of the machine as well as its operating environment.

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