At this point manufacturers are familiar with the major differences between Additive and Subtractive processes. Most of us have likely even dabbled in 3D printing even if just to make a fun, little trinket with an extruder and plastic filament. While enjoyable, it is sometimes difficult to imagine this same technology being applicable in a modern machine environment. After all, that’s where sparks fly, right? How can this “glorified hot glue gun” really work on a shop floor?
The answer to that second question is not well for most applications, even if some manufacturing processes have thrived on the rapid prototyping of quick-to-make but easy–to-break plastics. In this article, we’ll give a quick rundown of the types of Additive Manufacturing techniques, which are generally split between those for plastic and those for metal. Then, we will expand on four of the methods that are most useful for production processes. Perhaps you will even find one worthy of implementation into your own process.
Additive Processes for Plastic Part Manufacturing:
Making plastic parts using an additive process isn’t just limited to the extruder based printers mentioned earlier. While extruders may be the most common and easiest to use, there are two other plastic Additive Manufacturing techniques worth consideration for the right application:
Stereolithography (SLA):
Chances are if someone has a desktop 3D printer that does not use an extruder they are using an SLA printer. With this technique, liquid plastic is cured into a solid part layer by layer and the part is pulled out of the liquid as it builds. While you would generally use SLA for the same applications as an extruder based printer, SLA is much faster and a better fit for manufacturers concerned with creating a smoother surface finish and quick build times.
Jetting
Whether curing the build material or adding a binding agent to powder, all types of jetting involve solidifying a combination of materials layer by layer to form a complete part. Jetting generally produces higher quality parts than other plastic methods and can be built with color and other unique properties. One example is the production of organ models which surgeons use for study and practice. Better yet, because this process uses a combination of materials that form during a chemical reaction it can be used to create different textures (like spongy and flexible) to better differentiate portions of your build.
Additive Processes for Metal Part Manufacturing:
While SLA and jetting produce relatively strong and sophisticated plastic parts, even these methods cannot yet meet the needs that can only be filled by the metallic parts on which manufacturers have relied. When a manufacturer’s need focuses on the material properties of the tougher alloys used in industries like aerospace and automotive, that leaves two major methods of metal Additive Manufacturing:
Direct Metal Laser Sintering (DMLS)
DMLS can be considered similar if not the same as the other sintering and melting processes (EBM, SHS, SLM, SLS) which can all be considered powder bed processes. In DMLS, layers of powder are melted by a laser, layer by layer, until the part is finished. The limitations of this method are largely dependent on the application of the powder and the dimensions of the build space. However, DMLS excels at forming complex geometries. If a part requires a path that a tool cannot reach through the subtractive process, or the part is so intricate that it would take a machinist weeks to make, DMLS makes that design possible with the added bonus of a much quicker turnaround.
Direct Energy Deposition (DED)
The DED process is most often used in powder nozzle machines. Rather than a laser meeting the powder, the DED method makes the powder meet the laser. In this process a pressurized stream melts the powder and creates layers. Surface finish is generally unfinished compared to DMLS. However, parts made using DED have the added advantage of being able to be added on to pre-existing parts. This makes extra features and repairs much more viable.
There are other additive methods out there (like an extrusion method that uses metal wire filament), but they fall within similar properties of those previously mentioned or are not yet at a realistic technological readiness level for successful implementation into a production process. Knowing the right advantages and limitations of implementing additive technology is the difference between being able to actively leverage production-quality parts versus a potentially expensive machine that only produces trinkets. Hopefully this information has given you a basis to further explore the possibilities in Additive Manufacturing and whether or not this emerging technology is right for you.
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