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What is additive manufacturing?
3D printing - also referred to as additive manufacturing - has enabled the manufacturing of complex geometries to the final shape without need for additional specialized tools, devices, or jigs. The cycle starts with designing the part or assembly in a 3D CAD, or three-dimensional computer-aided design, software. The part is then converted into a triangular mesh that defines its interior and exterior surfaces, commonly known as an STL file. The STL file is then imported into a slicing program that allows the user to manipulate the mesh and define the printing parameters for the process. Slicing is then performed by taking all the user-defined parameters and generating a tool path for each layer of the print. Understanding this workflow is an important factor when designing parts for additive manufacturing because of the different challenges that come with producing a quality part.
Subtractive manufacturing involves material removal with turning, milling, drilling, grinding, cutting, and boring. They start with a larger piece of stock and then remove material until the final part is revealed. Some examples of subtractive manufacturing include laser cutting, waterjet cutting, CNC Machining Centers, Electrical Discharge Machining (EDM), and abrading.
In contrast, additive manufacturing works by joining layers of material sequentially one on the other, to build any unique final form. Whether it's extruding filament through a nozzle, melting metal powder, or curing resin with UV light. There are many different types of additive manufacturing technologies that might not necessarily look alike, but they all create parts by adding material in layers. The most common materials used in additive manufacturing are plastics and metals. The equipment cost is less than subtractive manufacturing, and various material colors are available for most 3D printing operations.
Why choose additive manufacturing?
Additive manufacturing is not a drop-in replacement for any manufacturing process, however a number of different industries such as aircraft, dental restorations, medical implants, and automotive products have turned to additive manufacturing technologies to design prototypes prior to mass production. Additive manufacturing technologies are generally most attractive when there is a need for a fast turnaround from design to finished part, customization of parts, only a small production run or extremely unusual shapes that are not feasible to manufacture with traditional methods.
Additive manufacturing is most useful for those who need the following.
- Parts with complex geometries: because of the way additive manufacturing builds can create parts that would either be expensive or impossible with traditional manufacturing techniques.
- In-house custom parts: additive manufacturing allows you to rapidly go from cad to fully realized parts without the need of a specialized manufacturer. This will enable organizations to easily create iterative prototypes and small-scale manufacturing of custom parts for clients.
- Specific material properties: Because of the unique way that parts are formed, and the variety of materials available allows for control of various material properties such as strength, stiffness, and toughness. Materials and techniques also allow for more specific properties like food-safe, chemically resistant, UV reactive, etc.
Subtypes
Given the vast number of printing technologies available it makes sense to have some sort of system to sort them by. The generally accepted system was created by the international standards organization this systems sorts printers into seven categories based on how they physically print the material
Material Extrusion: general purpose low cost polymer printing
Powder Bed Fusion: small scale metal prototyping/ specialized polymer printing
Vat Polymerization: fine detail resin printing
Direct Energy Deposition: large scale metal printing
Binder Jetting: low energy polymer printing/multi color printing
Material Jetting: high precision polymer prints/ wax casting blanks
Sheet Lamination: rapid production of simple parts