| 3D printing, also known as additive manufacturing (AM), refers to processes used to synthesize a three-dimensional object from successive layers of material. These objects can be of almost any shape or geometry, and are produced from a 3D model or other data source. |
| 3D printing starts with making a virtual design of the object you want to create. This virtual design is made in a CAD file using a 3D modeling program or with the use of a 3D scanner (to copy an existing object). A 3D scanner then makes a 3D digital copy of an object.
Not all 3D printers use the same technology, although all are additive. Selective laser sintering (SLS) and fused deposition modeling (FDM) are the most common technologies.
Printing:
Before printing a 3D model from an STL file, it must first be examined for errors. In fact, most of the CAD software produced errors in the STL files: holes, faces normals, self-intersections, noise shells or manifold errors. This step is called "repair", as the original model needs to be fixed. Generally STLs that have been produced from a model obtained through 3D scanning often have more of these errors. This is due to how 3D scanning works : as it's often point to point acquisition, reconstruction will include errors in most cases.
Once completed, the STL file needs to be processed by a piece of software called a "slicer," which converts the model into a series of thin layers and produces a G-code file containing instructions tailored to a specific type of 3D printer (FDM printers). This G-code file can then be printed with 3D printing client software (which loads the G-code, and uses it to instruct the 3D printer during the 3D printing process).
Printer resolution describes layer thickness and X-Y resolution in dots per inch (dpi) or micrometers (µm). Typical layer thickness is around 100 µm (250 DPI), although some machines can print layers as thin as 16 µm (1,600 DPI). X-Y resolution is comparable to that of laser printers. The particles (3D dots) are around 50 to 100 µm (510 to 250 DPI) in diameter.
Construction of a model with contemporary methods can take anywhere from several hours to several days, depending on the method used and the size and complexity of the model. Additive systems can typically reduce this time to a few hours, although it varies widely depending on the type of machine used and the size and number of models being produced simultaneously.
Traditional techniques like injection moulding can be less expensive for manufacturing polymer products in high quantities, but additive manufacturing can be faster, more flexible and less expensive when producing relatively small quantities of parts. 3D printers give designers and concept development teams the ability to produce parts and concept models using a desktop size printer.
Finishing:
Though the printer-produced resolution is sufficient for many applications, printing a slightly oversized version of the desired object in standard resolution and then removing material[31] with a higher-resolution subtractive process can achieve greater precision.
Some printable polymers such as ABS, allow the surface finish to be smoothed and improved using chemical vapor processes.
Some additive manufacturing techniques are capable of using multiple materials in the course of constructing parts. These techniques are able to print in multiple colors and color combinations simultaneously, and would not necessarily require painting.
Some printing techniques require internal supports to be built for overhanging features during construction. These supports must be mechanically removed or dissolved upon completion of the print.
All of the commercialized metal 3D printers involve cutting the metal component off the metal substrate after deposition. A new process for the GMAW 3D printing allows for substrate surface modifications to remove aluminum or steel.
Key vendors: 3D Systems, Stratasys, Voxel8 |
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