How 3d printing works
3D printing also known as additive manufacturing is a process of making three dimensional solid objects out of digital files. The creation of a 3D-printed object is gotten using additive processes. In an additive process an object is formed by laying down successive layers of material until the entire object is completely formed. These layers can be seen as very thinly sliced horizontal cross-section of the eventual object that is formed.
HOW DOES 3D PRINTING WORK?
There are various types of 3-D printers. Though different materials could be used, but they all involve the same basic approach for printing an object, spraying or transferring the said substance in multiple of layers to a building surface, by beginning with the bottom layer first. It all starts with making a virtual design of the object you want to make. This virtual design is made in a Computer Aided Design (CAD) file using a 3-D modeling program which is used for the formation of a completely new object or making use of a 3-D scanner in order to copy an already existing object. This scanner also forms a 3-D digital copy of an object and puts this into a 3-D modeling program when done. Also, in order to prepare the digital file created in a 3-D modeling program for printing, the software slices the final output model into hundreds or thousands of horizontal layers. The printer makes the object layer by layer when this prepared file is uploaded into the 3-D printer. The 3-D printer reads every slice of layer or 2-D image and then goes ahead to create the object by blending each layer together without any sign of the layering visible, thereby resulting in a one three-dimensional object.
METHODS AND TECHNOLOGIES OF 3D PRINTING
It is important to note that it is not all 3-D printers that use the same kind of technology to get their objects processed. There are various ways to do it and all those procedures available as of 2012 were additive, this method being different mainly in the way the layers are built to create the final object. Some methods tend to use softening or melting material to produce the layers. Selective laser sintering (SLS) and fused deposition modeling (FDM) are part of the most common technologies that uses or makes use of these way of printing in 3D. Another style of printing is to lay liquid materials that are cured with different technologies, though the most common technology that uses this method in printing is called stereolithography (SLA).
SELECTIVE LASER SINTERING (SLS)
This technology makes use of a high powered laser to fuse small particles of plastic, metal, ceramic or glass powders into masses that has the desired three way dimensional shape. The laser then fuses the powdered material selectively by scanning the cross-sections or layers generated by the 3D modeling program on the surface of a powder bed. The powder bed is lowered by one layer thickness; this is after each cross-section is scanned. Then a new layer is applied on top of it and the process is done over and over until the object is completed.
Since all the untouched powder remains the way it is and becomes a support beam for the object. There becomes no need for any support structure which is an advantage over SLS and SLA. All unused powder can also be used when the next printing is to be done. SLS was developed and patented by a Dr. Carl Deckard at the Texas University in the mid-1980s, sponsored by DARPA.
FUSED DEPOSITION MODELING (FDM)
The FDM technology works by using a plastic filament or metal wire which is unwound from a coil and supplies the material to an extrusion nozzle that can turn the flow on and off at will. The nozzle is then heated to melt the material and can be moved in both the vertical and horizontal directions by a number controlled mechanism, which is in turn directly controlled by a computer-aided manufacturing (CAM) application package. The object is made by extruding melted material in order to form layers as the material hardens immediately after extrusion from the nozzle is completed.
Scott Crump who invented FDM in the late 80’s, after patenting this technology he had started the company called Stratasys in year 1988. The software which most times come with this technology automatically creates support structures if it is required. The machine then dispenses two materials; one form is a disposable support structure and the other one for model.
The term known as fused deposition modeling and its abbreviation FDM are both trademarked by Stratasys Inc., and the exact equivalent term, fused filament fabrication (FFF), was then formed by the members of the RepRap project in other to give a phrase that would be legally accepted in its use.
The main technology in which photopolymerization is usually used to produce a solid part from a liquid is known as the SLA. This technology makes use of a vat of liquid ultraviolet and curable photopolymer resin as well as an ultraviolet laser in other to build the object’s layers one at a time. Also, for each layer, the laser beam trails a cross-section of the part pattern found on the surface of the liquid resin. Been exposed to the ultraviolet laser light also cures and makes the pattern traced on the resin solid and joins it to the layer below it. After this pattern has been traced, the SLA’s elevator platform then comes down by a distance which equals to the thickness of a single layer, typically 0.05 mm to 0.15 mm. The resin-filled blade then sweeps across the cross-section of the part, re-coating it in the process with fresh material. On this particular new liquid surface, subsequent layer pattern is then traced, joining the former layer. The complete three-dimensional object is created by this project. Stereolithography employs the use of supporting structures which also serves to attach the part to the elevator platform used.
This technique which was invented in 1986 by Charles Hull, who also at the time founded the company, 3D Systems.