3D printing and prototyping
When designing a new part or component, engineers use CAD (Computer Aided Design) software such as Solidworks or Autodesk Inventor. These allow to create shapes and patterns which aggregate to solid 3 dimensional objects. The CAD software then allows to save this object in the form of a STL file which basically maps the surface of the object with triangles. This file is then uploaded to the 3d printer which reads it and proceeds to create the object vertically layer by layer following different processes described below.
Extrusion deposition is the method employed by most desktop 3D printers and consequently the most widely used in 3d printing. Here, a filament of thermoplastic (most common) or metal is passed through a heated nozzle to melt, deposit on a surface and harden instantly. The nozzle turns the flow of material on and off while motors displace it according to the 3d coordinates contained in the STL file.
Another process consists in the binding of granular materials. Powders of materials such as metals or plastics are deposited on a bed. Powerful lasers or binding agents are then applied to it according to the model’s coordinates to fuse and harden the beads layer by layer, starting from the bottom and progressing upwards. Technologies using this process are Selective Laser Sintering (SLS), Direct Metal Laser Sintering (DMLS), Selective Laser Melting (SLM) or Electron Beam Melting (EBM).
Photopolymerisation is also an interesting 3D printing technique. Processes such as Stereolithography (SLA) are based on the hardening of liquid materials into solid shapes. Here, baths of liquid polymers with photosensitive additives are exposed to controlled lighting which leads them to harden. Again, this process is applied from bottom to top through little increments where the shape being built is slowly displaced downwards as new material is solidified. This technique allows to obtain smoother plastic surfaces and therefore reduce the need for part post processing (smoothening, etc).
In the end, 3D printing is a real revolution in hardware development. It allows to materialise designs at record speeds and with similar aesthetic properties to finished products. Of course, engineering characteristics such as strength cannot be similar to those in a properly manufactured products but they are sufficient to test shapes, details and configurations before moving to the factory machinery. In turn, 3D printing saves designers considerable amounts of time and money and enables smaller entities to come up with great products and compete with the big guys, often less inclined to innovate from their comfortable leading position.