Not many have heard of 3D printing, and for the select few that have, hardly any truly know how the technology works. Three-dimensional printing has started to capture the headlines because of its ability to implement selective and innovative products in one piece, but how? Now that 3D printing has become so popular and lucrative, the new technology has been drawing engineers around the globe to start asking the question how can we make this technology even better? Within the past decade 3D printing has moved from one original technique to a multifaceted and complex system that involves the implementation of many new scientific procedures. We are here to take a closer look at some of today’s current 3D printing technologies and how they work.

FUSED DEPOSITION MODELING

Fused Deposition Modeling begins with a three dimensional part designed in a computer software file such as CAD(computer aided design). Once the file is uploaded to the printer, the software breaks it down into thousands of layers. Coils of thermoplastics are then fed to an extrusion head where they are heated up beyond their glass transition phase allowing for smooth dispense. The thermoplastics are then deposited by the extrusion head in little small beads, and then hardened immediately in order to create very precise finished products. The thermoplastics are layered with a support material in order to hold up overhanging layers. Once one layer is finished the surfaced is lower and the extrusion head moves onto the next layer. When the product is complete, it is then removed from the printer and supporting layers are disposed. Fused Deposition Modeling is ideal for concept models, functional prototypes, manufacturing aids, and low volume end use parts. Fused Deposition Modeling is one of the first types of 3D printing technology, therefore over time it has become more efficient and perfected.

SELECTIVE LASER SINTERING

Selective Laser Sintering is a rapid prototyping technique that involves the use of a high power laser, directed by mirrors, to fuse different types of powders into a solid. A design is uploaded to the 3D printer and for each layer, two mirrors spin and rotate on a 360 degree dimension in order to draw the outline of the layer. When the laser hits to powder, depending on what type of powder it is, the laser immediately heats the substance past its glass transition temperature and fuses the small particles into a solid material. Once one layer is complete, the object is lower, a new layer of powder is swept over, and the process is repeated until the full three-dimensional object is done. One of the benefits of using laser technology is SLS does not require support structures because the part being constructed is surrounded by unsintered powder at all times. This allows for the construction of previously impossible geometrics.

STEREOLITHOGRAPHY

Similar to Selective Laser Sintering, Stereolithography is an additive manufacturing process that involves the use of a laser in order to cure material into a solid state. Where Stereolithography differs is the type of laser and material or “resin”. Stereolithography uses an ultraviolet curable photopolymer liquid and an ultraviolet light to develop the three-dimensional object. A beam of ultraviolet light traces an outline of the .05mm thick layer of the object guided by the Computer Aided Design programs and an array of mirrors. When exposed to the ultraviolet light the resin immediately hardens and the layered becomes solid. A new even coat of liquid is swept across the cross-section and the process is repeated until the object is complete. The main advantage of Stereolithography is its speed and ability to rapidly produce an object. Using this type of technology allows designers and manufacturers the ability to produce strong prototypes and molds within a day. At the same time Stereolithography 3D printers tend to lean a bit on the expensive side, ranging from $100,000-$500,000, and the resin itself can range from $80-$210 per liter.

POLYJET

PolyJet Additive Manufacturing takes the concept of Stereolithography by using ultraviolet light and resin, and applies it in way similar to how Inkjet document printers work. The printer head, also called the “Jet”, moves across the build tray while dispensing liquid photopolymer in a precise manner. Each little bead of photopolymer is released in order to match the layer of the 3D object. Directly after the photopolymer is dispensed, a UV light on the Jet head cures the liquid into a solid object. Each pass of the Jet head constructs a new layer that build up one at a time to create a 3D model or prototype. Immediately after completion, objects can be handled, but first they must be stripped of excess support material injected during the procurement process in order to bear overhangs and complicated geometrics. PolyJet 3D printing has many advantages including superior speed, quality, and precision. Yet, what sets PolyJet 3D printing apart from the rest is its ability to incorporate a wide variety of materials in a single print run. This feature enables manufactures and designers to develop models and prototypes that use many different materials, which opens the door for endless design possibilities.