3D Printer & Its Types with their Working Principles

 3D Printers & Its Working

                     A 3D printer is a computer-aided manufacturing (CAM) device that creates three-dimensional objects. Like a traditional printer, a 3D printer receives digital data from a computer as input. However, instead of printing the output on paper, a 3D printer builds a three-dimensional model out of a custom material.

3D printers use a process called additive manufacturing to form (or "print") physical objects layer by layer until the model is complete. This is different than subtractive manufacturing, in which a machine reshapes or removes material from an existing mold. Since 3D printers create models from scratch, they are more efficient and produce less waste than subtractive manufacturing devices.

- 3D Printers Types

1) Stereolithography (SLA) Technology

                                                                SLA is a fast prototyping process. Those who use this technology are serious about accuracy and precision. It can produce objects from 3D CAD data (computer-generated) files in just a few hours. This is a 3D printing process that’s popular for its fine details and exactness. Machines that use this technology produce unique models, patterns, prototypes, and various production parts. They do this by converting liquid photopolymers (a special type of plastic) into solid 3D objects, one layer at a time. The plastic is first heated to turn it into a semi-liquid form, and then it hardens on contact. The printer constructs each of these layers using an ultra violet laser, directed by X and Y scanning mirrors. Just before each print cycle, a re coater blade moves across the surface to ensure each thin layer of resin spreads evenly across the object. The print cycle continues in this way, building 3D objects from the bottom up.

Once completed, someone takes the 3D object from the printer and detaches it carefully from the platform. The 3D part will usually have a chemical bath to remove any excess resin. It’s also common practice to post-cure the object in an ultra violet oven. What this does is render the finished item stronger and more stable. Depending on the part, it may then go through a hand sanding process and have some professional painting done. SLA printing has become a favored economical choice for a wide variety of industries. Some of these include automotive, medical, aerospace, entertainment, and 

also to create various consumer products.

2) Digital Light Processing (DLP) Technology

                                                                   DLP is the oldest of the 3D printing technologies, created by a man called Larry Hornbeck back in 1987. It’s similar to SLA (see above), given that it also works with photopolymers. The liquid plastic resin used by the printer goes into a translucent resin container. There is, however, one major difference between the two, which is the source of light. While SLA uses ultra violet light, DLP uses a more traditional light source, usually arc lamps. This process results in pretty impressive printing speeds. When there’s plenty of light, the resin is quick to harden (we’re talking seconds). Compared to SLA 3D printing, DLP achieves quicker print times for most parts. The reason it’s faster is because it exposes entire layers at once. With SLA printing, a laser has to draw out each of these layers, and this takes time.

Another plus point for DLP printing technology is that it is robust and produces high resolution models every time. It’s also economical with the ability to use cheaper materials for even complex and detailed objects. This is something that not only reduces waste, but also keeps printing costs low.

3) Fused Deposition Modeling (FDM) Technology

                                                                                    FDM is a 3D printing process developed by Scott Crump , and then implemented by Stratasys Ltd., in the 1980s. It uses production grade thermal plastic materials to print its 3D objects. It’s popular for producing functional prototypes, concept models, and manufacturing aids. It’s a technology that can create accurate details and boasts an exceptional strength to weight ratio.

Before the FDM printing process begins, the user has to slice the 3D CAD data (the 3D model) into multiple layers using special software. The sliced CAD data goes to the printer which then builds the object layer at a time on the build platform. It does this simply by heating and then extruding the thermoplastic filament through the nozzle and onto the base. The printer can also extrude various support materials as well as the thermoplastic. For example, as a way to support upper layers, the printer can add special support material underneath, which then dissolves after the printing process. As with all 3D printers, the time it takes to print all depends on the objects size and its complexity.

Like many other 3D technologies, the finished object needs cleaning. Raw FDM parts can show fairly visible layer-lines on some objects. These will obviously need hand sanding and finishing after printing. This is the only way to get a smooth, end product with an even surface. FDM finished objects are both functional and durable. This makes it a popular process for use in a wide range of industries, including for mechanical engineering and parts manufacturers. BMW uses FDM 3D printing, as does the well-known food company Nestle, to name just a couple.

4) Selective Laser Sintering (SLS) Technology

An American businessman, inventor, and teacher named Dr.Decard developed and patented SLS technology in the mid-1980s. It’s a 3D printing technique that uses high power CO2 lasers to fuse particles together. The laser sinters powdered metal materials (though it can utilize other materials too, like white nylon powder, ceramics and even glass). Here’s how it works:

The build platform, or bed, lowers incrementally with each successive laser scan. It’s a process that repeats one layer at a time until it reaches the object’s height. There is un-sintered support from other powders during the build process that surround and protect the model. This means the 3D objects don’t need other support structures during the build. Someone will remove the un-sintered powders manually after printing. SLS produces durable, high precision parts, and it can use a wide range of materials. It’s a perfect technology for fully-functional, end-use parts and prototypes. SLS is quite similar to SLA technology with regards to speed and quality. The main difference is with the materials, as SLS uses powdered substances, whereas SLA uses liquid

 resins. It’s this wide variety of available materials that makes SLA technology so popular for printing customized objects.

5) Selective Laser Melting (SLM) Technology

A common use for SLM printing is with 3D parts that have complex structures, geometries and thin walls. The aerospace industry uses SLM 3D printing in some of its pioneering projects. These are typically those which focus on precise, durable, lightweight parts. It’s a costly technology, though, and so not practical or popular with home users for that reason. SLM is quite widespread now among the aerospace and medical orthopedics industries. Those who invest in SLM 3D printers include researchers, universities, and metal powder developers. There are others too, who are keen to explore the full range and future potential of metal additive manufacturing in particular.

6) Electron Beam Melting (EBM) Technology

A Swedish company called Arcam AB founded EBM in 1997. This is a 3D printing technology similar to SLM (see above), in that it uses a powder bed fusion technique. The difference between the two is the power source. The SLM approach above uses high-powered laser in a chamber of noble, or inert gas. EBM, on the other hand, uses a powerful electron beam in a vacuum. Aside from the power source, the remaining processes between the two are quite similar. EBM’s main use is to 3D print metal parts. Its main characteristics are its ability to achieve complex geometries with freedom of design. EBM also produces parts that are incredibly strong and dense in their makeup.

Summing Up

3D printers and print technology is advancing all the time. As it does, prices will continue to fall as the devices and processes become ever more impressive. If you’ve read this guide from top to bottom, you will now have a good basic understanding of the different 3D printers and how they work. You will also know of the various materials printers use and the industries they support. And if you need a refresher, you can simply revisit any section of this guide at any time.