Types of 3D Printers: All there is to know and choose from in 2018
The world of 3D printing can be a confusing place for newbies and amateurs. With so many printing techniques and types of 3D printing machines, there is bound to be confusion. What is SLA? How is it different from SLS or SLM? Which is better? Which one offers a greater degree of precision? Which is more cost-effective?
Before moving on to different types of 3D printers, it is imperative to understand the basics of 3D printing or Additive Manufacturing as it known in technical terms.
Additive Manufacturing in an umbrella term used to describe different types of technologies used to create 3D objects by the process of layering the raw material used. So when we talk about different types of 3D printers, we are essentially talking about the different technologies being used for creating objects in 3D. The materials used for this purpose range from plastic filament to powder, liquid, wood, and even paper, depending upon the type of 3D printing technique that a particular machine is built on.
To begin 3D printing or Additive Manufacturing, you need a computer with special software for 3D modeling. The first step is to create a CAD sketch of the model you intend to 3D print. The 3D printer or AM device reads this CAD sketch and begins to build a structure by adding layer-upon-layer of the raw material in the desired shape and structure.
Over the past three decades, Additive Manufacturing or 3D Printing has evolved a great deal, giving way to different printing technologies such as Stereolithography(SLA), Digital Light Processing(DLP) and Fused deposition modeling (FDM). Different 3D printing methods have been developed to create different 3D structures and objects. Some of these methods have soared in popularity, while others have failed to stand the test of time.
The following 3D printing techniques – or types of 3D printers, in lay terms – are among the most popular:
- Stereolithography (SLA)
- Digital Light Processing (DLP)
- Fused Deposition Modeling (FDM)
- Selective Laser Sintering (SLS)
- Selective Laser Melting (SLM)
- Electronic Beam Melting (EBM)
- Laminated Object Manufacturing (LOM)
In this guide, we will focus on each of these 3D printing technologies to understand how they work and how similar or different they are to one another:
Stereolithography (SLA) 3D Printers
Stereolithography or SLA is one of the earliest printing methods in the history of 3D printing and one that remains in vogue to this day. The one thing that stands out the most about SLA 3D printers is the range of application that this printing method brings to the table. Whether you want to build different parts of a creative design or create prototypes for a project, SLA printers do the job of bringing 3D models to life rather well.
An SLA-based 3D printer runs on excess liquid plastic that has the property to harden and take solid form. Owing to the nature of the material used for printing with SLA printers, the end product usually has a smooth finish to it. Once the plastic filament has hardened, a fraction of a millimeter of this filament is dropped down in the tank and the laser fitted in the printer continues to form layers until the design is complete. Once all the layers have been printed, the object is rinsed with the special solvent and then passed through an ultraviolet oven to finish off the printing process.
The time required to get a 3D print ready with an SLA printer depends on the specifications of the printer as well as the size of the design. While smaller objects can be printed in about 6-8 hours, working on large or complex prints can take several days.
Digital Light Processing (DLP) Printers
This printing technology was developed by Larry Hornbeck of Texas Instruments in 1987 and became popular for its extensive use in projectors production. A DLP printer uses digital micromirrors set on a semiconductor chip for the printing process. The DLP Printers are similar to their SLA counterparts in the sense that they both function on photopolymers. The underlying difference, however, is that DLA printers require an additional light source whereas SLA printers can function well without it.
Beginners usually rely on traditional light sources such as arc lamps to supplement the requirements of a DLP printer. Another unique aspect of DLP printers is their use of LCD panels that is applied to the surface of every 3D printed layer during the printing process. DLP printers use a liquid plastic resin as their raw material, which is typically set in a transparent container. When exposed to bright light (or a high concentration of photons), the resin hardens within no time. In that aspect too, the DLP is similar to SLA. The biggest drawcard for DLP printers is their printing speed. It takes just a few seconds to print a single layer of hardened material with these printers, and once you have transferred the layer from the print bed, the process of next layers gets started.
Fused Deposition Modeling (FDM) Printers
If one has to choose the most popular 3D printing technology in the present time, FDM would emerge as a clear frontrunner. Most 3D printers, be it DIY kits or pre-assembled variants, available in the market today are developed on this technology that was created by Scott Crump from Stratasys in the 1980s. Over the years, many manufacturers have embraced this technology only to implement it under different names.
A popular variant of FDM printers is the Fused Filament Fabrication (FFF) printers. FDM printers are widely used not just for printing operations prototypes but also actual ready-to-use products such as plastic gears, Lego, jewelry, and more. The basic fundamental of 3D printing, that is layer-by-layer construction, applies to FDM printers as well, but here the objects are built from the bottom up on a heated bed and with help of an extruding thermoplastic filament.
The 3D printer heats up the filament until it reaches its melting point and then releases it through the extrusion nozzle on the printing bed. FDM printers are equipped to support a wide range of printing materials in addition to the thermoplastic. The printer is governed by Slicer software that controls the operations of its X, Y and Z axis coordinates as well as the extrusion nozzle. The only drawback of an FDM printer in comparison to an SLA or DLP printer is the slower printing speed. However, it more than makes up for this lack of speed with its high-quality, manufacturer-grade 3D objects. FDM printers are widely being used by architects, automobile companies, toy manufacturers, as well as in the food and medical sector.
Selective Laser Sintering (SLS) Printers
The SLS 3D printers rely on using a laser as a power supply source to build sturdy 3D printed objects. SLS printers are quite different from variants such as FDM and SLA printers as they do not rely on supporting structures for 3D printing and instead use non-sintered powder. A CAD sketch of the design required to be printed needs to be converted into a .stl format for printing with an SLS 3D printer. SLS printers can support a wide range of printing materials, ranging from nylon to glass, ceramics, and even metals such as steel, silver or aluminum.
This versatility of printing materials makes SLS printers a preferred choice for those who like to create customized goods with 3D printing. However, owing to the requirement of high-powered lasers and the consequent high cost of these printers, more often than not restricts their usage to business establishments and manufacturers instead of 3D enthusiasts and amateurs.
Selective Laser Melting (SLM) Printers
SLM printers use high-power laser beams to fuse and melt metallic powders together, which are then used to build 3D objects by using CAD data as the source. Given the striking similarities in their printing techniques, SLM printers are often considered an offshoot of SLS printers. However, this isn’t exactly true as SLM printers melt the printing material to create solid 3D objects as opposed to the selective sintering process used in SLS printers.
The SLM printers also require the CAD file to be sliced by special software and broken down into 2D layers. Once the printer’s software reads the file and assigns values for construction, the printing process begins by evenly spreading out fine metal powder onto a plate. The printer then begins printing each 2D layer with help of high laser energy that melts the powder completely and leads to the formation of a solid structure. The same process is repeated layer after layer until the entire design comes together. SLM printers can be used to create 3D object aluminum, cobalt chrome, stainless steel, and titanium.
Electronic Beam Melting (EBM) Printers
EBM printers are another type of 3D printers that are primarily used to create 3D objects with metal parts. The process of EBM printers is nearly identical to that of SLM printers, except that EBM uses an electron beam instead of a high-power laser beam used by their SLM counterparts. The process of melting the metal powder is carried out at extremely high temperatures, going up to 1000°C.
EBM printers do not enjoy an enviable popularity on account of being slower and costlier, besides limited material support. For now, the application of EBM printers is primarily confined to aerospace and medical implants sectors.
Laminated Object Manufacturing (LOM) Printers
In Laminated object manufacturing (LOM) printers, layers of adhesive-laced paper, metal laminates or plastic are fused together using pressure and heat and cut using a computer-controlled knife or laser. The unique aspect of LOM is the post-processing of 3D printed parts to give it the desired shape and structure.
Printing with LOM 3D printers require a CAD file to be converted to .stl or 3DS format. A sheet coated with adhesive is laid down on the substrate and a heated roller is moved over the materials to melt the adhesive. A knife or laser is then used to cut the layer into desired dimensions and shape, and any excess material is removed. The platform is then moved slightly and a new sheet is added to the substrate. The process is repeated until the object is fully printed.