Hey, curious reader in this article we’ll learn about the various processes which can be used to get 3D Printed prototype or model. To start off with 3D printing turns digital 3D models into solid objects by building them up in layers also called as additive manufacturing. This technology came up in the’80s and has been developing over the years. It is widely told that 3D Printing will become the next big thing or pitched to be the next industrial revolution. Well, to reach that point there is still time and it has to become more friendlier, cost-efficient and quicker. New 3D Printing techniques keeps coming in periodically to combat those problems. That’s some information on 3D printing, now to the main topic of the blog ‘Different Technologies of 3D printing’.
Most commonly used techniques for 3D printing are
- FDM (Fused deposition modeling)
- SLS (Selective laser sintering)
- SLA (Stereolithography)
There are other 3D printing methods such as 3DP, SLM, etc but above listed are commonly used for 3D printing and are easily accessible than its counterpart.
Fused deposition modeling or widely known in its abbreviated form FDM is a method under Material Extrusion and was invented by Scott Crump in the late 80’s. The term fused deposition modeling and its abbreviation FDM are trademarked by Stratasys Inc. Fused filament fabrication (FFF), was coined by the members of the RepRap project to give a phrase that can be used without any legal issues.
Hence, while many people use the phrase ‘FDM’ they refer to FFF 3D printing, only Stratasys actually makes FDM 3D printers. Other manufacturers refer to the same process as thermoplastic extrusion or FFM or FFF.
The most common materials for FDM 3D printers are ABS and PLA.
The process works by melting plastic filament that is deposited, via a heated extruder, a layer at a time, onto a build platform according to the 3D data supplied to the printer. Each layer hardens as it is deposited and bonds to the previous layer. This continues until the product is formed
The FDM/FFF process requires support structures for any applications with overhanging geometries. For this a water-soluble material, which allows support structures to be relatively easily washed away, once the print is complete is used or alternatively, breakaway support materials are also possible, which can be removed by manually snapping them off the part. Support structures, have generally been a limitation of the entry level FFF/FDM 3D printers. However, as the systems have evolved and improved to incorporate dual extrusion heads, it has become less of an issue. The advantages of FFF/FDM are strong parts and it is an easy to print procedure while the disadvantages being poorer surface finish and requirement of support structures
The below image shows how FDM process works
Selective laser sintering is a type of powder bed fusion 3D printing technique. SLS was developed and patented by Dr. Carl Deckard at the University of Texas in the mid-1980s, under sponsorship of DARPA. Powder bed fusion uses a laser, electron beam or other heat source to selectively fuse successive powder layers of plastic, metal, ceramic or glass into a mass that has the desired three dimensional shape.
The laser selectively fuses the powdered material by scanning the cross-sections (or layers) generated by the 3D modeling program on the surface of a powder bed. After each cross-section is scanned, the powder bed is lowered by a roller which smooths the powder over the surface of the bed prior to the next pass of the laser for the subsequent layer to be formed and fused with the previous layer. And the process is repeated till the object is completed.
One of the key advantages of this process is that the powder bed serves as an in-process support structure and all unused powder can be used for the next print. Other advantage is that high temperature is used and it is chemical resistant.
However, on the downside, because of the high temperatures required for laser sintering, cooling times can be considerable with precision being limited to powder particle size and it has a rough surface finish.
The above image shows the SLS method being done to make a model
Stereolithography (SLA) is the most commonly used technology in Vat Photopolymerisation.
SLA is widely recognized as the first 3D printing process; it is certainly the first to be commercialized too. Photopolymerisation method of 3D printing has a container filled with photopolymer resin which is then hardened with UV light source. This was invented by Charles Hull in 1984, who subsequently founded 3D Systems.
The UV laser beam, traces the first slice of an object on the surface of this liquid, causing a very thin layer of photopolymer to harden. The perforated platform is then lowered very slightly and the process repeats until the entire object is completed and the platform can be raised out of the vat for removal. It requires support structures which serve to attach the part to the elevator platform and to hold the object because it floats in the basin filled with liquid resin. These structures need to be manually removed.
In terms of other post processing steps, many objects 3D printed using SLA need to be cleaned and cured. Curing involves subjecting the part to intense light in an oven-like machine to fully harden the resin. Vat photopolymerization 3D printers are expensive to run due to the cost of their photopolymer resins, but offer very high resolutions (detailed parts) and deliver excellent surface quality. However limiting factors include the post-processing steps required and the stability of the materials over time, which can become more brittle and they require support structures also.
This image shows SLA 3D printing of prototype part
Now that, we have learnt quite a bit about different 3D Printing processes with their pro’s and con’s, share this with your friends or colleagues so, they too can get a clear idea about the processes and help them learn more about 3D printing.
And you can start making your 3D printed parts/products with us.