Different types of the 3D Printing process: PART 2
By: Aditya Gonella
Tags: Innovation, Technology, 3d Modeling, 3D Printing, Additive Manufacturing

In the previous blog, we started learning about the different 3D printing processes, and let's continue the same in this blog too!!

MATERIAL JETTING (POLY JET) 3D PRINTING:

Material Jetting (MJ) is a special additive manufacturing process. The feature that makes it so special is that operates also 2D printers. In material jetting, a printhead (these are analogous to the printheads used for standard inkjet printing) dispenses droplets of a photosensitive material that solidifies under ultraviolet (UV) light, thereby building the part layer by layer. The materials that are used in the Material jetting process are thermoset photopolymers ( paintings) that come in a liquid form.

Material Jetting 3D printing creates a corridor of high dimensional accuracy with a veritably smooth face finish. Multi-material printing and a wide range of accouterments ( similar to ABS-like, rubber-like, and completely transparent materials) are available in Material Jetting.

source: https://www.researchgate.net/publication/325876280/figure/fig3/AS:639591040155653@1529501795569/Schematic-representation-of-the-material-jetting-process.png

WORKING:

First, the liquid resin is hotted to 30–60 degrees centigrade to achieve optimal density for printing. Also, the printhead travels over the figure platform and hundreds of small tiny droplets of photopolymer are jetted/ deposited in the locations given as input in the form of G-code. A UV light source that’s attached to the printhead cures the deposited material, solidifying it and creating the first subcaste of the part. After the layer is complete, the build platform moves to the next layer position, and the process repeats until the whole part is complete.

These printers print in a line-wise fashion. Multiple inkjet printheads are attached to the same carrier side-by-side and they deposit material on the whole print face in a single pass. This allows different heads to deposit different materials, thereby allowing multi-material printing, full-color printing. Support structures are always needed in material jetting and need post-processing to be removed.

The liquid material in Material Jetting is solidified through a process called photopolymerization. This is the same medium that’s used in SLA. But unlike SLA they don’t bear fresh post-curing to achieve their optimal parcels, due to the very small heights that are used. The typical subcaste height used in material jetting is 16–32 microns. Indeed this material jetting also requires support while printing. There are two types of finishing in this process lustrous, matte.

Having learned some of the types of 3D printing, we shall now shift our aspect towards SLM and DMLS. Currently, SLM technology is extensively being used in the disciplines of aerospace, automotive, medical fields, etc. SLM has made it possible to manufacture colorful corridors without the demand for any supplementary coffers. Also, DMLS have made their stage in the manufacture of the high-performance corridor in the automotive and aerospace diligence, medical prosthetics, tools, and much further. We shall now explore each of these generalities extensively to understand their work.

SELECTIVE LASER MELTING (SLM) & DIRECT METAL LASER SINTERING (DMLS) 3D PRINTING:

Selective Laser Melting (SLM) and Direct Metal Laser Sintering (DMLS) are two metal additive manufacturing processes that come under the umbrella of the powder bed fusion 3D printing family. These two technologies are quite similar as they use a laser to scan and selectively fuse the powdered metal particles which enables bonding them together resulting in the development of a part.

Now, having said the similarities, we start thinking about their differences as I mentioned earlier, they are quite similar but not entirely. Well, Can you think of any difference between them?

The difference between SLM and DMLS is that SLM uses metal powders with a single melting temperature and fully melts the particles completely, while in DMLS the powder is composed of materials with variable melting points that get fused at elevated temperatures. Let me make things easier for understanding, SLM produces parts from a single metal, whereas DMLS produces parts from metal alloys.

Now let us begin understanding the working of DSLM printing.

Image of Direct Metal Laser Sintering process

source:https://www.researchgate.net/publication/330249826/figure/fig1/AS:870142959448064@1584469656348/Schematic-diagram-of-direct-metal-laser-sintering-process.jpg

WORKING:

1. Firstly, the build chamber is first filled with inert gas to minimize the oxidation of the metal powder, and then it is

heated to the optimal build temperature.

2. Then a thin layer of metal powder is spread over the build platform and a high-power laser scans the cross-section of

the component.

3. This melts (or fusing) the metal particles together, thereby creating the next layer. The entire area of the model is

scanned, so the part built is completely solid.

4. Once the scanning process is complete, the build platform moves downwards by one layer thickness and spreads another thin layer of metal powder.

5. This process is repeated until the whole part is complete.

6. When the build process is finished, the parts are fully encapsulated in the metal powder.

7. After some time the bin cools to room temperature, then the excess powder is removed manually and the parts are typically heated.

8. Now the components are detached from the build plate via cutting, machining, or wire EDM and are ready to use. [Note: The layer height used in metal 3D printing varies from 20–50 microns. The metal powder is recyclable.]

Now we understand the basic working of DMLS. We shall now move forward to learn about Binder Jetting 3D printing. Binder Jetting has a varied range of applications that include full-color prototypes, highly precise metal parts, sand casting cores, and much more.

BINDER JETTING 3D PRINTING:

Binder Jetting comes under the umbrella of additive manufacturing processes. A binder is selectively deposited onto the greasepaint bed, relating these areas together to form a solid part one layer at a time. The components generally used in Binder Jetting are metals, sand, and ceramics.

Image showing the process of Binder Jetting

source:https://www.engineersgarage.com/wp-content/uploads/2019/07/Binder-Jetting-3D-Printing-Process-and-machine-01.jpg

WORKING:

1. Originally, a recoating blade spreads a thin layer of powder over the build platform.

2. Up next, a carriage with an inkjet nozzle passes over the bed, depositing small droplets of a binding agent (glue) selectively that bond the powdered patches together.

3. In full-color Binder Jetting, the colored ink is also deposited during this step.

4. When the layer is complete, the build platform moves down, and the blade coats the face. This process is also repeated until the whole component is complete.

5. After printing, the part is reprised in the greasepaint and is left to cure and gain strength.

6. The part is also removed from the powder bin and the footloose, redundant powder is removed by passing pressurized air.

The main advantage of binder jetting is that cling occurs at room temperature. This means that dimensional deformations connected to thermal effects such as warping or curling aren’t a problem in binder jetting. Binder jetting requires no support structures.

In the next part let’s know about the DIRECT ENERGY DEPOSITION and SHEET LAMINATION process, with that we are going to wrap us the different types of 3D Printing processes and jump into the next topic.

Meet you in the next part of my 3D Printing-Series!!🙂