3D Printing, also called as additive manufacturing, is an innovative manufacturing method of parts from digital mode by using layer-by-layer build-up approach. It produces in a very short time dense metallic parts with high precision.
Metal AM processes can be classified as Powder Bed Fusion based technologies PBF and Directed Energy Deposition DED based technologies. Main parameters of this process are type of input raw material, for example metal powder, and energy source used to form the part, for instance arc, electron beam.
Powder Based Fusion technology thermal energy selectively fuses regions of powder bed. Main processes of PBF based technologies are Direct Metal Laser Sintering DMLS laser cusing and electron beam melting EBM. As the sintering material DMLS uses uncoated pre-alloyed metal powders and a high power laser. It allows to produce very dense parts. In EBM heated powder bed of metal in a vacuum is melted and formed layer by layer using an electron beam energy source.
Direct Energy Deposition based technologies use thermal energy to fuse materials by melting. To DED belongs: Laser Engineered Net Shaping LENS, Direct Metal Deposition DMD, Electron Beam Free Form Fabrication EBFFF, arc based AM and much more. DMD depends on injecting a powder coupled with a fiber laser on a robotic arm. It is best for producing new parts, repairs or adding new features. It uses a focused electron beam in a vacuum environment to create a molten pool on a metallic substrate.
EOS manufactures equipment for metal AM focused on their Direct Metal Laser Sintering technology. What is exacly DMLS? It is a most preferred powder bed fusion technology because of short manufacturing time, cost effective assembly and wide variety of metal parts. It does not require castings. It is a laser-based rapid prototyping and tooling process. Net shape parts are fabricated in a single process and complex parts can be produced from 3D-CAD models by layer-wise solidification of metal powder layers. The principle is to bring the thin layer melt down by a laser beam. Building platform, dispenser unit, the laser system, precision optics, a high speed scanner and a computer with process software are forming the DMLS machine. Metal powder is stored in dispenser unit and the recoater is used for coating of metal powder of uniform layer thickness on steel base plates. A steel base plate is mounted on building platform. Prototype part or mould is built on building platform. A layer of metal powder of grain size is spread on a steel base plate. The laser beam sinters the first layer. The building platform moves down. The build rate depends upon accuracy and roughness. The recoater moves towards the dispenser. The dispenser moves up so that sufficient powder is taken by the recoater to spread a new layer of powder on the already sintered layer.The laser sinters the second layer and thus the process continues till part gets completed. The accuracy of builded parts is up to 0,05 mm. The steps of building a prototype include:
-Creation of 3D CAD model of prototype part/mould
-Converting the CAD model to .STL format
-Support structure definition and smoothing of corners/edges is required
-Slicing the .STL model in to thin layers
-The layer file .SLI is fed to DMLS-AM/Rapid Prototyping machine.
What does influence the price of the products? Typical factors are: laser scanning speed, laser power,number of laser and scanners, overlap area of multiple lasers, required roughness(layer thickness) and base plate preheating capability. Furthermore, the productivity is influenced by the powder handling and exchange in combination with the required cleaning of the build part in order to remove the remaining powder.
There are many applications of 3D printing technology. It can be applied in various industries- aerospace, automotive, dental, jewelry, oil and gas and much more. There are also a lot of advantages of additive manufacturing. Freedom of design, complexity for free, potential elimination of tooling, lightweight design, part consolidation by reducing assembly requirements... There is no doubt why 3D printing is becoming much more popular.
Kasia
Useful links:
https://www.youtube.com/watch?v=da5IsmZZ-tw
https://www.youtube.com/watch?v=gIIdzKZEWKE
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