Direct Metal Laser Sintering(DMLS)

Direct metal laser sintering (DMLS) Is an additive manufacturing technique that uses a laser as the power source to sinter powdered material (typically metal), aiming the laser automatically at points in space defined by a 3D model, binding the material together to create a solid structure.
.ss. Metal powder (20μm diameter) without binder is completely melted by scanning of a high power laser beam. The density of a produced part is about 98 %. SLS has about 70 %. One advantage of DMLS compared to SLS is the small size of particles which enables very detailed parts.
Working principle:
Direct metal laser sintering (DMLS) is an AM process by which digital 3Ddesign data is used to build up a component in layers by depositing metal material.
The system starts by applying a thin layer of the powder material to the building platform
After each layer, a laser beam then fuses the powder at exactly the points defined by the computer-generated data, using a laser scanning optic . The platform is then lowered and another layer of powder is applied . Once again the material is fused so as to bond with the layer below at the predefined points resulting in a complex part. Thereby not only the part but also the final material is created in the process and defines the unique characteristics of this technology. Every single welding line creates a new micro segment of the final part and can therefore be monitored. Stacking all monitoring information on top of each other, we can visualize a 3D model of the part quality.

1. DIRECT METAL LASER SINTERING(DMLS)

2. Introduction: What is Rapid Prototyping ? Rapid prototyping is a group of techniques used to quickly fabricate a scale model of a physical part or assembly using three-dimensional computer aided design (CAD) data . Fig-1 CAD Model Fig-2 Finished Part

3. History The roots of Rapid Prototyping can be traced to Topography & Photo sculpture Topography was first proposed by Blanther in 1890. Photo sculpture for 3D replicas of objects were proposed by B ogart in 1969 . Fig-3: Topography Fig-4: Photo sculpture 3D

4. Fundamentals of Rapid Prototyping RP techniques employ the some basic five-step process 1.Creating the 3D CAD model of the design 2.Converting the CAD model into STL format (stereo lithography) 3.Slicing the STL file into thin cross-sectional layers 4.Constructing the model one layer atop another 5.Cleaning and finishing the model

5. 1. 2. 3. 4. 5. Fig-5: Basic Steps in RP Technology

6. Classification of RP Systems 1. Liquid-Based 2. Solid-Based 3. Powder-Based

7. Direct Metal Laser Sintering (DMLS ) Direct metal laser sintering (DMLS) Is an additive manufacturing technique that uses a laser as the power source to sinter powdered material (typically metal), aiming the laser automatically at points in space defined by a 3D model, binding the material together to create a solid structure .

8. Working principle: Fig-6: Step by step procedure of DMLS

9. Metal Powders used Stainless steel 17-4 Aluminum Titanium Ti-64 Nickel alloy IW 718

10. Advantages of DMLS High speed: Because, no special tooling is required, parts can be built in a matter of hours. Complex geometries: C omponents can be designed with internal features and passages that cannot be cast or otherwise machined . High quality: DMLS creates parts with high accuracy and detailed resolution.

11. Medical field Application Aerospace Industries Manufacturing Automotive

12. Limitations Surfaces need to be polished. Removing metal support structures and thermal post-processing is time consuming (you can’t have the supports in a different material than the part)

13. Case Study Titanium glasses using metal additive manufacturing Fig-7: Titanium glasses The eye venture decided to look into the possibility of using additive manufacturing in titanium as this eliminated the need for tooling and also allowed flexibility in future interchangeable designs of the frame can be made by CAD data and the parts rebuilt quickly and cost effectively .

14. Conclusion The DMLS uses high intensity laser source and imparts the energy over the metal powder as per the required geometry pattern ,melts below it’s melting point and solidifies the metal powder to the deposited layer without affecting the material properties. DMLS process used for the actual material needed to make the part at one build time, there by eliminates the secondary machining. DMLS eliminates tool change & production line cost resulting in small batch & single part build cost efficiency.

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