Final Presentation�� DE ZG628T: Dissertation

Design Optimization Through Different Multiscale Structures

BITS Pilani

Pilani Campus

Content

• Abstract
• Introduction to Multiscale Structure
• Parameters used in lattice conversion
• Types of Multiscale Structure
• Types of Lattice Structures Available in library of Materialise Magics
• Selection of Multiscale Structure
• Hybrid Design Integration of Selected Lattice Structure with the Part
• Development of the selected Design
• Benefits over selection of lattice
• Conclusions and Recommendations

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Abstract

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Metal Additive Manufacturing, particularly Direct Metal Laser solidification (DMLS) has enabled development of the lattice structures with unique properties. Through control of various parameters lattice structures can produce unique mechanical, electrical, thermal, and acoustic properties, and have received much research attention. Despite the increasing volume of published data on the mechanical response of the specific DMLS lattice structures, there exits no overarching analysis.

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The Diamond 20% relative lattice structure has been proven the best one with respect to DMLS machine environment and our study has covered the same.

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Keywords: Additive Manufacturing, SLM, DMLS, Lattice structures; DfAM; mechanical properties, Diamond 20% relative lattice structure.

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Project Areas: Design of Experiment, Design for Additive manufacturing

Introduction To Multiscale Structure

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Multiscale Structures commonly known as Lattice structures – are topologically ordered, three dimensional open called structures composed of one or more repeating unit cells.

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These cells are defined by the dimensions and connectivity of their constituent strut elements, which are connected at specific nodes.

Solid CAD data

CAD with lattice structures

Physical Printed Lattice Structure

Parameters used in Lattice conversion

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We had selected No outer shell to see the clear results of the lattice getting printed.

The structure chosen was 20% diamond relative kind with 10 mm strut parameter in all the directions.

Types of Lattice Structure

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There are three classes of lattice structure known broadly as:

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1- Strut-based lattice structures

2- Triply Periodic minimal surface lattice structures

3- Shell lattice structures

Types of Lattice Structures Available in �Library of Materialise Magics

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Types of Lattice Structures Available in �Library of Materialise Magics

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Types of Lattice Structures Available in �Library of Materialise Magics

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Selection of Multiscale Structure

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Hybrid Design Integration of Selected �Lattice Structure with Part

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The Design integration with lattice structure has been done as follows:

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1. The original CAD DATA has been converted into .stl format and it was sectioned by approx. 120 degree to see the visuals of the Lattice getting printed and to remove powder trapped inside.
2. The same CAD has been converted into lattice (Diamond 20% relative type) without shell setting.
3. The original CAD data is then shelled with wall thickness of about 1.3 mm.
4. The shell model is then unified with lattice model to get the final design.

Development of the Selected Design

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The development of the prepared design is done through special manufacturing process called Direct Metal Laser Solidification Process. The factors which are responsible for development of this design are as follows:

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1- Orientation: The orientation has always been a vital phase of the manufacturing technology DMLS however in this case the inner structures (lattice structures) themselves are acting like supporting geometry also and with putting the orientation right-side-up, the manufacturing could be done with negligible supports. The orientation of the Selected design is shown in the image given.

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Development of the Selected Design Cond…

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2- Processing Parameters (Exposure Parameters): The process Parameters are the inputs to the laser are known as the exposure parameters in DMLS technology. These are Laser Power, Laser Scanning Speed, Hatch Distance, Stripe Width, Laser Beam Diameter, Laser Beam Offset etc. The detailed values are shown the table.

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Development of the Selected Design Cond…

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3- Assignment of Process Parameter: The oriented design is then exported into common layer interfaces (.cli) and slices where each layer is sliced with 10 micron layer thickness and then converted into slice (.sli). These slices are then imported into the mainframe computer of the DMLS machine i.e. EOS M280 used in our case. These slices are assigned with exposure parameters that are explained in previous slide and then the build starts for printing.

Development of the Selected Design Cond…

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4- Printing Process: Before printing starts the build is thoroughly checked for orientation and layer wise observation if there are any defect, those are addressed at the time of the data preparation stage only.

Development of the Selected Design Cond…

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5- Post Processing: Once the printing completes the printed build undergoes the following processes to get final finished part.

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1. Heat Treatment (Stress Relieving)
2. Powder Removal
3. Part detachment from build
4. Support removal
5. Grinding
6. Polishing
7. Machining
8. Shot Blasting

Benefits over selection of lattice

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• Save Powder: The lattice structure integration helps saving powder and thus manufacturing cost getting fabricated through Direct Metal Laser Solidification (DMLS).

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• Keep the Temperature Under Control: In DMLS technology lattice structures help stabilizing the temperature during laser scanning which eventually reduces distortion on the parts getting printed.

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• Enhance the Design: The design looks more appealing with integrated solid mass reducing the weight. It helps creating porous designs for bone and tissue ingrowth.

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• Freedom of the Design: By using the module’s structures library or design we own unit cell structures to create lattices.

Conclusions and Recommendations

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This work has sought to overcome this limitation by providing an overview of the literature regarding SLM/DMLS Multiscale Structures commonly known as lattice structures, with 20% Diamond relative type lattice structure. Key findings of this analysis include:

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1. Diamond 20% relative lattice structure is found superior among other options available in Materialise Magics for Hybrid design consolidation using lattice structure.
2. 45% of the weight reduction is noted in one of the impeller’s examples taken in the study.
3. The cost has been reduced for the manufacturing with comparatively less amount of the mass being printed.
4. The performance eventually increases with decreased amount of the mass.
5. The structure’s parameters are important when it comes to design and the analysis of the same with respect to DMLS (Direct Metal Laser Solidification) machine environment makes it perfect example for printing.
6. The Other structures are found to be stiffer and non-conforming to the solid re-coater fabrication technique thus are difficult to be processed as compared to Diamond 20% relative type lattice Structure.
7. DMLS allows the fabrication of multiscale structures (e.g. scaffolds) with virtually any designs for load-bearing and biological functions; however, there are still research challenges to overcome in order to fully exploit the opportunities of this technology.

THANK YOU

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Presenter: Arun Kumar

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BITS ID: 2019HT30599

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Course: BITS DE ZG628T: Dissertation

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Organization: Innovae 3d Pvt. Ltd.

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Location: Pune

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Contact: +91-7704955357

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