Metal 3D Printing: Advanced Design Techniques

Forgelabs DMLS Metal 3d Printing 1

Metal 3D Printing:

Advanced Design Techniques

Written by: Ron Luther, Manufacturing Specialist - April 11, 2024

Additive manufacturing in metal can be an incredibly powerful tool for producing geometries that are difficult or impossible to create any other way. As industries from aerospace to medical devices increasingly rely on metal 3D printing, understanding advanced design techniques becomes crucial for engineers and designers seeking to fully leverage DMLS's capabilities.

Understanding DMLS

Before diving into design techniques, it's essential to grasp the fundamentals of DMLS. This process involves the use of a laser to sinter powdered metal, layer by layer, to form solid metal parts. Unlike traditional manufacturing methods, DMLS can produce parts with complex geometries, internal features, and high levels of customization without the need for tooling. Learn more about DMLS by reading our Metal 3D printing overview.

Design Considerations for DMLS

When designing for DMLS, several key factors must be considered to ensure the success of the final product. These include part orientation, support structures, feature resolution, and thermal considerations.

Part Orientation


The orientation of a part on the build platform significantly affects its surface quality, mechanical properties, and the necessity for support structures. Orienting a part to minimize the amount of support needed can reduce post-processing time and material waste. However, orientation must also take into account the part's critical features and intended use to optimize its strength and functionality.

Support Structures


Support structures are often necessary in DMLS to uphold overhanging features and dissipate heat during the printing process. Designing these supports to be easily removable and minimizing their use through strategic part orientation can streamline post-processing and improve the overall efficiency of production.

Feature Resolution


DMLS is capable of producing very fine features, but there are limitations. Understanding the resolution capabilities of the DMLS printer being used is vital to ensuring that designs are both manufacturable and meet the required specifications. Small features, thin walls, and fine details must be designed within the printer's capabilities to ensure accuracy and integrity. You can learn more about the constraints particular to DMLS in our DMLS Design Guideline.

Thermal Considerations


DMLS involves high temperatures and rapid cooling, which can lead to residual stresses and distortion in printed parts. Designing to minimize these stresses — for instance, by including thermal dissipation features or optimizing geometry for uniform cooling — is critical. Simulation software can be invaluable in predicting and mitigating thermal issues.

Advanced Techniques for Optimizing DMLS Designs

Beyond basic considerations, several advanced techniques can be employed to optimize designs for DMLS:

Topology Optimization


Topology optimization software can be used to optimize material distribution within a design based on load conditions and constraints, resulting in parts that are lightweight yet strong. This technique is particularly useful in aerospace and automotive applications where weight reduction is critical. You can learn more about topology optimization in our blog post: Topology Optimization For 3D Printing.

Software used for Topology Optimization:

    • Altair HyperWorks (OptiStruct)
    • ANSYS Mechanical
    • Autodesk Fusion 360
    • Dassault Systèmes SIMULIA (Tosca)
    • PTC Creo
    • Siemens NX
    • SolidWorks Simulation
    • nTopology
    • Grasshopper3D (with plugins like Karamba3D)

Lattice Structures


Topology optimization software can be used to optimize material distribution within a design based on load conditions and constraints, resulting in parts that are lightweight yet strong. This technique is particularly useful in aerospace and automotive applications where weight reduction is critical. You can learn more about topology optimization in our blog post: Topology Optimization For 3D Printing.

1. Determine what you need to achieve with your part. This could include weight reduction, increased mechanical strength, specific stiffness, or enhanced thermal conductivity.

2. Select an appropriate lattice geometry (such as cubic, diamond, or gyroid). The chosen geometry will significantly influence the part's mechanical and thermal properties.

Lattice Variables:

Cell Type

Shape of the repeating unit in the lattice (e.g., cubic, octahedral).

Cell Size

The dimensions of the individual cells within the lattice.

Strut Thickness

Diameter of the connections (struts) between nodes in the lattice.

Density

Overall compactness of the lattice within the part, affecting both strength and weight.

3. Choose the right software. Employ advanced design and simulation software capable of handling complex lattice structures and topology optimization. These tools are essential for visualizing, simulating, and refining your design.

Once you’ve figured out what you’re going to use, iterate on the design, optimizing lattice parameters (strut thickness, cell size, etc.) for the desired performance outcomes. Simulation can predict how the part will respond to real-world stresses and thermal conditions, so it is invaluable for narrowing the scope of possible solutions before committing to physical testing.

Software used for designing lattice structures

Autodesk Fusion 360 (using Generative Design extension)

nTopology

ANSYS SpaceClaim

Grasshopper (within Rhinoceros 3D)

SolidWorks

Altair Inspire

4. Tailor Lattice Parameters to Printer Capabilities. Adjust the lattice design to match the resolution and capabilities of the DMLS printer. This includes ensuring that features like strut thickness and cell size are within the printable range to avoid manufacturing defects.

Optimize the design to use material where it contributes most to the part’s performance, reducing waste and cost, and make sure that the lattice design is as self supporting as possible in the intended print orientation to avoid time consuming support removal between cells. 

Generative Design


Generative design algorithms can explore a vast design space to identify optimal designs that a human designer might not consider. By inputting design goals and constraints, these algorithms can generate optimized design options, often resulting in innovative and efficient structures. Note that the phrase “garbage in, garbage out” still applies here - your results will depend on how rigorously you define the goals and constraints, and the selected output will likely need further adjustment to come up with a finished part.

Software used for Generative Design:

Autodesk Fusion 360 (using extension)

Siemens NX

Ansys Discovery

SolidWorks

PTC Creo

nTopology

Altair Inspire

Simulation and Analysis


Utilizing simulation and finite element analysis (FEA) tools during the design process can help predict how a part will perform under various conditions. This can be particularly useful in identifying and addressing potential issues related to thermal stress, deformation, and mechanical failure modes before printing.

Software used for Finite Element Analysis:

ANSYS (ANSYS Mechanical)

Autodesk Nastran

Dassault Systèmes SIMULIA Abaqus

COMSOL Multiphysics

Siemens PLM Software NX Nastran

PTC Creo Simulate

Altair HyperWorks

SolidWorks Simulation

MSC Software (MSC Nastran, Patran)

Post-Processing Integration


Designing with post-processing in mind can significantly impact the efficiency and effectiveness of the DMLS process. This includes designing features that facilitate the removal of support structures, considering the effects of surface finishing or post-machining techniques, and ensuring that critical dimensions are achievable within the post-processing capabilities. Experienced designers learn to build these considerations into their CAD models and will often include offsets, allowances and additional features that aid in post-processing stages. This can also include additional parts printed alongside the workpiece that enable more tailored capabilities, such as jigs or tools derived directly from the workpiece geometry.

Advanced Manufacturing

If you are interested in learning more about how to design 3D printed metal parts, reach out to us at [email protected]! We have the advantage of handling additive metal parts every day, so we know our way around this technology and we’re happy to share our knowledge. Feel free to send us your design files and we can review them with you, provide feedback on design-for-manufacture considerations and help you refine and optimize your parts.