Metal Stamping Guide

Design for Metal 3D printing

Topology optimization, lattice structures, design rules for metal 3D printing and more.

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Metal Stamping Guide

Design for Metal 3D printing

Designing for metal 3D printing requires a new mindset and comes with a unique set of design rules and best practices.

In this section, we introduce you to the basic principles and tools that will help you get the most out of your designs, such as topology optimization.

Design for Metal 3D printing

Key design considerations

A Metal Extrusion 3D printer in action
A Metal Extrusion 3D printer in action

Designing for an additive process follows a different set of rules than designing for “traditional” manufacturing. The unique design freedom, as well as the unique set of limitation, demand a shift in the mindset of the designer.

Here is a list of key ideas you should keep in mind while designing for metal 3D printing:

Key design consideration

Due to its high cost, it is rarely economically feasible to manufacture parts that have been designed for a traditional process using metal 3D printing.

Actually, it is often technically impossible to reproduce these geometries. For example, section thicker than 10 mm are prone to warping or other manufacturing defects and should be avoided.

Design complexity is often considered harmful, as it is connected to an increased cost. In metal 3D printing, this is not the case. On the contrary, finding a way to maximize the added value that geometric complexity brings to a system is key to take full advantage of the benefits of metal 3D printing.

When you begin to redesign a part or assembly for metal 3D printing, it is usually a good idea to start with a blank canvas. This way you can avoid being restricted by preconceived designs.

Clearly defining the design requirements (loads, boundary condition, part weight etc.) is key here. We will see in the next section that modern CAD software use these as input to create optimized structures with organic forms.

It is a good practice to have a clear vision of how the part will be orientated in the machine. Print orientation is important as it defines the position and need of support structures.

The aim of the designer should be to create parts with self-supporting features, minimizing the need for support and ensuring build success.

Independent of the process, post-processing is always required in metal 3D printing. This can be obligatory (such as support removal in DMLS/SLM or sintering in Binder Jetting and Metal extrusion) or optional (such as CNC machining step to achieve tighter tolerances or a heat treatment to improve material properties).

So it is essential to keep the post-processing requirements and available option in your mind while designing a part for metal 3D printing.

Design optimization tools & software

Modern CAD packages offer tools to help you take full advantage of the geometric freedom of metal 3D printing. Using these algorithm-driven design tools, you can create organic-like structures that outperform parts that were designed using traditional methods.

There are three main strategies that can be used today. These strategies can either optimize the performance of an existing design or help in the creation of structures from scratch based on a set of design requirements.

Design Metal 3D printing for Lattice structures

Lattice structures

Applying a lattice pattern is a great way to optimize an existing design.

Lattice structures can create lightweight parts, maximize the surface area of heat exchangers, or improve the printability and reduce the manufacturing cost of an existing design.

Design Metal 3D printing for Topology optimization

Topology optimization

Simulation-driven topology optimization aids in the creation of structures with minimal mass and maximal stiffness.

In topology optimization, the user-defined design space and the load cases are analyzed to determine the areas from which material can be removed. The result of the simulation can then be used to design parts for optimal performance for these loading scenarios.

Design Metal 3D printing for Generative design

Generative design

Generative design is a variation of the simulation-driven topology optimization process.

In generative design, instead of a single output, the analysis produces multiple design candidates. The resulting designs are all manufacturable and fulfill the design requirements. This way, the designer can explore different solutions and select the one that fits the application (for example, based on secondary trade-offs).

It is highly recommended to use one of these advanced CAD techniques - especially when designing parts DMLS/SLM. Below we collected a short list of CAD packages that offer design optimization tools for metal 3D printing to get you started:

Altair Inspire

Powerful topology optimization software with a long history with multiple simulation-driven design tools lattice structure functionality.

Design Metal 3D printing for Altair Inspire

Autodesk Fusion 360

All inclusive and powerful CAD, CAM and simulation software with Generative Design tools for 3D printing and CNC machining.

Design Metal 3D printing for Autodesk Fusion 360

nTopology Element

Professional design and optimization software with advanced lattice capabilities.

Design Metal 3D printing for nTopology Element

Design Rules

Even when using advanced CAD tools, you must follow certain design guidelines. These have to do with the basic mechanics of the metal 3D printing processes. Here is a list of the most important design rules:

Design Metal 3D printing for Minimum Wall thickness

Minimum Wall thickness

DMLS/SLM: 0.4 mm
Binder Jetting: 1.0 mm
Metal Extrusion: 1.0 mm

Binder Jetting & Metal Extrusion parts in the “green” state are fragile. Thicker wall sections reduce the probabillity of breaking.

Design Metal 3D printing for Maximum aspect ratio

Maximum aspect ratio

DMLS/SLM: 8:1
Binder Jetting: 8:1
Metal Extrusion: 8:1

Extra stability can be added to tall features using support ribs (similar to Injection Molding).

Design Metal 3D printing for Minimum feature size

Minimum feature size

DMLS/SLM: 0.6 mm
Binder Jetting: 2.0 mm
Metal Extrusion: 3.0 mm

Isolated features are more prone to failure during printing or handling than wall sections. For pins, consider using an off-the-self insert instead.

Design Metal 3D printing for Minimum detail size

Minimum detail size

DMLS/SLM: 0.4 mm
Binder Jetting: 0.1 mm
Metal Extrusion: 0.5 mm

The minimum detail depends on the size of the laser, binder droplet or nozzle.

Design Metal 3D printing for Minimum hole diameter

Minimum hole diameter

DMLS/SLM: Ø1.5 mm
Binder Jetting: Ø1.0 mm
Metal Extrusion: Ø1.5 mm

For holes that are not aligned along the build direction, consider using a teardrop shape instead to avoid the need for support.

Design Metal 3D printing for Maximum overhang angle

Maximum overhang angle

DMLS/SLM: 50°
Binder Jetting: N/A
Metal Extrusion: 45°

Additional support might be necessary for sintering in Binder Jetting and Metal Extrusion.

Design Metal 3D printing for Unsupported edges

Unsupported edges

DMLS/SLM: 0.5 mm
Binder Jetting: 20 mm
Metal Extrusion: 0.5 mm

Consider eliminating the overhang by adding a 45° chamfer under the unsupported edges.