Topology optimization, lattice structures, design rules for metal 3D printing and more.
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.
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:
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.
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.
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.
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:
Powerful topology optimization software with a long history with multiple simulation-driven design tools lattice structure functionality.
All inclusive and powerful CAD, CAM and simulation software with Generative Design tools for 3D printing and CNC machining.
Professional design and optimization software with advanced lattice capabilities.
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:
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.
Binder Jetting: 8:1
Metal Extrusion: 8:1
Extra stability can be added to tall features using support ribs (similar to Injection Molding).
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.
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.
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.
Binder Jetting: N/A
Metal Extrusion: 45°
Additional support might be necessary for sintering in Binder Jetting and Metal Extrusion.
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.