Yes, fused deposition modeling (FDM) can generate interconnected porous structures. Still, there are some considerations and limitations compared to techniques like Selective Electron Beam Melting (SEBM), Selective Laser Sintering (SLS), or Selective Laser Melting (SLM).

Additive Manufacturing Techniques Overview

**1. SEBM/SLS/SLM:

• Materials: Typically used with metals or ceramics.
• Resolution: Can achieve fine resolutions and high-quality porous structures, often with pore sizes in the range of 100-200 micrometres or smaller.
• Advantages: High precision, ability to create complex geometries with interconnected pores, and excellent material properties.

**2. FDM:

• Materials: Primarily used with thermoplastics such as PLA, ABS, PETG, etc.
• Resolution: It generally has a larger minimum feature size than SEBM/SLS/SLM. Typical resolutions are 100-500 micrometres, depending on the printer and nozzle size.
• Advantages: More accessible and cost-effective compared to high-end techniques like SLM. Suitable for rapid prototyping and less complex geometries.

Using FDM for Porous Structures

**1. Design Considerations:

• Layer Height: FDM’s resolution is affected by layer height, which typically ranges from 50 micrometres to several millimetres. Smaller layer heights can improve resolution but might increase print time.
• Nozzle Size: The diameter of the nozzle also affects the resolution. Smaller nozzles can help achieve finer details.
• Infill Patterns: Adjusting the infill density and pattern can help create porous structures. Common patterns include honeycomb, grid, and gyroid.

**2. Interconnected Porosity:

• Support Structures: Creating interconnected pores requires careful design to ensure the model supports itself during printing. Support structures or soluble supports can help manage complex geometries.
• Custom Slicing Settings: Use slicing software to define custom infill patterns and densities to achieve desired porosity. Software like Cura, PrusaSlicer, or MatterControl can help customize these settings.

**3. Post-Processing:

• Material Removal: In some cases, post-processing techniques such as chemical baths or mechanical milling may further refine the porous structure and improve the quality of interconnected pores.
• Ageing and Conditioning: FDM parts might require ageing or conditioning to reach desired mechanical properties or achieve better porosity.

**4. Limitations:

• Resolution: FDM generally cannot match the fine resolution of SEBM/SLS/SLM techniques. Standard FDM printers may be challenging to use for pores smaller than 100 micrometres.
• Material Properties: Thermoplastics used in FDM may have mechanical properties different from those of metals or ceramics, which could affect the performance of the porous structures.

Practical Tips

• Experimentation: Test different nozzle sizes, layer heights, and infill patterns to find the optimal settings for your specific application.
• Advanced FDM Printers: Some advanced FDM printers offer higher resolutions and more precise control, which may improve your ability to create fine, porous structures.
• Material Choice: Consider using speciality filaments that offer improved mechanical properties or easier processing for your application.

Summary

FDM can be used to create interconnected porous structures, but it typically has limitations compared to SEBM/SLS/SLM regarding resolution and material properties. By optimizing your design, printer settings, and post-processing techniques, you can achieve effective porous structures with FDM, especially for applications where high precision is less critical.