Introduction
3D printing with HP Multi Jet Fusion (MJF) technology offers a blend of high precision and superior aesthetics, making it a popular choice in various industries. Understanding the key design considerations for optimizing the appearance and finish of MJF prints is essential for achieving the best results.
Minimizing the Visibility of Layer Lines:
MJF technology uses 80 µm layers, which are typically not visible to the naked eye. However, for parts with small angles, layering steps can become noticeable. To minimize the stair-stepping effect, it’s recommended to keep angles above 20° between large flat areas and the XY plane for upward-facing surfaces. For downward-facing surfaces, ensure they avoid angles less than 5° to 10°. Experimenting with orientations can lead to the best look and feel for each application.
MJF Aesthetic Guidelines:
- Feature Placement: Place small features with critical dimensions, like pins, holes, and raised texts, in the same plane to ensure uniformity and precision. Downward-facing areas typically have a better appearance.
- Smooth Cross-Section Transition: Design parts with gradual transitions to avoid stress concentrations and improve structural integrity.
- Lightweight Designs: Implement internal lattices or hollow parts for weight reduction without compromising strength.
- Aspect Ratio Management: Avoid designing long, thin, flat parts with an aspect ratio higher than 10:1 to prevent warping and maintain aesthetic quality.
- Curved Segment Design: Be cautious with predominantly long and thin curved segments, as they may pose challenges in printing and maintaining structural stability.
- Avoiding Ridges and Ribs: On large flat areas, avoid ridges and ribs to maintain even surfaces and reduce the risk of print failures.
Design for Efficient Cleaning:
Ease of cleaning is a notable advantage of MJF technology. Add at least two drain holes on opposite faces for hollow parts to enable efficient powder removal. The recommended minimum diameter for drain holes is 5 mm. In parts with lattice structures, consider leaving the powder trapped inside or partially opening the lattice. The minimum gap in a lattice structure to ensure material removal is 5 mm. For narrow ducts, design a strip or chain that can be pulled out after printing to dislodge most of the material.
Advanced Cleaning Techniques:
For ducts narrower than 5 mm, cleaning the inside with a flexible screw after printing is recommended. To enhance the cleaning performance, attach the flexible screw to a drill. This approach ensures that even the most intricate and narrow spaces within MJF prints are thoroughly cleaned, maintaining the aesthetic and functional integrity of the part.
Conclusion
Designing for MJF technology requires a meticulous approach to aesthetics, feature placement, and post-processing. By following these guidelines, designers can create 3D-printed parts that not only meet functional requirements but also exhibit excellent surface finish and detail. Embracing these practices will lead to superior quality prints that fully capitalize on the capabilities of HP Multi Jet Fusion.
