Design Principles for AM Production

DFAM is not just about making a design printable; it's about revolutionizing the design approach to harness the full potential of additive manufacturing. By overcoming traditional design constraints and fully embracing the capabilities of AM, designers can create innovative, efficient, and optimized products.

• Overcoming Traditional Design Constraints/Mindset:

  • Traditional Limitations: Conventional manufacturing methods like casting, machining, or injection molding come with their inherent design constraints. Angles, undercuts, and internal structures, for example, can present significant challenges.

  • Redefining Design with AM: AM offers unparalleled design freedom. Features that are difficult or even impossible with traditional methods can be easily realized using AM. Designers need to let go of the older mindset bound by these constraints and approach design with a fresh perspective, tailored to the potential of AM.

  • Case in Point: Lattice structures, which are often impossible or too costly to manufacture traditionally, can be directly printed using AM, offering lightweight yet strong components suitable for various applications.

• "Leaning In" to Additive Design Possibilities - "Think Additive First":

  • Description: Embracing the full potential of AM involves not just understanding its capabilities but also actively leveraging them in the design process.

  • Benefit-Centric Design: Instead of asking, "Can this be printed?", the mindset should shift to, "How can I design this to maximize the benefits of AM?". This involves utilizing the unique capabilities of AM to enhance functionality, reduce weight, or improve efficiency.

  • Holistic Approach: From topology optimization (designing parts based on stress requirements) to multi-material printing (combining different materials in a single print for enhanced properties), there's a multitude of ways AM can influence design choices. Designers should aim to incorporate these aspects from the inception of the design process.

  • Iterative Prototyping: One of the advantages of AM is rapid prototyping. Designers can quickly iterate, test, and refine their designs, ensuring that the final product is optimized for both performance and manufacturability.

While AM offers designers an expanded realm of possibilities, it's essential to be cognizant of the unique challenges posed by the technology. By understanding and designing with these constraints in mind, one can harness the full potential of AM while ensuring successful and high-quality outcomes.

• Self-Supporting Angles & Overhangs:

  • Description: One of the most common constraints in AM is the requirement for self-supporting angles. When designing parts, angles that are too shallow relative to the build plate can lead to print failures because they lack adequate support during the printing process.

  • Typical Values: Depending on the specific AM process and material, self-supporting angles usually range from 45° to 65° from the horizontal. Anything steeper than this typically requires support structures to ensure proper formation.

  • Implications: Implementing support structures can lead to additional post-processing work, as these supports will need to be removed after printing. Moreover, the point where the support meets the part can sometimes have a slightly different surface finish, which may need further treatment.

• Internal Channels & Hollow Structures:

  • Description: AM allows for the design of internal channels and hollow structures, which can be advantageous for weight-saving or functionality. However, these internal structures can pose challenges if they trap uncured material or support material inside.

  • Considerations: For processes like SLA, where liquid resin is cured layer by layer, internal cavities need to be designed with escape holes or drainage points to ensure no uncured resin remains trapped inside.

• Minimum Feature Size & Wall Thickness:

  • Description: The resolution of the AM machine determines the smallest feature size it can print, and there are practical limits to how thin a wall or a feature can be while still maintaining structural integrity.

  • Guidelines: It's essential to refer to the specific machine's and material's guidelines to ensure features aren't too small or walls too thin. This ensures the part's durability and successful printing without deformities.

• Thermal Distortions:

  • Description: Processes like FDM (Fused Deposition Modeling) and SLM (Selective Laser Melting) involve the heating of material. As these materials cool, they can contract, leading to warping or internal stresses.

  • Mitigation: Proper design considerations, like uniform wall thickness and strategic placement of parts on the build plate, can help reduce these thermal effects. Additionally, some AM machines offer controlled cooling environments to minimize distortions.

Creating assemblies using additive manufacturing presents unique opportunities and challenges. Designing specifically for AM assemblies can streamline post-production, improve fitment, and ensure functionality.

• Use of Standard Hardware/Inserts within 3D Printed Parts:

  • Description: Integrating standard hardware, like nuts, bolts, or threaded inserts, within 3D printed parts can enhance the part's functionality and durability.

  • Enhanced Strength: Metal inserts can provide superior strength in comparison to printed threads, ideal for load-bearing applications.

  • Reusability: They allow for repeated assembly and disassembly without wearing out the part.

  • Design Considerations: It's essential to design appropriate cavities or recesses in the part to accommodate these inserts. Post-printing methods, like heat-staking or ultrasonic insertion, can be used to embed these components.

• Understanding AM-Specific Tolerances:

  • Description: AM processes have unique tolerances depending on factors like material, print orientation, and machine calibration.

  • Implications: Parts designed without considering these tolerances may not fit together as intended, leading to assembly challenges.

  • Guidelines: It's crucial to understand and work within the specific tolerance capabilities of the chosen AM process. Building in allowances for post-processing or fitment adjustments can also be beneficial.

• Designing for (Reduced) Post-Processing and Assembly:

  • Description: The way parts are designed for AM can influence the amount of post-processing required.

  • Integrated Features: Incorporating features like snap-fits, dovetail joints, or interlocking mechanisms can reduce the need for external hardware and simplify assembly.

  • Orientation Consideration: Designing parts with their assembly orientation in mind can minimize the need for supports, reducing post-print cleanup.

  • Benefits: Reducing post-processing saves time, reduces costs, and can result in cleaner, more efficient assemblies.

• Fitment with Additive Parts to Non-Additive Components:

  • Description: Often, AM components need to interface with traditionally manufactured parts. Ensuring proper fitment is crucial for functional assemblies.

  • Challenges: Non-additive components may have different tolerances, surface finishes, or material properties that can influence fitment.

  • Hybrid Prototyping: Test-fit AM components with their non-additive counterparts early in the design process to identify and rectify fitment issues.

  • Adaptive Design: Design AM parts with adjustment features or allowances to accommodate discrepancies that might arise during assembly.