Design for Manufacturing: Essential DFM Tips for 3D Printing

Designing parts for 3D printing differs significantly from designing for CNC machining or injection molding. Following key design for manufacturing (DFM) principles saves time, reduces costs, and ensures successful prints.

Wall Thickness

Minimum wall thickness requirements vary by process:

• SLA: 0.6-1.0mm recommended
• SLS: 0.8-1.5mm recommended
• FDM: 1.0-2.0mm recommended
• Metal DMLS: 0.3-0.5mm (but 0.8mm+ for strength)

Insufficient wall thickness causes warping, breaking, or incomplete printing.

Overhangs and Support Requirements

3D printers cannot print in mid-air. Parts with overhangs exceeding 45 deg typically require support structures:

• 0-45 deg: No supports needed (self-supporting)
• 45-60 deg: May need minimal support
• 60 deg+: Full support structures required

Tip: Orient parts to minimize support usage -- supports leave marks and increase material costs.

Tolerances for Assembly

Typical as-built tolerances for 3D printed parts:

• SLA: +-0.1mm to +-0.3mm
• SLS: +-0.2mm to +-0.5mm
• FDM: +-0.2mm to +-0.5mm

Design clearances accordingly: 0.3mm for loose fit, 0.15mm for snug fit, 0.05mm for tight fit.

Holes and Channels

Design holes with slight oversizing -- 3D printed holes often shrink slightly. For threaded holes, consider using threaded inserts (heat-set inserts) rather than printing threads directly, especially in plastics.

Snap-Fit Design for 3D Printing

Snap-fits are excellent for 3D printed assemblies. Key parameters:

• Beam thickness: 0.8-1.5mm
• Hook angle: 30-45 deg
• Beam length: Keep short for best retention
• Material: Nylon/TPU preferred for flexibility

Embossed and Engraved Text

• Minimum embossed text height: 1.5mm
• Minimum engraved text depth: 0.5mm
• Minimum font size: 10pt bold for readability

Conclusion

Early consideration of 3D printing design rules prevents costly redesigns and failed prints. When in doubt, consult your manufacturer during the design phase -- many offer free DFM reviews.