Design Guidelines
Optimize your CAD models for manufacturing. Follow these rules to ensure your parts come out strong, accurate, and cost-effective.
Introduction and Objective
This document serves as the official technical standard for parts manufactured by YVR 3D. Unlike subtractive manufacturing (CNC) or formative manufacturing (Injection Molding), Additive Manufacturing (AM) builds geometry layer-by-layer. This process introduces specific anisotropic properties, thermal shrinkage behaviors, and geometric constraints.
The objective of this guide is to outline the Design for Additive Manufacturing (DfAM) principles required to achieve optimal dimensional accuracy, mechanical strength, and manufacturing feasibility using our industrial FDM fleet.
File Formats
We strongly recommend STEP files over STL. STEP files store geometry as NURBS (true curves), resulting in perfectly circular holes and superior surface finish.
Design Tips
- STL: If used, set chord height to 0.005mm.
- Ensure meshes are 'Watertight' (Manifold).
- Check surface normals point outward.
Wall Thickness
Walls thinner than 0.8mm result in a single perimeter loop (0.4mm nozzle), which lacks structural integrity. Structural walls allow for 'infill overlap', significantly increasing tensile strength.
Design Tips
- Design in multiples of 0.4mm (nozzle size).
- Avoid abrupt thickness transitions to prevent warping.
- Structural parts should target 2.0mm+.
Overhangs & Supports
Angles >45° require sacrificial support structures, which leave rough surface marks. Horizontal spans up to 15mm can be 'bridged' without support, though minor sagging is expected.
Design Tips
- Use Chamfers (45°) instead of Fillets (Radii) on bottom edges.
- Chamfers eliminate the need for supports.
- Orient critical faces upwards to avoid support scarring.
Text & Micro-Features
XY resolution is limited by the 0.42mm bead width. Serif fonts (like Times New Roman) have thin tails that fail to resolve.
Design Tips
- Use Bold, Sans-Serif fonts (Arial, Helvetica).
- Embossed Height: Min 0.6mm.
- Engraved Depth: Min 0.4mm.
Tolerances & Fitment
Plastics shrink as they cool. A 'perfect' CAD fit will be an interference fit in reality. You must design clearance gaps.
Design Tips
- Free Running Fit (Hinges): 0.3mm clearance.
- Locational Fit (Lids): 0.2mm clearance.
- Screw Holes: Oversize by +0.2mm (e.g., Ø3.2mm for M3).
Threading Strategy
Directly printing threads smaller than M6 is discouraged due to resolution limits. Brass Heat-Set Inserts offer superior pull-out strength.
Design Tips
- Design tapered holes for inserts.
- Captive Nuts: Use hexagonal slots.
- Self-Tapping: Undersize hole by 0.2mm (PLA only).
Structural Anisotropy
FDM parts are like wood grain; they split easily across the layers (Z-axis). Tensile strength is highest along the filament strands.
Design Tips
- Orient bolts to compress layers, not pull them apart.
- Print tall, thin features lying flat on the bed.