Chopped Fiber Infusion Printing

Chopped Fiber Infusion Printing builds a chopped-fiber composite preform additively, then infuses resin to increase stiffness, strength, and sealing versus as-printed parts.

Overview

Chopped Fiber Infusion Printing produces composite parts by 3D printing a chopped-fiber reinforced polymer structure, then infusing it with a low-viscosity resin to fill porosity and lock in the fiber-rich matrix. The infusion step boosts stiffness and compressive strength, improves surface sealing, and can reduce print-time sensitivity to internal voids compared to printing a fully solid part.

Choose it for lightweight structural parts where you need better mechanical performance than standard chopped-fiber FFF and you can tolerate a secondary infusion/cure process. Expect tradeoffs: dimensional change from infusion and cure shrink, cosmetic variability, and process controls (resin mix, temperature, vacuum/pressure, cure schedule) that drive repeatability. Tight tolerances usually require machining critical interfaces after cure.

Common Materials

  • Carbon fiber nylon
  • Glass fiber nylon
  • Carbon fiber PETG
  • Epoxy resin
  • Polyurethane resin

Tolerances

±0.010"

Applications

  • Lightweight machine brackets
  • Robot end-effector bodies
  • Drone airframe components
  • Custom fixtures and nests
  • Protective housings for field equipment
  • Automotive prototype mounts

When to Choose Chopped Fiber Infusion Printing

Pick this process for low-to-medium volume composite parts that need higher stiffness and better sealing than typical chopped-fiber printed plastics. It fits parts with moderate dimensional requirements and clear load paths where you can post-machine critical datums after cure. It’s most effective when the design can accommodate resin flow paths and predictable cure behavior.

vs Continuous Fiber FDM

Choose chopped fiber infusion printing when you need more isotropic reinforcement and don’t want to design around continuous-fiber toolpaths and layer-by-layer fiber placement limits. It also works well for thicker, bulkier parts where infusion improves through-thickness properties, while continuous fiber excels at highly directional strength along placed fiber lines.

vs Standard FDM (unfilled thermoplastic)

Choose chopped fiber infusion printing when the part is load-bearing and you need a step-change in stiffness and creep resistance over unfilled prints. The infusion step can also seal porosity for parts exposed to oils, moisture, or washdown where raw FDM would wick or leak.

vs CNC machining (plastic or aluminum)

Choose chopped fiber infusion printing when geometry drives cost in machining (deep pockets, internal features, rapid iterations) and you can accept additive-level tolerances with post-machining only on interfaces. It’s a good fit when weight reduction and composite stiffness matter more than tight, all-over dimensional control.

vs SLS Nylon (PA12/PA11)

Choose chopped fiber infusion printing when you need higher stiffness than SLS nylon and want improved sealing without heavy coatings. SLS typically wins on uniformity, fine detail, and batch scalability; infusion printing wins when structural performance is the priority and secondary processing is acceptable.

Design Considerations

  • Provide intentional resin flow paths (vent/drain holes, channels, or porous regions) so infusion reaches all critical sections
  • Avoid fully enclosed voids that can trap air and block resin; add access features for vacuum/pressure and bleed-out
  • Add machining stock on critical datums and interfaces, and call out which surfaces will be post-machined
  • Keep wall thicknesses consistent where possible to reduce uneven cure shrink and local distortion
  • Define resin system and cure requirements on the print (epoxy vs polyurethane, Tg target, post-cure temperature)
  • Orient primary load paths to minimize interlayer peel and place ribs/webs where infusion can reinforce through-thickness