Resin-Infiltrated FFF Composite Parts for Stronger Z-Axis Bonding

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Solution Overview

Problem

3D printed composite parts using fused filament fabrication (FFF) exhibit anisotropic properties and poor Z-direction strength, and thermoset-based FFF printing is limited by part shrinkage and dimensional accuracy issues, preventing widespread adoption.

Innovation Solution

Infiltrate 3D printed parts with a resin, such as a thermoset resin, using continuous fiber reinforcement in the Z-direction and X-Y plane, allowing for improved mechanical properties and isotropic behavior by bonding the reinforcement with the thermoplastic FFF part.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If thermoset-based FFF printing is used, then mechanical properties and thermal stability are improved, but part shrinkage and dimensional accuracy issues occur

Engineering Contradiction:

Improvemechanical propertiesVSAvoiddimensional accuracy

Core Design Contradiction:

StrengthVSManufacturing precision

Solution Approach 1:

The part is divided into a thermoplastic FFF-printed skeleton structure and thermoset resin-infused regions. The thermoplastic skeleton provides dimensional stability during printing, while the thermoset resin is subsequently infused to provide enhanced mechanical properties and thermal stability, effectively separating the conflicting requirements of dimensional accuracy and mechanical performance.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention creates a composite structure combining thermoplastic FFF-printed materials with thermoset resin. This composite approach allows the thermoplastic component to ensure dimensional accuracy during fabrication while the thermoset component provides superior mechanical properties and thermal stability, resolving the contradiction between manufacturing precision and mechanical strength.

Inventive Principle:

Principle #40Composite materials

2Strength

If continuous fiber reinforcement is added in Z-direction, then Z-direction strength is improved, but device complexity and manufacturing process complexity increase

Engineering Contradiction:

ImproveZ-direction strengthVSAvoidmanufacturing process complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention merges continuous fiber reinforcement with the resin infusion process. Fibers are placed within the build chamber and become integrated with the thermoset resin during infiltration, creating a unified composite structure that enhances Z-direction strength without requiring separate, complex fiber placement equipment or multi-step manufacturing processes.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The resin infusion process automatically impregnates the continuous fibers with thermoset resin, creating strong bonding between the reinforcement and the FFF-printed skeleton. This self-service mechanism eliminates the need for additional bonding steps or complex equipment, as the resin itself serves as both the matrix and the bonding agent.

Inventive Principle:

Principle #25Self-service

3Strength

If resin infiltration is performed, then mechanical properties and isotropic behavior are improved, but manufacturing time and process complexity increase

Engineering Contradiction:

Improvemechanical propertiesVSAvoidmanufacturing time

Core Design Contradiction:

StrengthVSLoss of time

Solution Approach 1:

The FFF-printed skeleton is fabricated first with built-in channels and pathways designed for subsequent resin infiltration. This preliminary action includes designing the infill patterns and internal geometry to facilitate easy resin flow and uniform distribution, thereby reducing the complexity and time required for the infiltration step while ensuring consistent mechanical properties throughout the part.

Inventive Principle:

Principle #10Preliminary action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enhances Z-direction strength, reduces warping, and maintains dimensional accuracy while providing tunable mechanical properties and thermal stability, enabling larger part production without thermal runaway.

Implementation Method 1

infiltrating the printed part using a resin delivered to an interior of the part via the at least one inlet to surround the infill pattern with the resin

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

allowing the infiltrated resin to cure

Methodology Applied

Scientific EffectPolymerization: Photopolymerisation

Data Source

PatentUS12539664B2Thermoset injection into fused filament fabrication parts with discontinuous and/or continuous reinforcement

Publication Date: 2026.02.03 MARKFORGED INC

AI summary

Methods of infiltrating a three-dimensional part with a resin are disclosed. The methods include designing a part to be printed, the part having at least one inlet and an infill pattern. The methods include using three-dimensional printing to print the designed part. The methods further include infiltrating the printed part using a resin delivered to an interior of the part via the at least one inlet to surround the infill pattern with the resin. The methods additionally include allowing the infiltrated resin to cure.