Resin Transfer Molding Control for Composite Race-Track Prevention
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Solution Overview
Problem
Fiber-reinforced polymer composite panels often suffer from defects such as voids and uneven fiber density due to incorrect sizing or misplacement of fiber preforms during resin transfer molding, leading to porosity, resin race tracks, and inconsistent part quality.
Innovation Solution
The introduction of a metered injection of chopped fibers or a variable-volume shim into the gap between the fiber preform and the mold tool face helps eliminate unwanted voids, ensuring a smooth transition in thickness and reducing resin race tracks, while a programmable electronic control unit manages the resin injection and air evacuation to prevent defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If fiber preform is placed in mold cavity, then composite part can be formed, but voids and air gaps may form between preform and tool face causing defects
Solution Approach 1:
The system performs preliminary detection of voids between the preform and tool face before resin injection, and pre-fills these voids with filler material to prevent defect formation during the molding process
Solution Approach 2:
A filler material is introduced as an intermediary substance between the preform and tool face to eliminate air gaps and prevent void formation, acting as a mediator that resolves the interface problem
2Productivity
If resin is injected at high pressure to fill mold cavity, then resin flow is improved, but resin race tracks and uneven fiber density occur
Solution Approach 1:
The system pre-identifies and fills potential race track regions with filler material before resin injection, preventing the harmful rapid resin flow paths from forming during the high-pressure injection process
Solution Approach 2:
The filler material is placed in advance in regions prone to race tracking to counteract and prevent the formation of unwanted resin flow paths before the harmful effect can occur
3Ease of manufacture
If fiber preform placement is not precise, then manufacturing complexity is reduced, but part quality and consistency deteriorate
Solution Approach 1:
The system provides self-correction by automatically detecting voids caused by imprecise preform placement and filling them with filler material, allowing the process to compensate for placement errors without requiring high precision operation
Solution Approach 2:
The system uses sensors to detect the presence and position of the preform, identifies void regions, and automatically adjusts by filling these regions, creating a feedback loop that maintains part quality regardless of initial placement precision
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
This approach enhances part quality by minimizing porosity and resin race tracks, reducing material waste, and improving the consistency of fiber-reinforced polymer panels, allowing for lighter and stronger structures with reduced sensitivity to preform placement and material variations.
Implementation Method 1
introducing a filler into one or more voids between the fiber-based preform and a tool face or faces of one of both mold segments to thereby eliminate any unwanted resin race tracks
Implementation Method 2
transmitting, via the system ECU to the primary vent(s), one or more command signals to evacuate air from the mold cavity
Implementation Method 3
Many RTM processes use a hydrostatic injection system to introduce high-pressure, low-viscosity resin into a closed mold
Implementation Method 4
The mold may be heated and placed under vacuum, as in vacuum assisted resin transfer molding (VARTM), to assist with resin flow
Implementation Method 5
The mold may be heated and placed under vacuum, as in vacuum assisted resin transfer molding (VARTM), to assist with resin flow
Data Source
AI summary
Presented are manufacturing control systems for fabricating composite-material structures, methods for making/operating such systems, and resin transfer molding techniques for ameliorating race-tracking effects in fiber-reinforced polymer panels. A method for forming a composite-material construction includes confirming, via a system electronic control unit (ECU), that a fiber-based preform is placed in a mold cavity and that opposing mold segments of the molding apparatus are sealed together. A filler, such as a compressible bladder, a cluster of spring-biased pins, or a spray-chopped fiber bed, is introduced into a void between the fiber-based preform and a tool face of one mold segment to thereby eliminate an unwanted resin race track. The system ECU commands a resin pump to inject resin through a primary gate of the molding apparatus and into the mold cavity to thereby impregnate the fiber-based preform with the resin. One or more vents operate to evacuate air from the mold.