Prepreg Curing Process for Composite Surface Finish

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The high cost and equipment requirements of autoclave processing for large composite parts limit the widespread use of prepreg technology, as it necessitates large and expensive autoclaves, and existing methods face challenges with fiber consolidation, cure shrinkage, and surface finish quality.

Innovation Solution

A process involving reduced pressure and multiple temperature stages for curing prepregs, which includes initial volatile material removal, curing, and optional secondary temperature exposure to enhance consolidation and reduce voids and stress, using thermosetting resin compositions with specific viscosity and component ranges.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If autoclave processing is used to achieve smooth surface finish and high fiber consolidation, then composite quality is improved, but equipment cost and processing expense increase significantly

Engineering Contradiction:

Improvesurface finish qualityVSAvoidequipment cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent replaces the expensive, reusable autoclave equipment with a disposable vacuum bag system. The vacuum bag is a low-cost, single-use component that provides the necessary sealing and vacuum function without requiring investment in million-dollar autoclave equipment. This allows smooth surface finish and good fiber consolidation to be achieved through a simple vacuum bagging process rather than expensive autoclave processing.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent substitutes the mechanical autoclave system (which uses controlled temperature and pressure) with a simpler vacuum-based system. By using vacuum pressure differential instead of mechanical compression, the process achieves similar consolidation and surface quality outcomes without the complex mechanical infrastructure of an autoclave.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Volume of moving object

If large autoclaves are used to manufacture large composite parts, then part size capability is improved, but equipment investment and processing cost increase

Engineering Contradiction:

Improvepart size capabilityVSAvoidequipment investment

Core Design Contradiction:

Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent enables large parts to be manufactured by dividing the curing process into manageable segments using modular vacuum bagging systems. Rather than requiring a single large autoclave, the vacuum bagging method can be applied to large parts using appropriately sized bags and support structures, allowing large-scale production with smaller, more affordable equipment.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The vacuum bag serves as a disposable, low-cost alternative to expensive large autoclaves. By using a simple vacuum seal around the part rather than enclosing it in a massive pressure vessel, the process achieves large part capability without the prohibitively expensive equipment investment required for traditional autoclave processing.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Ease of operation

If traditional curing methods are used, then processing simplicity is maintained, but fiber consolidation and void reduction are insufficient

Engineering Contradiction:

Improveprocessing simplicityVSAvoidfiber consolidation

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent applies vacuum pressure before and during the curing process to pre-consolidate the fiber layers and remove air pockets and volatiles. This preliminary consolidation action, performed while the resin is still relatively fluid, ensures excellent fiber packing and void-free structures before the resin fully cures, achieving high manufacturing precision while maintaining operational simplicity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent utilizes the phase transition of volatiles and air pockets from gas to vacuum-evacuated state during curing. By applying vacuum during the resin's liquid phase, the process removes trapped gases and volatiles, allowing complete resin infiltration of fiber layers and achieving superior fiber consolidation and void reduction.

Inventive Principle:

Principle #36Phase transitions

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 process enables efficient curing of large composite parts with improved fiber consolidation, reduced voids, and enhanced surface finish, making prepreg technology more accessible and cost-effective by eliminating the need for large autoclaves.

Implementation Method 1

Exposing the prepreg under reduced pressure to a first elevated temperature for a time sufficient to remove substantially all volatile materials in the prepreg

Methodology Applied

Scientific EffectEvaporation: Evaporation