Composite Panel Surface Defect Reduction via Release Film

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Solution Overview

Problem

The manufacturing of honeycomb sandwich panels for aircraft and aerospace applications is hindered by surface defects such as pitting, telegraphing, and voids, which require costly and labor-intensive 'fill and fare' remediation steps, increasing material and labor costs and weight.

Innovation Solution

A method involving the use of phenolic and epoxy resin pre-impregnated composite fabrics bonded to a honeycomb core, with a controlled curing process using a biaxially oriented polypropylene release film, minimizing thermal shock and eliminating the need for additional resin and remedial steps, resulting in a smooth, paint-ready surface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If adhesive films are stuck on the surfaces of prepreg laminates to allow them to cure together with the prepreg laminates, then surface defects such as resin blurs are decreased, but weight, material cost and labor cost increase

Engineering Contradiction:

Improvesurface defect reductionVSAvoidpanel weight

Core Design Contradiction:

Manufacturing precisionVSWeight of moving object

Solution Approach 1:

The patent removes the adhesive film layer from the panel structure entirely. Instead of adding adhesive films to prevent resin blurs, the invention uses a mold release agent applied to the mold surface, eliminating the need for adhesive films while maintaining surface quality and reducing weight.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces expensive, weight-bearing adhesive films with a disposable mold release agent that is applied only to the mold surface and does not become part of the panel structure. This eliminates the weight and material cost associated with adhesive films while achieving the same surface quality benefit.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Manufacturing precision

If putty material is spread onto the surface to fill in gaps, pits, and holes in the fill and sand step, then surface defects are filled, but labor and material costs increase along with weight

Engineering Contradiction:

Improvesurface defect fillingVSAvoidmanufacturing cost

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent applies a mold release agent to the mold surface before curing, which prevents resin blurs and surface defects from forming in the first place. This preliminary action eliminates the need for subsequent fill and sand operations, reducing labor and material costs while maintaining surface quality.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent converts the potential harm of resin blurs and surface defects into a benefit by using the mold release agent to prevent their formation. Instead of filling defects after they occur, the release agent ensures a smooth surface is produced directly during curing, eliminating the need for corrective operations.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Manufacturing precision

If peel ply materials are used to provide smooth surface to the panel, then surface quality is improved, but weight and manufacturing time increase

Engineering Contradiction:

Improvesurface smoothnessVSAvoidmanufacturing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent removes the peel ply material from the panel structure. Instead of using peel ply to achieve surface smoothness, the invention uses a mold release agent applied to the mold surface, eliminating the need for peel ply and reducing manufacturing time while maintaining surface quality.

Inventive Principle:

Principle #2Taking out (Extraction)

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 significantly reduces material and labor costs, eliminates the need for 'fill and fare' operations, and produces panels with minimal defects, ready for painting without additional processing, thereby saving time and resources.

Implementation Method 1

processing a phenolic and epoxy resin pre-impregnated composite fabric to bond to a honeycomb core

Methodology Applied

Scientific EffectCuring: Chemical Bonding

Implementation Method 2

controlled curing process using a biaxially oriented polypropylene release film, minimizing thermal shock

Methodology Applied

Scientific EffectThermal shock: Thermal Shock

Data Source

PatentUS11833798B2Panel with paint ready surface

Publication Date: 2023.12.05 BE AEROSPACE INC

AI summary

In a preferred embodiment, a composite panel with a smooth outer surface, ready for painting with or without addition of primer, may be created by constructing a panel layup assembly upon a mold, the panel layup assembly including a composite panel having a core and a resin formulation, and a release film between the mold and the composite panel, where a smooth release surface of the release film is in contact with the composite panel upon construction; initiating curing of the composite panel at a first temperature within a lowermost ten percent of a curing temperature range of the resin formulation; continuing curing of the composite panel at a second temperature above the lowermost ten percent of the curing temperature range; and completing curing of the composite panel at a third temperature below the second temperature.