Machinable Composite Mold Using Random Fiber Chips
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Solution Overview
Problem
Composite molds used in forming composite structures are difficult to machine or repair, leading to challenges in achieving tight surface tolerances and maintaining vacuum integrity, as machining exposes heavier weight woven materials and can cause distortion and porosity issues.
Innovation Solution
The use of a quasi-isotropic material composed of randomly oriented fiber bundles or chips impregnated with resin allows for machining to achieve surface tolerances comparable to metal molds, enabling modification and repair of composite molds by adding and machining additional layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If traditional steel alloy molds are used, then strength and temperature resistance are improved, but weight and cost increase, and cycle time increases due to heating and cooling requirements
Solution Approach 1:
The patent applies composite materials consisting of randomly oriented fiber bundles or chips impregnated with resin to manufacture mold bodies. This composite structure provides sufficient strength for mold applications while significantly reducing weight compared to traditional steel alloy molds, directly resolving the contradiction between strength and weight.
2Weight of moving object
If traditional woven fabric composite molds are used, then weight is reduced compared to steel molds, but machining difficulty increases and vacuum integrity is compromised
Solution Approach 1:
The patent changes the fundamental parameter of fiber orientation from structured woven patterns to random orientation. This parameter change transforms the material's machining characteristics, allowing composite molds to be machined with the same ease as metal molds while maintaining vacuum integrity, as the random fiber structure prevents the porosity and distortion issues associated with machining woven fabrics.
3Manufacturing precision
If machining is performed on woven fabric composite molds, then surface modifications are possible, but vacuum integrity deteriorates and dimensional stability is compromised
Solution Approach 1:
The patent changes the fiber orientation parameter from woven to random, which fundamentally alters the material's response to machining. The random fiber structure eliminates the layered structure of woven fabrics, preventing interlaminar shear planes and porosity exposure during machining. This allows achievement of tight surface tolerances comparable to metal molds without compromising vacuum integrity or dimensional stability.
4Strength
If heavily woven fabric is used to build laminate bulk for mold strength, then strength is improved, but surface quality deteriorates due to texture transfer
Solution Approach 1:
The patent applies local quality by using random fiber orientation throughout the entire mold body, which eliminates the need for separate surface and bulk layers. The random structure provides uniform properties throughout, ensuring both structural strength and smooth surface quality simultaneously, unlike woven fabrics that require careful layer selection and orientation to balance these competing requirements.
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 allows for the creation of composite molds that can be machined to achieve surface tolerances similar to metal molds, reducing cycle time and maintaining vacuum integrity, while being lighter and easier to machine than traditional steel alloy molds.
Implementation Method 1
a quasi-isotropic material that is made up of a plurality of randomly oriented fiber bundles or chips that are impregnated with a resin
Data Source
AI summary
Machinable composite molds for use in making a composite structure. The mold includes a mold body having a tool surface that is shaped to provide the molded surface of the composite structure. The mold body is made up of at least one mold layer composed of a quasi-isotropic material composed of a plurality of randomly oriented fiber bundles or chips impregnated with a resin. The use of randomly oriented fiber chips allows post-cure machining of the mold body.