Co-nested Cavity Mold for High Fiber Loading Composites
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Solution Overview
Problem
Existing methods for forming thermoplastic composite articles with high volume fiber loading face challenges such as air pockets, voids, and difficulty in achieving uniform resin wetting and strong parts, particularly in injection and compression molding processes.
Innovation Solution
A method involving a co-nested cavity mold design where thermoplastic composite material with at least 40% long fiber reinforcement is heated and pressed in a first mold cavity, then the material flows into a second cavity under pressure, allowing for high volume fiber loading and efficient formation of strong, uniform composite articles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional injection molding or compression molding is used to achieve high volume fiber loading (above 40%), then fiber content can be increased, but air pockets and voids form and resin wetting becomes non-uniform
Solution Approach 1:
The mold is divided into two separate sections: a first mold section for heating and initial compression, and a second mold section for final forming. This segmentation allows the material to be processed in stages, first achieving high fiber loading in the first section, then transferring to the second section for uniform wetting and detailed feature formation, thereby resolving the contradiction between high fiber content and uniform resin distribution.
Solution Approach 2:
The first mold section performs preliminary heating and compression of the thermoplastic composite material to achieve high fiber loading and remove air pockets before the material is transferred to the second mold section. This preliminary action ensures that the material is properly prepared and degassed, enabling uniform resin wetting in the subsequent forming stage.
2Strength
If high volume fiber loading (above 40%) is achieved in thermoplastic composite material, then fiber reinforcement is improved, but material flowability deteriorates
Solution Approach 1:
The forming process is segmented into two distinct mold sections with different functions. The first section provides high compression for fiber loading without requiring material flow, while the second section handles the flowing and shaping of material. This segmentation decouples the conflicting requirements of high fiber loading and material flowability.
Solution Approach 2:
The process utilizes temperature and pressure parameter changes between the two mold sections. The first section operates at high temperature and pressure to achieve fiber loading, then the material is transferred to the second section where parameters are adjusted to enable proper flowing and wetting. This parameter control allows high fiber content while maintaining flowability where needed.
3Manufacturing precision
If detailed features are formed in high fiber loading composites, then product functionality is improved, but manufacturing complexity increases
Solution Approach 1:
The mold is segmented into two sections with specialized functions: the first section handles high fiber loading compression, while the second section is designed with detailed cavities for forming complex features. This segmentation allows each section to be optimized for its specific function, achieving detailed feature formation without excessive overall complexity.
Solution Approach 2:
The first mold section is positioned within or adjacent to the second mold section, with the outlet of the first section communicating with the inlet of the second section. This nested or integrated configuration allows the two-stage process to occur in a compact arrangement, reducing manufacturing complexity while enabling detailed feature formation in high fiber loading composites.
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 enables the production of thermoplastic composite articles with high volume fiber loading, overcoming flowability issues and achieving strong, uniform parts with detailed configurations, exceeding traditional injection molding limits of 30-40% fiber volume.
Implementation Method 1
applying heat and pressure to the first thermoplastic composite material in the first mold cavity until the first mold section reaches at least a first process temperature
Implementation Method 2
wherein said cooling solidifies the first thermoplastic composite to form a molded article having the shape of the second mold cavity
Data Source
Figure 1~1a
Figure 2
Figure 3
AI summary
An apparatus for forming a thermoplastic article having long fiber reinforcement, wherein the apparatus comprises (a) at least one mold body (20) having at least one first mold section (22) configured for defining a first mold cavity (30), the at least one first mold section having an inlet (26) and an outlet (28) and at least one second mold section (24) including two or more fitting surfaces (35) which come together using one or more second mold section pieces (33) to define a second mold cavity (36), the second mold section (24) having an inlet (38), wherein the outlet (28) of the first mold section (22) is in communication with the inlet (38) of the second mold section (24) via at least one flow port (40), and the second mold cavity (36) has a configuration for forming the article; (b) a piston (34) configured so as to be able to enter the first mold cavity (30); and (c) at least one press (42) capable of heating and cooling the mold body (20) and the mold sections (22, 24).