Composite Injection Molding Pressure Control
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Solution Overview
Problem
Injection molding of composite material parts in aviation often results in pores due to gas bubbles formed during resin curing, which weaken the parts and require scrapping.
Innovation Solution
Applying pressure inside the mold during resin curing, before the resin reaches a critical curing value of 20-30%, using a fluid under pressure injected through multiple points to prevent bubble formation, ensuring uniform high pressure and avoiding gas bubbles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If resin is injected into the mold to impregnate the preform, then the composite part is formed, but gas bubbles are generated during curing which create pores and weaken the part
Solution Approach 1:
Pressure is applied to the resin and preform before the resin reaches the critical curing value (20-30%), when the resin is still sufficiently fluid. This preliminary pressurization prevents gas bubbles from forming or becoming trapped in the preform, thereby avoiding pore formation and maintaining part strength without requiring post-processing scrapping
2Manufacturing precision
If pressure is applied to prevent gas bubbles during curing, then pore formation is avoided, but the resin must be pressurized at a specific curing stage before it becomes too viscous
Solution Approach 1:
The method monitors the curing progress of the resin and applies pressure based on the critical curing value threshold (20-30%). By detecting when the resin reaches this critical stage, the system activates pressurization at the optimal moment, ensuring uniform pressure distribution throughout the mold while capturing the limited time window before the resin becomes too viscous for effective pressurization
3Manufacturing precision
If pressure is applied after resin injection to prevent bubbles, then pore formation is reduced, but the resin viscosity increases during curing making uniform pressure application difficult
Solution Approach 1:
Pressure application is initiated before the resin reaches the critical curing value of 20-30%, when the resin is still in a sufficiently fluid state. This timing ensures that the resin can flow and redistribute uniformly under pressure, allowing effective elimination of gas bubbles and prevention of pore formation throughout the entire part volume
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 method effectively prevents pore formation in composite material parts, ensuring a strong and bubble-free structure by maintaining pressure until the resin is fully cured, even with volatile resins and solvents.
Implementation Method 1
injecting a resin into the mold so as to impregnate the preform, and then in unmolding the part after the resin has cured
Implementation Method 2
subjecting the resin and the preform to pressure inside the mold while the resin is curing
Data Source
AI summary
A method of injection molding a part made of composite material is provided. The method includes placing a preform in a mold; injecting a resin into the mold so as to impregnate the preform; unmolding the part after curing the resin; and subjecting the resin and the preform to pressure inside the mold while the resin is curing.