Oxygen-Controlled 3D Printing for High-Strength Resin Parts
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Solution Overview
Problem
Conventional stereolithography processes for 3D printing fail to produce high-strength plastic articles suitable for physically demanding applications due to limitations in resin curing and hardening.
Innovation Solution
A 3D printing system with a resin vessel, build tray, light engine, and gas handling system that controls oxygen partial pressures in two chambers, using a transparent sheet to prevent resin hardening on the upper surface while accelerating polymerization with a higher oxygen partial pressure in the lower chamber, and employing a photocurable resin with catalysts for ring opening metathesis polymerization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional stereolithography processes are used, then 3D articles can be manufactured, but the articles do not achieve very high strengths required for physically demanding applications
Solution Approach 1:
The patent applies parameter changes by controlling oxygen partial pressure in the resin vessel. Specifically, maintaining low oxygen partial pressure (below 0.2 atmosphere, preferably below 0.1 atmosphere) during polymerization accelerates the curing reaction and produces higher cross-linking density in the resin, resulting in 3D articles with very high strength suitable for demanding applications like gear trains.
2Productivity
If oxygen partial pressure is reduced to accelerate polymerization, then curing speed increases, but resin may harden on the transparent sheet surface
Solution Approach 1:
The patent applies local quality by creating different oxygen partial pressure conditions in different locations. The resin vessel has a gradient where the bulk resin experiences low oxygen partial pressure to accelerate polymerization, while the interface with the transparent sheet maintains higher oxygen concentration to prevent premature hardening and ensure proper adhesion. This spatial variation in oxygen concentration allows both fast curing and good surface quality.
3Strength
If high cross-linking density is achieved for high strength, then article strength increases, but process control becomes more difficult
Solution Approach 1:
The patent applies pneumatics by using a gas handling system to control the oxygen partial pressure in the resin vessel. The system uses gas flow control and pressure regulation to maintain the optimal oxygen environment during polymerization. This pneumatic control approach provides precise and reliable control over the curing process, enabling consistent high-strength articles without excessive complexity.
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
The system produces high modulus and strength 3D articles by controlling oxygen partial pressures and using specific photocurable resins, enabling the creation of high-performance plastic components for demanding applications.
Implementation Method 1
The light engine is configured to transmit modulated radiation up through the transparent sheet to a build plane within the resin above the transparent sheet... operate the light engine to selectively polymerize a layer of the photocurable resin
Implementation Method 2
The greater second partial pressure of oxygen in the lower chamber enables oxygen to diffuse through the transparent sheet to prevent hardening of resin upon the upper surface of the transparent sheet
Implementation Method 3
The controller is configured to operate the gas handling system to reduce and control a partial pressure of oxygen in the upper and lower chambers... The first and second partial pressures are less than an ambient partial pressure of oxygen so as to accelerate or increase polymerization or cross-linking
Data Source
AI summary
A three-dimensional (3D) printing system for manufacturing a 3D article includes a resin vessel, a build tray, a movement mechanism, a light engine, a housing, a gas handling system, and a controller. The resin vessel includes a transparent sheet on a lower side. The housing defines two chambers including an upper chamber and a lower chamber. The upper chamber is in fluidic communication with the resin contained by the resin vessel. The lower chamber is in fluid communication with a lower surface of the transparent sheet. The controller is configured to (a) operate the gas handling system to reduce and control a partial pressure of oxygen in the upper and lower chambers, (b) operate the movement mechanism and the light engine to form the 3D article in a layer-by-layer manner.