Occluding Fluids in Vat Photopolymerization Resin Management
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Solution Overview
Problem
Current 3D printing methods using SLA and DLP technologies face issues such as excessive resin usage, resin aging, part distortion due to swelling, difficulty in printing soft materials, and incompatibility with certain fluids, leading to increased costs and inefficiencies.
Innovation Solution
The use of occluding fluids, such as high-density z-fluids or low-density a-fluids, which displace resin in the vat during printing, reducing resin volume, increasing refresh rate, and decreasing resin aging, while being compatible with various additive manufacturing chemistries and allowing for the printing of soft materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If top-down printing method is used with large excess of resin, then the part can be cured by patterned light at liquid-air interface, but 80 to 90% of resin remains unreacted leading to added cost and pronounced aging
Solution Approach 1:
An immiscible support fluid is introduced as an intermediary substance between the resin and the build platform. This support fluid displaces the resin from areas not intended for printing, allowing the build platform to be raised and lowered through the resin without requiring excessive resin volume. The support fluid acts as a mediator that enables precise resin placement while maintaining the liquid-air interface curing mechanism.
Solution Approach 2:
The invention changes the physical parameters of the printing system by introducing a second fluid with different density and immiscibility properties. By selecting a support fluid with appropriate density differences from the resin, the system achieves better control over resin distribution and reduces the total resin volume needed while maintaining curing quality at the liquid-air interface.
2Manufacturing precision
If bottom-up printing method is used, then patterned light can illuminate from bottom of resin vat to cross-link photo-resin layer by layer, but excess resin remains unreacted decreasing resin refresh rate
Solution Approach 1:
The immiscible support fluid serves as a mediator that separates the resin from the build platform, enabling the build platform to move through the resin without dragging excess resin along. This allows bottom-up printing to proceed with reduced resin volume while maintaining layer-by-layer curing precision, thereby improving resin refresh rate and productivity.
3Adaptability or versatility
If high monomer content low crosslink density resin is used, then the resin can be printed, but the printed part is submerged in its own resin during printing causing swelling and distortion
Solution Approach 1:
The immiscible support fluid acts as a protective intermediary barrier between the printed part and the bulk resin. Since the support fluid is immiscible with the resin, it prevents resin from contacting and swelling the printed part, thereby maintaining dimensional accuracy while allowing the use of high monomer content resins with desired compositional flexibility.
Solution Approach 2:
The support fluid creates an inert environment around the printed part during the printing process. By being immiscible and chemically incompatible with the resin, the support fluid isolates the printed part from resin exposure, preventing swelling and distortion while allowing versatile resin composition selection.
4Adaptability or versatility
If soft material is printed, then the material can be deposited, but the initial printed state is too weak to support its own weight causing collapse
Solution Approach 1:
The denser immiscible support fluid provides a buoyant counterforce that supports the weight of soft printed materials during the printing process. This anti-weight effect prevents collapse of structures made from soft, weak materials by offsetting gravitational forces, enabling successful printing of materials that would otherwise be too weak to support themselves.
5Ease of operation
If aqueous or small molecule alcohol based fluids are used as support fluid, then the fluid can be added to resin vat, but solvent volatilization leads to densification and increased viscosity
Solution Approach 1:
The invention selects support fluids with specific physical parameters - particularly low volatility and appropriate density - to maintain stable composition throughout the printing process. By choosing fluids with these optimized parameters, the system avoids densification and viscosity changes that would occur with volatile solvents, ensuring operational ease while maintaining compositional stability.
6Ease of operation
If fluids with relatively low density compared to resin are used, then the fluid can be added to resin vat, but density differences lead to resin/z-fluid inversions
Solution Approach 1:
The invention optimizes the density parameter of the support fluid by selecting fluids with density greater than the resin. This parameter change ensures stable layering with the resin, preventing inversions while maintaining ease of operation during fluid addition and printing processes.
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 resin usage by up to 95%, decreases post-processing time, and enables the printing of soft materials by supporting them during the process, while maintaining chemical stability and compatibility with diverse resin chemistries.
Implementation Method 1
The at least one occluding fluid has a different density than the liquid polymer resin
Implementation Method 2
SLA and vat DLP use light to cause liquid resin to solidify into polymerized objects
Implementation Method 3
WO 2018/182536 discloses a method for continuous printing of a three-dimensional object wherein a support fluid is transferred from a support fluid reservoir to a resin tank
Data Source
AI summary
The present disclosure relates to the use of occluding fluids, such as a high-density fluid (a "z-fluid") or a low-density fluid (an "a-fluid"), to displace resin within a vat during 3D printing. Further, an a-fluid may act as a protective boundary for a 3D printing resin wherein the a-fluid sits on top of the printing resin. Another embodiment of the disclosure provides a process of assessing which regions of a computer-aided design (CAD) model take advantage of a buoying force supplied by the occluding fluid, such that fewer support structures are needed for printing a final CAD model compared to printing the CAD model without the occluding fluid.