Liquid Interface Leveling in Additive Fabrication

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Solution Overview

Problem

Conventional additive fabrication devices face challenges in maintaining a consistent and even liquid-liquid interface due to movement and turbulence, leading to inconsistent layer formation and increased time required for equilibrium, especially with viscous photopolymers and thinner layers.

Innovation Solution

Incorporating a leveling element that moves through the supporting liquid to smooth the interface and a film between the liquid photopolymer and supporting liquid to limit intermixing and maintain a flat surface, along with selecting immiscible liquids based on density and reactivity to reduce adhesive forces.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a supporting liquid is used in additive fabrication, then layer formation is enabled, but the liquid-liquid interface becomes unstable and turbulent, leading to inconsistent layer formation

Engineering Contradiction:
Improvelayer formationVSAvoidliquid-liquid interface stability
Core Design Contradiction:
Ease of manufactureVSStability of the object's composition

Solution Approach 1:

A film is introduced as an intermediary barrier between the liquid photopolymer and supporting liquid, preventing direct contact and turbulence at the liquid-liquid interface while still allowing the supporting liquid to provide structural support for layer formation

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin film is placed between the liquid photopolymer and supporting liquid to stabilize the interface, prevent mixing, and eliminate turbulence while maintaining the functional benefits of both liquids

Inventive Principle:
Principle #30Flexible shells and thin films

2Reliability

If the liquid photopolymer and supporting liquid are allowed to mix, then equilibrium is reached, but the process time increases significantly

Engineering Contradiction:
Improveequilibrium stateVSAvoidequilibrium time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The film acts as a selective barrier that prevents mixing between the liquid photopolymer and supporting liquid, allowing the system to maintain a stable equilibrium state without requiring extensive mixing time

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The film is pre-installed between the liquids to prevent mixing from occurring in the first place, eliminating the need for time-consuming equilibrium processes

Inventive Principle:
Principle #10Preliminary action

3Ease of manufacture

If thicker layers are used, then manufacturing is easier, but the precision and consistency of layer formation decreases

Engineering Contradiction:
Improvelayer formation easeVSAvoidlayer consistency
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

The thin film provides a stable, flat interface that enables precise control over thin layer formation, allowing for high manufacturing precision while maintaining ease of operation through the film's structural support

Inventive Principle:
Principle #30Flexible shells and thin films

4Object-affected harmful factors

If incompatible liquids are used, then adhesive forces are reduced, but the liquids may react or mix adversely

Engineering Contradiction:
Improveadhesive forcesVSAvoidliquid reaction or mixing
Core Design Contradiction:
Object-affected harmful factorsVSObject-generated harmful factors

Solution Approach 1:

The film serves as a protective intermediary that allows incompatible liquids to be used together by preventing direct contact and adverse reactions while maintaining the benefit of reduced adhesive forces

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The thin film creates a physical barrier that prevents mixing and adverse reactions between incompatible liquids while still allowing the system to benefit from using liquids with reduced adhesive properties

Inventive Principle:
Principle #30Flexible shells and thin films

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 solution enables faster and more consistent layer formation by minimizing bulges and distortion, allowing for the use of incompatible liquids and reducing the time needed for the liquids to reach equilibrium, thereby improving the efficiency and accuracy of the additive fabrication process.

Implementation Method 1

a leveling element arranged adjacent to the supporting liquid and at least one controller configured to move the leveling element through the supporting liquid along an upper surface of the supporting liquid

Methodology Applied
Scientific EffectFluid flow:

Implementation Method 2

a film coupled to the container and arranged over and in contact with the supporting liquid

Methodology Applied
Scientific EffectPhysical barrier:

Implementation Method 3

an apparatus for additive fabrication configured to form a plurality of layers of material on a build platform by directing actinic radiation onto a liquid photopolymer

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Implementation Method 4

the build platform configured to be movable through the liquid photopolymer

Methodology Applied
Scientific EffectMechanical motion:

Data Source

PatentEP4028243B1Liquid interface techniques for additive fabrication and related systems
Publication Date: 2024.02.14 FORMLABS INC
  • EP4028243B1 patent drawingFigure 1A
  • EP4028243B1 patent drawingFigure 1B
  • EP4028243B1 patent drawingFigure 1C

AI summary

According to some aspects, an additive fabrication apparatus is provided configured to form layers of material on a build platform (203), each layer of material being formed so as to contact a supporting liquid (205) or a film (507) disposed within a container (201), in addition to the build platform, a liquid photopolymer (206), and/or a previously formed layer (220) of a material. The additive fabrication apparatus may comprise a container (201) and a leveling element (207), wherein the leveling element (207) is configured to move across a liquid-liquid interface (204) to promote or create a flat interface between the two liquids. According to some aspects, the additive fabrication comprises a film (507) disposed between two liquids, wherein the film (507) maintains or provides a flat surface at the interface of the two liquids.