Stereolithography Shrinkage Control via Variable Laser Power

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Solution Overview

Problem

Stereolithography techniques face challenges in minimizing differential shrinkage, leading to distortions and deformations in 3D objects, particularly in large flat surfaces, due to uneven material contraction, which existing methods attempt to address through complex redesigns of scanning and software but result in slower production times and reduced quality.

Innovation Solution

The method involves adjusting the stimulation power and pre-stimulation waiting time for each layer based on parameters from preceding and following layers, using fuzzy logic to determine optimal conditions, which minimizes shrinkage without requiring complex software redesigns and maintains part quality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If complex redesign of scanning techniques and software patterns is used to reduce shrinkage, then manufacturing precision is improved, but device complexity increases and productivity decreases

Engineering Contradiction:
Improvedimensional accuracyVSAvoidsoftware complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent changes the parameter of stimulation power from a constant value to a variable that depends on the position within the layer and the layer number. By defining stimulation power as a function of spatial coordinates and layer index, the method achieves differential curing control without complex software redesign, directly resolving the contradiction between precision improvement and device complexity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent introduces a pre-stimulation waiting time parameter that is set in advance based on layer characteristics before the actual stimulation occurs. This preliminary timing adjustment allows the resin to be in the optimal state for curing, reducing shrinkage effects while maintaining simple scanning patterns and avoiding complex real-time control software

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If complex redesign of scanning techniques and software patterns is used to reduce shrinkage, then manufacturing precision is improved, but productivity decreases

Engineering Contradiction:
Improvedimensional accuracyVSAvoidconstruction time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent modifies the stimulation power parameter dynamically based on position and layer number, enabling uniform shrinkage control across different regions. This approach maintains fast scanning speeds because it does not require complex pattern redesign or multiple scanning passes, thus improving precision without sacrificing productivity

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

By pre-calculating and setting the waiting time before stimulation based on layer parameters, the method prepares the resin in advance for optimal curing. This eliminates the need for multiple subsequent exposure steps or time-consuming pattern adjustments, achieving high precision while maintaining fast construction times

Inventive Principle:
Principle #10Preliminary action

3Productivity

If standard stimulation power is used for all layers, then productivity is maintained, but manufacturing precision deteriorates due to differential shrinkage

Engineering Contradiction:
Improveconstruction speedVSAvoiddimensional accuracy
Core Design Contradiction:
ProductivityVSManufacturing precision

Solution Approach 1:

The patent implements position-dependent and layer-dependent stimulation power variation. The stimulation power is adjusted as a function of spatial coordinates within the layer and the layer number, creating a controlled gradient that compensates for differential shrinkage. This maintains productivity because the scanning pattern itself remains simple and fast, while precision is improved through the intelligent parameter modulation

Inventive Principle:
Principle #35Parameter changes

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 effectively reduces differential shrinkage, enhances the accuracy and strength of 3D objects, and maintains high quality without visible markings or increased production time, improving reproducibility and functionality.

Implementation Method 1

the sections of the building area that are part of the object to be constructed are illuminated, thereby causing the resin on the illuminated areas to polymerize and harden

Methodology Applied
Scientific EffectPhotopolymerization: Photopolymerisation

Data Source

PatentEP2433778B1Method for reducing differential shrinkage in stereolithography
Publication Date: 2020.11.04 MATERIALISE NV
  • EP2433778B1 patent drawingFigure 1a~1b
  • EP2433778B1 patent drawingFigure 2a~2b
  • EP2433778B1 patent drawingFigure 2c

AI summary

The present invention relates to a new and improved stereolithography method and system for generating a three-dimensional object by forming successive, adjacent, cross-sectional laminae of that object, thereby providing an object being specially processed to reduce differential shrinkage.