Selective Edge Binder Deposition for Additive Manufacturing
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Solution Overview
Problem
Conventional binder jetting processes require large amounts of binder for thick or large parts, leading to increased costs and potential cracking or porosity during debinding, especially in non-uniform cross sections.
Innovation Solution
A method where a binder solution is deposited on a powder layer at locations corresponding to the edge boundaries of a part, with a sintering aid solution optionally applied, reducing the amount of binder within the part while maintaining green and brown body strength by using a binder solution comprising a high percentage of monomer and thermal initiator, and a sintering aid solution in a solvent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If binder is deposited at all locations where powder is sintered, then green strength is maintained, but binder quantity increases and debinding time increases
Solution Approach 1:
The patent applies different binder deposition strategies to different regions of the part. Edge regions receive binder deposition to form a structural shell providing green strength, while interior regions may receive reduced or no binder. This localized differentiation maintains necessary green strength at critical locations while reducing overall binder quantity and debinding time.
2Strength
If binder is deposited at all locations where powder is sintered, then green strength is maintained, but debinding time increases
Solution Approach 1:
The patent implements spatially selective binder deposition where edge regions receive full binder coverage for structural integrity during green state, while interior regions receive reduced binder. This reduces the total binder volume that must be removed during debinding, thereby reducing debinding time while maintaining green strength where structurally necessary.
3Strength
If large amounts of binder are used in thick parts, then green strength is maintained, but cracking and porosity increase during debinding
Solution Approach 1:
The patent deposits binder selectively at edge regions to form a confining shell that maintains green strength and structural integrity, while reducing or eliminating binder in thick interior regions. This prevents excessive binder accumulation that would cause cracking and porosity during debinding, while the edge shell maintains necessary structural support.
Solution Approach 2:
The patent segments the binder deposition function into two roles: edge regions form a structural shell providing green strength and confinement, while interior regions use reduced binder to avoid debinding defects. This segmentation of binder functions resolves the contradiction between maintaining green strength and preventing debinding cracking.
4Loss of time
If binder is reduced in thick parts, then debinding time is shortened, but green strength decreases
Solution Approach 1:
The patent maintains green strength by concentrating binder deposition at edge regions where structural support is most critical for maintaining part geometry during handling and debinding. The edge shell provides sufficient green strength confinement while reducing binder in interior regions shortens debinding time.
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 reduces the amount of binder used, shortens debinding time, and enhances brown strength, minimizing the likelihood of cracking during debinding while maintaining part integrity.
Implementation Method 1
the binder is jetted from a print head onto successive layers of the powder in a build volume, where layers of the powder and the binder adhere to one another to form a green body part
Implementation Method 2
greater than or equal to 0.1 wt % and less than or equal to 2 wt % of a thermal initiator
Implementation Method 3
The monomer comprises at least one of a difunctional monomer and a monofunctional monomer
Implementation Method 4
The sintering aid enables an increased brown strength as compared to parts containing unbound powder
Data Source
AI summary
Various embodiments provide a method of additively manufacturing a part including depositing a layer of a powder on a working surface, depositing a binder solution on the layer of the powder at first locations, and depositing a sintering aid solution on the layer of the powder at second locations. The sintering aid solution comprises a sintering aid in a solvent. In various embodiments, the sintering aid enables an increased brown strength as compared to parts containing unbound powder. The method enables binders that provide high green strength to be used at the edges of the part, while also balancing a shortened debind time with an increased brown strength. Embodiments in which binder solution is deposited according to a predetermined pattern at second locations are also described.