Dual-Metal 3D Printer Support Structures via Thermal Expansion Mismatch
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Solution Overview
Problem
In 3D metal object printing, the strong bonding of metal support structures with the object features complicates their removal, often requiring significant machining and risking damage to the object, and coordinating different metals for support structures is challenging due to thermal conditions affecting the build environment.
Innovation Solution
A method and apparatus for a 3D metal object printer that uses two different solid metals, one for forming the object and another for forming support structures, with a mechanism to alternate between them, allowing the support structures to be easily separated by exploiting a mismatch in thermal expansion coefficients and forming a segmented boundary for facilitated removal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the same metal is used for both the object and support structures, then strong bonding is achieved, but removal of support structures becomes difficult requiring significant machining
Solution Approach 1:
The patent applies local quality by using different metal materials for support structures versus the main object. The support structures use a first metal material while the object uses a second metal material, creating localized material differentiation. This allows support structures to bond sufficiently during printing but enable easier removal through material property differences such as thermal expansion mismatch, thereby resolving the contradiction between achieving strong bonding and facilitating support removal.
2Ease of manufacture
If a different metal is used for support structures, then easier removal is achieved, but thermal conditions affect the build environment and may weaken either the support or object
Solution Approach 1:
The patent applies parameter changes by carefully selecting metal materials with different thermal expansion coefficients and melting points. The first metal for support structures and the second metal for the object are chosen such that their thermal properties create differential expansion during cooling, enabling support removal. The parameters are optimized so that the support metal contracts more than the object metal upon cooling, creating gaps that facilitate removal while maintaining structural integrity during the printing process.
3Ease of operation
If elastomer materials are used for support structures, then easy separation is achieved, but bonding with metal object features is poor
Solution Approach 1:
The patent applies local quality by using metal material for support structures instead of elastomer, creating localized material differentiation. The metal support structures provide sufficient adhesion to metal object features during printing through metallurgical bonding, while enabling easier removal through material property differences such as thermal expansion mismatch. This resolves the contradiction by achieving both adequate bonding and facilitated removal with metal materials.
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
Enables the formation of metal support structures that do not adhere tightly to object features, allowing for easy removal without damaging the object and maintaining the printer's environment, while accommodating different thermal conditions for each metal.
Implementation Method 1
a heater configured to heat the vessel to a temperature sufficient to melt solid metal within the receptacle of the vessel
Implementation Method 2
An electrical current is passed through the coil to produce an electromagnetic field that causes the meniscus of the melted metal at a nozzle of the receptacle to separate from the melted metal within the receptacle and be propelled from the nozzle
Data Source
AI summary
A three-dimensional (3D) metal object manufacturing apparatus is equipped with two solid metal moving mechanisms that are independently operated to move two different metals into the receptacle of a vessel in a melted metal drop ejecting apparatus. The ejector is operated to form object features with melted metal drops of one of the two different metals and to form support features with melted metal drops of the other of the two different metals. The thermal expansion coefficients of the two metals are sufficiently different that the support features easily separate from the object features after the object and support features cool.