Integral Support Architecture for Thermal Stress in Metal 3D Printing
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Solution Overview
Problem
High temperature solid freeform fabrication techniques, such as powder bed processing, face challenges with thermally induced stresses and thermal shrinkage contraction, leading to dimensional inaccuracies and stability issues, as well as potential damage during the manufacturing process due to the robustness required for levelling blades.
Innovation Solution
An integral support architecture is developed that provides regions of varying stiffness and elasticity around the component, allowing for tension and flexibility during manufacturing, which can be altered post-manufacture by breaking struts to accommodate thermal expansion and contraction, thereby preventing warping or cracking. This support is built using an outer frame connected by struts, including omega springs and linear struts, and can be designed to remain in place during post-processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a robust levelling blade is used to level the powder bed, then the manufacturing process can proceed, but the manufactured article may be damaged due to the robustness required
Solution Approach 1:
A support structure is built around the article during manufacturing to preemptively protect it from damage by the levelling blade. The support acts as a preliminary protective measure that prevents the blade from contacting and potentially damaging the delicate article features.
Solution Approach 2:
The support structure serves as an intermediary element between the levelling blade and the article. It absorbs the mechanical interaction, allowing the blade to level the powder without directly contacting the article, thus preventing damage while maintaining the manufacturing process.
2Adaptability or versatility
If high temperature SFF is used to form metallic components, then complex structures can be manufactured, but thermally induced stresses and thermal shrinkage contraction cause dimensional inaccuracies
Solution Approach 1:
The support structure is designed with varying stiffness characteristics that change during the manufacturing process. The support provides different levels of constraint at different stages, allowing the article to undergo controlled thermal expansion and contraction while maintaining dimensional accuracy. The support stiffness is adjusted to accommodate thermal effects.
Solution Approach 2:
The support structure applies preliminary counteracting forces to compensate for expected thermal shrinkage and distortion. By pre-positioning the support with specific stiffness characteristics, the system anticipates and counteracts the thermally induced stresses before they cause dimensional inaccuracies.
3Stability of the object's composition
If support pillars are used to prevent bowing during manufacture, then the component is supported against gravity, but the supports require removal following manufacture adding post-processing steps
Solution Approach 1:
The support structure is designed as a temporary, disposable element that serves its purpose during manufacturing and then is easily removed or left in place depending on requirements. The support is built with material and structural characteristics that allow for easy removal or integration, minimizing post-processing complexity.
Solution Approach 2:
The support structure is integrated with the article during manufacturing, and in some embodiments, the support is left in place and becomes part of the final component. This merging eliminates the need for separate removal steps and can provide ongoing functional benefits.
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 support architecture effectively reduces stress and damage during manufacturing, simplifies post-processing, and allows for more precise control over thermal expansion and contraction, enhancing the dimensional accuracy and stability of metallic components.
Implementation Method 1
A laser 16 is directed towards the component and forms a melt pool 18 in the upper surface thereof
Implementation Method 2
The powder is melted by the heat from the laser
Implementation Method 3
As the laser moves from the deposition location the melted powder cools to form a deposit
Implementation Method 4
the arrangement of the support is altered, by breaking at least a portion thereof, following manufacture of the metallic article by solid freeform fabrication and before the post-manufacture processing
Implementation Method 5
thermally induced stresses and the associated thermal shrinkage contraction
Data Source
Figure 1~2
Figure 3~4
AI summary
A method of forming a component from solid freeform fabrication comprising the step of building an integral support around the component during manufacture thereof. The stiffness the support provides to the component is selected to minimise deformation of the component either during the manufacture of the component or during a subsequent heat treatment process.