Cold-Sprayed Build Plate Structure to Resist PBF-L Warping
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Solution Overview
Problem
In laser powder bed fusion additive manufacturing, build plates face issues such as warping and tensile failure due to induced thermal stresses, and the need for material compatibility with the workpiece leads to high costs, especially with expensive materials like titanium, and large builds are prone to damage and prolonged processing times.
Innovation Solution
A build plate with a support region and a top region formed using a cold spray process to induce compressive stresses, counteracting tensile stresses, and allowing for the reuse of build plates by repairing and reapplying a metal layer with compressive stress, which is metallurgically matched to the workpiece material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If build plates are made from expensive materials like titanium to ensure material compatibility with workpieces, then reliability and compatibility are improved, but cost increases
Solution Approach 1:
The build plate is divided into two distinct regions: a support region made from cost-effective materials and a top region made from expensive materials like titanium that are metallurgically compatible with workpieces. This segmentation allows the expensive material to be used only where necessary for compatibility while reducing overall cost.
Solution Approach 2:
The top region of the build plate is specifically engineered with material properties matched to the workpiece material, while the support region uses different, less expensive materials. This local quality approach ensures compatibility where needed without unnecessarily using expensive materials throughout the entire build plate.
2Productivity
If build plates are used for larger geometry parts, then productivity is improved, but build plates warp due to tensile stresses
Solution Approach 1:
The cold spray process is used to deposit the top region material in a way that induces compressive stresses within the layer. These compressive stresses counteract the tensile stresses generated during laser powder bed fusion of large workpieces, preventing build plate warping and enabling larger geometry parts to be manufactured successfully.
3Manufacturing precision
If builds are welded onto build plates during PBF-L process, then manufacturing precision is improved, but tensile failure occurs in the build plate
Solution Approach 1:
Compressive stresses are intentionally induced in the top region through the cold spray deposition process before the PBF-L manufacturing begins. These pre-existing compressive stresses counterbalance the tensile stresses that develop when workpieces are welded onto the build plate, preventing tensile failure and spallation of the build plate.
4Productivity
If consolidate build powder is placed on build plates, then productivity is improved, but build plate spallation occurs
Solution Approach 1:
The cold spray deposited top region creates a structurally reinforced surface with compressive stresses that resist the forces generated by consolidate build powder placement. This preliminary strengthening prevents spallation and delamination of the build plate surface, enabling efficient consolidation processes without compromising build plate stability.
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 solution reduces the risk of build plate failure, enables the reuse of build plates, and lowers costs by using less expensive materials for the support region while maintaining compatibility with the workpiece, thus improving the sustainability and efficiency of the additive manufacturing process.
Implementation Method 1
The top region is formed on the support region by a cold spray process
Implementation Method 2
the top region is under a compressive stress
Data Source
Figure 1~2
Figure 3
AI summary
A build plate (12) for a powder bed fusion - laser (PBF-L) additive manufacturing system has a support region (50) and a top region (52). The top region (52) is formed on the support region (50) by a cold spray process, such that the top region (52) is under a compressive stress. The build plate (12) can be prepared by preparing the build plate support region (50) to receive the top region (52) and depositing, using a cold spray process, a layer of metal on the support region (50). The layer of metal is formed with a compressive stress to form the top region (52). The top region (52) is then machined to provide a desired surface roughness.