Porous Structure Build Compensation for Directional Scaling Errors
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Solution Overview
Problem
Rapid manufacturing technologies, such as direct metal fabrication, face directional disparities in building porous structures, leading to suboptimal porosity and structural integrity, particularly in medical implants where precise dimensions are crucial for biologic ingrowth.
Innovation Solution
The method involves modifying strut dimensions in porous structures by applying a scaling factor based on directional disparities, using local coordinate systems to decouple global and local scaling effects, and compensating for machine-specific build errors, ensuring features maintain original shape and size across different planes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If rapid manufacturing technologies are used to produce porous structures, then manufacturing efficiency is improved, but manufacturing precision deteriorates due to directional disparities in the build process
Solution Approach 1:
The patent applies preliminary action by pre-compensating for directional build disparities through scaling factors applied to the digital model before manufacturing. The system calculates and applies different scaling factors to dimensions in different build directions (X, Y, Z axes) to counteract the known systematic errors of the rapid manufacturing process, ensuring that the final manufactured dimensions match the desired specifications despite the inherent directional biases in the layer-by-layer build process
Solution Approach 2:
The patent implements parameter changes by dynamically adjusting dimensional parameters (length, width, height) of struts and features based on their orientation and position in the build volume. The system modifies model parameters using scaling factors that vary by direction and location, transforming the digital model to compensate for the non-uniform build characteristics of the rapid manufacturing process across different spatial regions
2Ease of manufacture
If uniform, non-random porous structures are used, then manufacturing ease is improved, but strength deteriorates due to weak areas at strut intersections
Solution Approach 1:
The patent applies asymmetry by transitioning from uniform, periodic porous structures to randomized non-periodic structures where strut lengths, orientations, and spacing vary statistically. This randomization eliminates the repetitive weak intersection patterns found in uniform structures, distributing stress more evenly throughout the lattice while maintaining manufacturability through algorithmic generation methods
3Device complexity
If Strut dimensions are not compensated for directional disparities, then manufacturing simplicity is improved, but reliability deteriorates due to suboptimal porosity and structural integrity
Solution Approach 1:
The patent implements local quality by applying direction-specific and location-specific scaling factors to different regions of the porous structure. Rather than applying a uniform scaling factor to the entire model, the system adjusts dimensions locally based on the build direction and position, ensuring that each region is compensated according to its specific build characteristics, thereby optimizing both porosity and structural integrity throughout the component
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 minimizes distortions and ensures accurate, consistent structure fabrication, enhancing the strength and porosity of medical implants by addressing directional disparities in the manufacturing process.
Implementation Method 1
DMF techniques produce three-dimensional structures one layer at a time from a powder which is solidified by irradiating a layer of the powder with an energy source such as a laser or an electron beam
Implementation Method 2
DMF techniques produce three-dimensional structures one layer at a time from a powder which is solidified by irradiating a layer of the powder with an energy source such as a laser or an electron beam
Implementation Method 3
The powder is fused, melted or sintered, by the application of the energy source
Implementation Method 4
The powder is fused, melted or sintered, by the application of the energy source
Implementation Method 5
The powder is fused, melted or sintered, by the application of the energy source
Data Source
Figure 1A~2
Figure 3~5B
Figure 6~7
AI summary
The present disclosure allows for more controlled modification of the input data to a Rapid Manufacturing Technologies (RMT) machinery to compensate for systematic error of the manufacturing process, such as directional build discrepancies, by performing the opposite effect to the input data. The modification is achieved with minimal unwanted distortions introduced to other portions of the structure to be built by decoupling the global scaling effects on the whole structure from the desired local effects on certain portions.