Adaptive 3D Infill Toolpaths for Overfill and Underfill Control
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Solution Overview
Problem
Current 3D printing technologies, particularly FDM, face challenges in generating toolpaths that accurately fill complex geometries without over- or underfilling, leading to mechanical defects and inefficiencies due to limitations in nozzle size and extrusion width variation.
Innovation Solution
A method involving the computation of a medial axis skeleton to determine adaptive bead widths and distributions, ensuring continuous and smooth toolpaths that minimize over- and underfill areas by varying the extrusion width based on local feature radii and bead counts, effectively addressing the limitations of existing toolpath generation strategies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If uniform inward offsets with nozzle size are used to generate contour-parallel toolpaths, then the outline shape accuracy is improved, but overfill and underfill areas are created causing pressure build-up and part defects
Solution Approach 1:
The patent applies local quality by varying the extrusion bead width along the toolpath based on the local geometry of the polygon. Instead of using a uniform bead width, the system calculates the distance from each point on the toolpath to the polygon boundary and adjusts the bead width locally to ensure complete filling without overfill or underfill, thereby maintaining both outline accuracy and print reliability
Solution Approach 2:
The patent implements dynamics by making the extrusion bead width a dynamic parameter that changes continuously along the toolpath. The bead width is adjusted in real-time based on the local feature size and distance to boundaries, transforming the static uniform width approach into a dynamic adaptive width system that responds to geometric variations
2Manufacturing precision
If adaptive width toolpaths are used to avoid over- and underfills, then the manufacturing precision is improved, but the device complexity increases due to limited nozzle width range
Solution Approach 1:
The patent applies parameter changes by modifying the extrusion bead width parameter along the toolpath based on geometric calculations. The system computes the required bead width at each position using the distance to polygon boundaries and local feature radii, then adjusts the extrusion parameters to achieve the desired variable width without requiring complex hardware modifications
Solution Approach 2:
The patent replaces complex mechanical width adjustment mechanisms with a computational approach. Instead of physically changing nozzle geometry or using complex mechanical systems to vary bead width, the system uses software-based toolpath generation that calculates and directs the extrusion process to achieve variable width beads through controlled deposition patterns
3Manufacturing precision
If the extrusion width is varied to match local feature sizes, then the manufacturing precision is improved, but the homogeneity of material properties deteriorates
Solution Approach 1:
The patent applies local quality by tailoring the extrusion bead width to match local feature requirements. The system calculates the optimal bead width at each position based on the distance to boundaries and local geometry, ensuring precise filling of narrow features while maintaining appropriate width in broader areas, thereby achieving both precision and material homogeneity through localized adaptation
4Manufacturing precision
If contour-parallel extrusion is used to achieve accurate outlines, then the manufacturing precision is improved, but the productivity decreases due to limited layer coverage
Solution Approach 1:
The patent applies segmentation by dividing the layer filling process into multiple passes with different functions. The first pass uses contour-parallel extrusion to accurately define the outline and primary structure, while subsequent passes fill the remaining interior areas. This segmentation allows each pass to be optimized for its specific purpose, maintaining outline accuracy while improving overall layer coverage efficiency
Data Source
AI summary
The invention relates to a method of determining toolpaths for an infill structure for a digital 3D model. The invention provides for a framework for planning toolpaths with control over the adaptive width for minimizing over- and underfill and introduce a beading scheme which reduces the bead width variation compared to the state of the art. We show that this framework supports various control schemes (so-called ‘beading schemes’) for determining the bead spacing and extrusion widths. Furthermore we present an approach to accurately realize adaptive bead width. The proposed method provides for a geometric framework allowing various adaptive bead width control schemes used to generate contour-parallel toolpaths which minimize under- and overfill.