Additive Manufacturing Beam Path Strategy for Sub-Surface Porosity Elimination
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional additive manufacturing methods using galvanometer type scanners result in discontinuity in scanning paths, leading to small but significant areas of unmelted powder that act as stress risers in the finished part, requiring additional processing steps like hot isostatic processing to consolidate powder and improve surface finish.
Innovation Solution
The proposed method involves a beam path that includes a surface contour vector, a plurality of parallel hatch vectors, and an offset contour vector, which together ensure that all powder regions are processed in a single pass, eliminating the need for subsequent consolidation steps while maintaining a suitable surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a galvanometer type scanner is used to melt powder layers in a linear X-Y orientation with rastering, then the scanning process can be completed, but discontinuity in scanning paths occurs resulting in unmelted powder areas that act as stress risers
Solution Approach 1:
The patent applies preliminary action by implementing a multi-pass scanning strategy where the energy beam first performs a contour scan along the part boundaries, then executes hatch scans through the interior, and finally performs a second contour scan. This preliminary structured approach ensures complete melting coverage without leaving unmelted powder areas, resolving the contradiction between scanning speed and melting completeness.
Solution Approach 2:
The patent implements continuity of useful action by designing continuous contour scanning paths that smoothly traverse the part boundaries without abrupt stops or starts. The contour vectors are generated to maintain continuous energy beam action along the contours, eliminating the discontinuities and unmelted areas that occur with traditional rastering methods while maintaining high scanning speed.
2Device complexity
If traditional rastering is used to break up the linear scanning path into smaller sections, then the scanning can be managed, but small areas of unmelted powder remain therebetween acting as stress risers
Solution Approach 1:
The patent applies segmentation by dividing the scanning process into distinct functional passes: contour scans that follow part boundaries and hatch scans that cover the interior. This segmentation allows each scanning type to be optimized independently - contour scans ensure complete boundary melting while hatch scans fill the interior - eliminating the unmelted areas between raster sections that compromise part strength.
3Manufacturing precision
If additional processing steps like hot isostatic processing are used to consolidate powder, then surface finish and powder consolidation are improved, but time, equipment, and expense increase
Solution Approach 1:
The patent implements preliminary action by incorporating all necessary melting and consolidation operations directly into the additive manufacturing build process itself. The multi-pass scanning strategy (contour-hatch-contour) ensures complete powder melting and consolidation during the primary manufacturing step, eliminating the need for subsequent hot isostatic processing or other consolidation steps, thereby reducing total processing time and equipment requirements while maintaining high surface finish quality.
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 eliminates the need for additional processing steps like hot isostatic processing, reducing time, equipment, and expense, while preventing high-cycle fatigue defects by ensuring complete melting of powder regions in a single build process.
Implementation Method 1
selectively melting the powder using a laser
Implementation Method 2
selectively melting the powder using an electron beam
Implementation Method 3
operating an energy beam to facilitate additive manufacturing... ensuring complete melting of powder regions
Implementation Method 4
operating an energy beam to facilitate additive manufacturing... ensuring complete melting of powder regions
Data Source
Figure 1
Figure 2
Figure 3A~3C
AI summary
A method for operating an additive manufacturing apparatus, the method comprises directing a first energy beam along a surface contour vector in a build plane. A second energy beam is directed along a plurality of substantially parallel hatch vectors disposed in the build plane inward of the surface contour vector. A sum of the surface contour vector and the plurality of hatch vectors define a processed powder region in the build plane. A third energy beam is directed along an offset contour vector in the build plane. The offset contour vector includes a plurality of unprocessed powder regions in the build plane between the surface contour vector and the plurality of hatch vectors.