3D Printing Scanning Strategy for Surface Roughness Control
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Solution Overview
Problem
Existing powder bed fusion techniques face challenges in achieving high-quality three-dimensional workpieces, particularly in terms of surface roughness, due to limitations in the scanning strategies and irradiation parameters.
Innovation Solution
The apparatus and method involve a control unit that generates control data to guide the radiation beam to move away from the central axis for more than 50% of the contour length, using multiple scanning units if necessary, to optimize the scanning direction and adapt irradiation power and speed based on the angle between the radiation beam and the central axis, ensuring improved surface quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the radiation beam scans along the contour of the work piece, then the work piece is produced, but the surface roughness deteriorates when the beam moves towards the central axis
Solution Approach 1:
The patent inverts the conventional scanning approach by directing the radiation beam to move away from the central axis rather than towards it during contour scanning. This reversal of the scanning direction prevents the formation of re-entrant corners and ensures that the beam always approaches the contour from the work piece interior, thereby improving surface roughness and eliminating the need for complex post-processing operations.
2Area of stationary object
If multiple scanning units are used to irradiate large work pieces, then the build chamber size increases, but the system complexity increases
Solution Approach 1:
The patent divides the build chamber into multiple irradiation areas, each assigned to a dedicated scanning unit. This segmentation allows each scanning unit to operate independently within its assigned area, simplifying the control strategy and reducing the complexity of coordinating multiple scanning units while still enabling the production of large work pieces.
3Productivity
If the radiation beam scans at high speed, then productivity increases, but the energy density decreases affecting solidification quality
Solution Approach 1:
The patent implements dynamic adjustment of scanning parameters by adapting the scanning speed and irradiation power based on the local geometry and thickness of the work piece. This allows the system to maintain optimal energy density for solidification quality while achieving high productivity through increased scanning speeds in appropriate regions.
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 significantly reduces surface roughness and enhances the overall quality of the three-dimensional workpieces by maintaining consistent energy density and adjusting parameters to suit varying thicknesses and angles, leading to improved manufacturing outcomes.
Implementation Method 1
The radiation penetrating into the powder layer causes heating and consequently melting or sintering of the raw material powder particles
Implementation Method 2
The radiation penetrating into the powder layer causes heating and consequently melting or sintering of the raw material powder particles
Implementation Method 3
The radiation penetrating into the powder layer causes heating and consequently melting or sintering of the raw material powder particles
Data Source
AI summary
An apparatus for producing a three-dimensional work piece is provided. The apparatus comprises an irradiation unit comprising at least one scanning unit configured to scan a radiation beam over an uppermost layer of raw material powder to predetermined sites of the uppermost layer of the raw material powder in order to solidify the raw material powder at the predetermined sites. An axis corresponding to the radiation beam when it impinges on the uppermost layer of raw material powder at an angle of 90° is defined as a central axis for the scanning unit. The apparatus further comprises a control unit configured to receive work piece data indicative of at least one layer of the three-dimensional work piece to be produced, and assign at least a part of a contour of the layer of the three-dimensional work piece to the at least one scanning unit. According to a first aspect, the control unit is configured to generate control data for controlling the irradiation unit, the control data defining a scan strategy of the radiation beam such that for more than 50% of a predefined length, the radiation beam moves away from the central axis, the predefined length being defined as a length the radiation beam moves along the contour assigned to the at least one scanning unit, excluding sections concentric with regard to the central axis. Further, corresponding methods and computer program products are provided.