3D Powder Bed Fusion Beam Scanning With Dummy Passes
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Solution Overview
Problem
In three-dimensional powder bed fusion additive manufacturing (PBF-AM), the melting of metal in one line is often affected by the heat from the next line during beam scanning, leading to potential defects in the shaped object, especially when the line length is short.
Innovation Solution
A three-dimensional PBF-AM apparatus and method that includes performing dummy scanning between the end of beam scanning on one line and the start of scanning on the next line, using a beam irradiation device to divide the build region into lines and control the electron beam to prevent melting during dummy scanning, thereby reducing heat transfer between lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If beam scanning is performed sequentially on multiple lines to melt powder material, then manufacturing efficiency is improved, but heat from the next line affects the previously melted metal causing defects
Solution Approach 1:
The patent applies preliminary action by performing dummy scanning on the next line before actual beam scanning begins. This preliminary scan creates a thermal barrier that prevents heat from the upcoming scan from affecting the previously melted metal, thereby maintaining manufacturing precision while preserving sequential scanning efficiency
Solution Approach 2:
The dummy scan acts as an intermediary thermal barrier between consecutive scanning lines. By introducing this intermediate scanning step, the patent isolates the heat zones of adjacent lines, preventing harmful thermal interaction while maintaining the overall manufacturing process efficiency
2Speed
If the time interval between beam scanning of consecutive lines is shortened, then manufacturing speed is improved, but the melt pool is disturbed by heat from the next line
Solution Approach 1:
The dummy scan is performed as a preliminary action before the actual beam scanning of the next line. This allows the system to maintain high scanning speeds while ensuring that the melt pool remains stable, as the dummy scan creates thermal isolation in advance
Solution Approach 2:
The patent introduces periodic dummy scanning actions between consecutive beam scanning operations. This periodic intervention creates regular thermal barriers that stabilize the melt pool while maintaining overall manufacturing speed through efficient cycle management
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 effectively prevents metal in one line from being affected by the heat of the next line, reducing the likelihood of defects in the manufactured object by maintaining a longer time interval between scanning lines and controlling thermal energy application.
Implementation Method 1
a beam irradiation device which irradiates the powder material spread on the build plate with a beam
Implementation Method 2
melt the powder material in the build region line by line
Implementation Method 3
performs dummy scanning to scan the beam in a state that does not cause melting of the powder material between an end of beam scanning of an M-th line and a start of beam scanning of an (M+1)th line
Data Source
AI summary
A three-dimensional PBF-AM apparatus includes: a build plate on which a powder material is spread in layers; and a beam irradiation device which irradiates the powder material spread on the build plate with a beam. The beam irradiation device divides a build region of the powder material spread on the build plate into a plurality of lines and performs beam scanning to melt the powder material in the build region line by line, and performs dummy scanning to scan the beam in a state that does not cause melting of the powder material between an end of beam scanning of an M-th (M is a natural number) line and a start of beam scanning of an (M+1)th line.