Additive Manufacturing Thermal Conductivity Control
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Solution Overview
Problem
Existing additive manufacturing methods, such as selective laser melting, face challenges in achieving precise dimensional accuracy and consistent layer connections due to variations in thermal conductivity and diffusivity across the powder layer, leading to potential cavities and inclusions.
Innovation Solution
An operating method that involves a first heating process to locally heat subareas of the powder layer without connecting grains, followed by a second heating process where the process beam is adjusted based on temperature profile evaluations of local thermal conductivity and diffusivity to ensure precise interconnection of grains, using a process beam generator, detection device, and control device to optimize heating parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a single heating process is used to melt and connect powder grains, then the process is simple and fast, but dimensional accuracy and layer connection quality deteriorate due to variations in thermal conductivity and diffusivity
Solution Approach 1:
The heating process is divided into two distinct stages: a first heating process that heats subareas to a temperature below melting point to pre-condition the powder, and a second heating process that melts and connects the grains. This segmentation allows each stage to be optimized independently, improving overall manufacturing precision while managing process complexity.
Solution Approach 2:
The first heating process serves as a preliminary action that pre-heats the powder grains and modifies their thermal properties before the actual melting and connection occurs in the second heating process. This preliminary conditioning of the material improves the effectiveness and precision of the subsequent melting operation.
2Manufacturing precision
If uniform heating parameters are applied across the entire powder layer, then the process is simple to control, but heating precision deteriorates due to local variations in thermal conductivity and diffusivity
Solution Approach 1:
The patent applies different heating parameters to different subareas of the powder layer based on their local thermal properties. The first heating process uses parameters optimized for pre-heating, while the second heating process uses parameters optimized for melting and connection. This local differentiation of heating quality improves precision while the systematic approach manages control complexity.
Solution Approach 2:
The patent changes heating parameters between the two processes: the first process uses lower temperature and different power settings to pre-condition the powder, while the second process uses higher temperature and adjusted power to achieve melting and connection. These parameter changes are adapted to local thermal properties, improving heating precision.
3Manufacturing precision
If the process beam directly melts and connects powder grains, then the process is efficient, but connection quality deteriorates due to unaccounted local thermal property variations
Solution Approach 1:
The first heating process performs a preliminary action on the powder grains by heating them to a temperature that modifies their thermal properties and prepares them for optimal melting and connection. This preliminary treatment ensures that when the second heating process melts the grains, the connection quality is improved due to the pre-conditioned material state.
Solution Approach 2:
The two heating processes are performed in continuous sequence without interruption to the additive manufacturing workflow. The first heating process continuously pre-conditions the powder as it is deposited, and the second heating process immediately follows to complete the melting and connection, maintaining continuous useful action throughout the manufacturing process.
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 results in improved and more precise connections of layers, enhancing the quality and accuracy of three-dimensional structures by accounting for local thermal properties, thereby reducing defects like cavities and inclusions.
Implementation Method 1
first subareas of the applied layer are heated locally by means of the process beam
Implementation Method 2
A temperature profile of the applied layer is detected by means of a detection device
Implementation Method 3
Usually sintering or melting of the applied powder takes place during the second heating process
Implementation Method 4
Usually sintering or melting of the applied powder takes place during the second heating process
Data Source
AI summary
First subareas of a layer of powder applied on a substrate are heated locally with a process beam so as to heated, but not yet interconnect the grains of the powder in the first subareas. A temperature profile of the applied layer is evaluated proximate to the first subarea as a function of the distance from the respective first subarea and/or the time. The local thermal conductivity and/or local diffusivity are determined for the respective first subarea based on the temperature profile. Second subareas of the applied layer which at least partially overlap the first subareas are then heated locally with the process beam so as to interconnect the grains of the powder in the second subareas. A process variable of the process beam influencing heating of the second subareas is determined based on the local thermal conductivity or diffusivity previously determined for the at least partially overlapping first subarea.