3D Printing Layer Segmentation to Reduce Sink Marks
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Solution Overview
Problem
Conventional methods for producing three-dimensional objects by layer-by-layer solidification of powdered materials often result in surface defects like sink marks, especially when using conventional powders and blade geometries, which compromises the quality of the finished objects.
Innovation Solution
Applying a layer to be solidified in two or more consecutive coating steps, with each sub-layer being heated and combined to achieve the desired thickness, allowing for uniform layer formation and reduced sink marks without requiring specialized powders or coater geometries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional powder and conventional blade geometries are used, then manufacturing cost is reduced and ease of manufacture is improved, but surface quality deteriorates due to sink marks
Solution Approach 1:
The patent divides the powder layer application into multiple sequential coating steps, where each step applies a thin sub-layer that is then solidified before the next sub-layer is applied. This segmentation of the coating process into multiple thin layers prevents sink marks by avoiding the application of thick powder layers that would otherwise pool and create surface defects, while still achieving the desired total layer thickness through cumulative application.
2Manufacturing precision
If special powders with increased melt viscosity are used, then sink marks are reduced, but manufacturing cost increases and mechanical properties deteriorate
Solution Approach 1:
Instead of using special high-viscosity powders to prevent sink marks, the patent segments the powder layer into multiple thin sub-layers applied sequentially. Each sub-layer is thin enough that conventional powder does not pool or sink, eliminating the need for expensive special powders while maintaining surface quality. This approach preserves the mechanical properties of conventional powders.
Solution Approach 2:
The patent changes the parameter of layer thickness by applying multiple thin sub-layers instead of one thick layer. This parameter change (reducing individual layer thickness) prevents sink marks by reducing the weight and volume of powder that could pool during application, while using conventional powder materials that maintain good mechanical properties.
3Manufacturing precision
If special coating blade geometries are proposed, then sink marks are reduced, but device complexity increases due to retrofitting requirements
Solution Approach 1:
The patent avoids modifying the coating blade geometry by segmenting the coating process into multiple sequential steps. Instead of changing the physical shape of the blade to prevent sink marks, the system applies multiple thin sub-layers using the existing blade, solidifying each layer before applying the next. This maintains device simplicity while achieving surface quality improvement.
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 enhances surface quality by minimizing sink marks and achieving uniform layer progression, even with conventional powders, while maintaining comparable production time and equipment usage.
Implementation Method 1
a laser beam is used to solidify the powdered build-up material at the points corresponding to the respective cross-section of the object
Implementation Method 2
Such a process, known as 'selective laser sintering,'
Implementation Method 3
the powder is preheated by radiant heating between application and solidification
Data Source
Figure 1
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AI summary
A method for producing a three-dimensional object by layer-by-layer application and selective hardening of a powdery structural material by the action of energy includes the steps: application of a layer (32+33) of the powdery structural material (11) with a predetermined height (h) to a carrier (6) or a previously at least selectively hardened layer; and introduction of energy (14) from an energy source (13) to selectively harden the powdery structural material in the applied layer at the points corresponding to the cross-section of the object to be produced. The application of the layer with the predetermined height (h) is subdivided into the application of a first layer (32) with a first height (h1) that is less than the predetermined height (h) and the application of at least one second layer (33) with a second height (h2) that is less than the predetermined height (h), wherein the total height (h1+h2+...) of the applied powder sub-layers (32, 33,...) corresponds to the predetermined height (h) and the most recently applied powder layer is heated between the step of applying the first powder sub-layer and the step of applying the second powder sub-layer and any additional powder sub-layers.