Selective Laser Sintering Heat Energy Adjustment for Polymer Parts
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Solution Overview
Problem
Existing selective laser sintering (LS) methods for polymer powders, such as PEKK, face challenges in maintaining mechanical strength and geometric accuracy due to variations in thermal conductivity between powdered and solid forms, leading to overheating and unwanted fusion issues, particularly in constructing voids and parts with tight tolerances.
Innovation Solution
The method adjusts the heat energy introduced by electromagnetic radiation based on build data specifications for previous and subsequent layers, using a pre-factor to calculate the adjusted heat energy per unit area, accounting for the heat affected zone and reducing oversintering and unwanted fusion, thereby improving geometric accuracy and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If standard laser sintering methods are used with polymer powder, then the object can be formed, but thermal conductivity variations cause overheating and reduced mechanical strength
Solution Approach 1:
The patent applies dynamics by making the laser power adjustable and variable during the sintering process. The system dynamically adapts the laser power based on the local geometry and material state, transitioning from static to dynamic control to prevent overheating while maintaining mechanical strength in the constructed object.
Solution Approach 2:
The patent changes the laser power parameter during the sintering process based on the local situation. By adjusting the power parameter dynamically according to the thermal conductivity variations between powder and solid regions, the system prevents localized overheating while ensuring proper sintering, thereby improving mechanical strength.
2Reliability
If laser power is increased to ensure complete sintering, then material fusion is improved, but geometric accuracy and tolerance are reduced due to oversintering
Solution Approach 1:
The patent applies local quality by treating different regions of the build area with different laser power settings. Instead of using a uniform power level, the system adjusts the power locally based on the specific geometric features and material state at each position, ensuring complete sintering where needed while preventing oversintering in other areas, thus maintaining geometric accuracy.
3Ease of manufacture
If uniform laser power is applied across all layers, then the process is simple, but mechanical strength varies due to thermal conductivity changes between powder and solid regions
Solution Approach 1:
The patent transitions from a static, uniform laser power approach to a dynamic, adaptive power control system. The system continuously adjusts the laser power based on real-time conditions and pre-calculated parameters, making the manufacturing process more complex but ensuring consistent mechanical strength throughout the object by accounting for thermal conductivity variations.
4Productivity
If high laser power is used to reduce build time, then productivity increases, but unwanted fusion occurs between layers leading to defects
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the laser power parameter during the building process. Instead of using consistently high power to maintain productivity, the system varies the power level according to the specific layer and position, ensuring complete sintering when needed while preventing unwanted fusion between layers, thus maintaining both productivity and precision.
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 enhances the mechanical strength and geometric accuracy of polymer parts by accurately controlling heat input, reducing overheating and unwanted fusion, and maintaining the specified geometry of the CAD model, especially in constructing voids and complex geometries.
Implementation Method 1
electromagnetic radiation, for example from a CO 2 laser, is used to bind a powder building material at select points
Implementation Method 2
Selective laser sintering (LS) is a layer-wise additive manufacturing technique
Implementation Method 3
Preheating is typically accomplished by one or more radiant heaters
Implementation Method 4
bind a powder building material at select points to create a solid structure
Data Source
Figure 1
Figure 2A~2B
Figure 3A~3B
AI summary
A method of producing an object 100 from a polymer powder using a laser sintering system 10, whereby the laser sintering system 10 introduces heat energy to solidify select points of a layer L0 of polymer powder according to build data of the object 100 and adjusts the heat energy according to solidification of select points of other layers.