Polyamide Powder Viscosity Control for Reusable Powder Bed Fusion
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Solution Overview
Problem
Polyamide powders used in powder bed fusion methods suffer from aging phenomena due to thermal and thermooxidative damage, leading to inhomogeneous mechanical properties and the inability to be reused, necessitating mixing with virgin powder, which increases costs and environmental impact.
Innovation Solution
A polyamide powder with controlled solution viscosity increase under simulated construction conditions, ensuring homogenous mechanical properties and reusability by maintaining a specific solution viscosity within a defined range, preferably 1.55 to 1.75, and incorporating additives for improved processibility and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If polyamide powder is reused after construction operations, then cost reduction and environmental protection are achieved, but the powder undergoes thermal and thermooxidative damage causing aging and inhomogeneous mechanical properties
Solution Approach 1:
The patent applies parameter changes by precisely controlling the solution viscosity of polyamide powder within the range of 1.55 to 1.75 and limiting viscosity increase to 10-40% after 24 hours at 10°C below melting temperature. This parameter control ensures that recycled powder maintains homogeneous mechanical properties while enabling repeated reuse in construction operations.
2Manufacturing precision
If polyamide powder is exposed to high temperatures during construction operations, then sintering and shaping are achieved, but thermal and thermooxidative damage occurs causing chain extension and molecular weight increase
Solution Approach 1:
The patent applies preliminary action by pre-selecting and controlling the solution viscosity of the polyamide powder before construction operations begin. By ensuring the initial viscosity is within 1.55 to 1.75 and predicting the viscosity increase will remain within 10-40% after aging, the powder is pre-conditioned to resist excessive chain extension and molecular weight changes during subsequent thermal exposure in construction operations.
3Ease of manufacture
If a mixture of two polyamides with different viscosity characteristics is used, then powder bed fusion can be performed, but extreme inhomogeneities develop over time resulting in anisotropic mechanical properties
Solution Approach 1:
The patent applies homogeneity by specifying that the polyamide powder should consist of a single polyamide type with controlled solution viscosity (1.55 to 1.75) and limited viscosity increase (10-40% after 24 hours aging). This eliminates the inhomogeneity problem inherent in mixtures of different polyamides, ensuring uniform mechanical properties and eliminating anisotropy in the constructed parts.
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
The solution provides polyamide powders with uniform mechanical properties and allows for repeated reuse, reducing costs and environmental impact while maintaining consistent performance in shaped bodies.
Implementation Method 1
during a construction operation the unused powder is exposed over lengthy periods to high temperatures scarcely below its melting temperature, thus resulting in the problem that these environmental conditions can cause the powder to undergo an aging process where it suffers thermal and/or thermooxidative damage
Implementation Method 2
these environmental conditions can cause the powder to undergo an aging process where it suffers thermal and/or thermooxidative damage
Implementation Method 3
the amine and carboxylic acid end groups react with one another and cause extension of the polyamide chains
Data Source
AI summary
A polyamide powder for powder bed fusion methods is described. The polymer exhibits a solution viscosity to ISO 307 of 1.55 to 1.75 and an increase in solution viscosity of 10% to 40%, preferably 20% to 30%, when under a nitrogen atmosphere it is subjected to a temperature 10° C. below its melting temperature for 24 h.