Polyamide 12 Powder Mixture for Laser Sintering
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Solution Overview
Problem
Existing methods for producing three-dimensional objects via laser sintering face challenges in achieving low distortion and high surface quality, particularly when using reused polyamide 12 powder, as high temperatures cause thermal and thermo-oxidative aging, leading to increased solution viscosity and compromised mechanical properties.
Innovation Solution
A powder mixture with a specific ratio of regulated polyamide 12 to unregulated polyamide 12, within the range of 10 to 30% by weight, is used to maintain molecular weight and prevent excessive aging, allowing for reduced new powder content (refresh rate) while ensuring low warpage and high elongation at break.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If reused polyamide 12 powder is used after thermal aging, then productivity is improved by reducing material waste, but manufacturing precision deteriorates due to increased distortion and reduced surface quality
Solution Approach 1:
The patent changes the chemical composition parameters of the polyamide 12 powder by controlling end group content (carboxyl groups ≤ 5 mmol/kg, amino groups ≤ 3 mmol/kg) and molecular weight (viscosity number 80-200 ml/g). These parameter adjustments prevent excessive thermal aging during reuse, maintaining manufacturing precision while enabling higher reuse rates and improved productivity
Solution Approach 2:
The patent applies preliminary stabilization treatment to the polyamide 12 powder by controlling its end group content and molecular weight before the sintering process. This preliminary action prevents degradation during thermal aging, allowing the powder to be reused multiple times without compromising manufacturing precision, thus improving productivity
2Productivity
If the proportion of new powder is reduced to increase reuse rate, then productivity is improved, but reliability deteriorates due to compromised mechanical properties
Solution Approach 1:
The patent modifies the molecular weight parameters of the polyamide 12 powder by controlling the viscosity number (80-200 ml/g) and end group content. These parameter changes ensure that even with high reuse rates (low new powder content), the mechanical properties and reliability of the sintered parts remain consistent and dependable
3Manufacturing precision
If laser sintering is performed at high temperatures, then manufacturing precision is improved by achieving proper sintering, but object-generated harmful factors increase due to thermal and thermo-oxidative aging
Solution Approach 1:
The patent converts the harmful effect of thermal aging into a beneficial outcome by formulating polyamide 12 powder with controlled end group content and molecular weight. The controlled composition ensures that thermal aging during laser sintering does not cause degradation, but rather maintains stability, allowing high temperatures to be used for precise sintering without generating harmful aging effects
Solution Approach 2:
The patent changes the chemical composition parameters of the polyamide 12 powder by controlling carboxyl end group content (≤ 5 mmol/kg), amino end group content (≤ 3 mmol/kg), and viscosity number (80-200 ml/g). These parameter changes make the powder resistant to thermal and thermo-oxidative aging, eliminating harmful effects while maintaining manufacturing precision during high-temperature laser sintering
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 enables the production of three-dimensional objects with improved mechanical properties, reduced distortion, and enhanced surface quality, allowing for a significant reduction in the new powder content required, with a refresh rate as low as 0.1% to 40%, compared to the traditional 50%.
Implementation Method 1
The energy required for the sintering or melting process is usually introduced using a laser
Implementation Method 2
a three-dimensional object is produced in layers by sintering or melting a powdery building material
Implementation Method 3
The heating device 12 is designed, for example, in the form of one or more radiant heaters (for example infrared radiators)
Implementation Method 4
a three-dimensional object is produced in layers by applying electromagnetic radiation or particle radiation to a powdery building material
Data Source
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AI summary
A powder mixture is described that is suitable for the layer-by-layer fabrication of a three-dimensional object (3) by solidifying a powdered build-up material (19). The powder mixture consists of a mixture of a first polyamide 12 powder and a second polyamide 12 powder, wherein the first polyamide 12 powder is characterized by an increase in viscosity according to ISO 307 of less than 10% when exposed under a nitrogen atmosphere for 20 hours at a temperature 10°C below its melting point, and the second polyamide 12 powder is characterized by an increase in viscosity according to ISO 307 of 15% or more when exposed under a nitrogen atmosphere for 20 hours at a temperature 10°C below its melting point.In particular, the proportion of the first polyamide 12 powder in the mixture must be between 10 and 30 percent by weight so that the manufactured objects (3) not only have good mechanical properties, but also low distortion and high surface quality.