Polymer Powder Bed Fusion Densification for Low-Porosity Parts

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Solution Overview

Problem

Additive manufacturing (AM) parts produced using current methods exhibit reduced strength and ductility due to porosity, which affects their toughness.

Innovation Solution

A sintering method involving prolonged exposure to incident light at controlled intensity and temperature to densify powder material, followed by controlled cooling to form a sintered article, reducing porosity and enhancing mechanical properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If conventional laser sintering is used to build parts rapidly, then productivity is improved, but porosity increases which reduces strength and ductility

Engineering Contradiction:

Improvebuild speedVSAvoidmechanical strength

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent applies periodic action by implementing multiple heating cycles with alternating high and low intensity. The process uses a first heating cycle at high intensity to rapidly densify the powder bed, followed by a second heating cycle at lower intensity to eliminate residual porosity. This periodic heating pattern allows the system to maintain high productivity while achieving the densification needed for improved mechanical strength and ductility.

Inventive Principle:

Principle #19Periodic action

2Strength

If prolonged heating is applied to densify powder material and reduce porosity, then strength is improved, but build speed decreases

Engineering Contradiction:

Improvemechanical strengthVSAvoidbuild speed

Core Design Contradiction:

StrengthVSProductivity

Solution Approach 1:

The patent implements periodic action through alternating heating cycles of different intensities. The first high-intensity cycle rapidly densifies the material, while the second lower-intensity cycle completes the densification process. This periodic approach achieves thorough densification for improved strength without requiring continuously prolonged heating, thereby maintaining acceptable build speeds.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent applies parameter changes by varying the heating intensity between two distinct cycles. The first cycle uses high intensity parameters for rapid initial densification, then transitions to a second cycle with lower intensity parameters to eliminate remaining porosity. This dynamic adjustment of heating parameters enables complete densification while optimizing the overall processing time to maintain productivity.

Inventive Principle:

Principle #35Parameter changes

3Productivity

If high optical intensity is used for rapid sintering, then productivity is improved, but porosity remains which reduces ductility

Engineering Contradiction:

Improvebuild speedVSAvoidductility

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The patent uses periodic action with two distinct heating cycles. The first cycle applies high optical intensity to maintain rapid build speed, while the second cycle uses reduced intensity to thoroughly eliminate porosity. This periodic variation in heating intensity ensures complete densification for improved ductility and reliability without sacrificing the productivity gains from rapid initial sintering.

Inventive Principle:

Principle #19Periodic action

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 method results in sintered articles with less than 2% porosity and improved mechanical properties, maintaining build speed while achieving enhanced ductility and toughness.

Implementation Method 1

projecting incident light from a source onto a surface area of the layer of powder material, wherein the incident light is projected at a predetermined optical intensity for a sufficient time to densify the layer of powder material

Methodology Applied

Scientific EffectLight heating: Heating

Implementation Method 2

cooling the layer of densified material to a sufficient temperature to solidify or vitrify the layer of densified material to form a layer of sintered material

Methodology Applied

Scientific EffectCooling and solidification: Freezing

Implementation Method 3

cooling the layer of densified material to a sufficient temperature to solidify or vitrify the layer of densified material

Methodology Applied

Scientific EffectVitrification: Vitrification

Data Source

PatentUS12485606B1System and method for improving mechanical properties of polymer powder bed fusion processes

Publication Date: 2025.12.02 UNIV OF SOUTH FLORIDA

AI summary

Sintering methods comprising (a) providing a layer of powder material on a platform; (b) projecting incident light from a source onto a surface area of the layer of powder material, wherein the incident light is projected for a sufficient time to densify the layer of powder material and form a layer of densified material; (c) optionally cooling the layer of densified material to a sufficient temperature to solidify or vitrify the layer of densified material to form a layer of sintered material; and (d) repeating steps (a) to (c) to form a sintered article in a layer-wise fashion are disclosed. The incident light may cause complete melting of the powder material or heat the powder material above its glass transition temperature. In general, the incident light is projected simultaneously and for a time span substantially the same as formation of the layer of densified material.