Additive Manufacturing Microstructure Control via Layer Duration

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Solution Overview

Problem

Additive manufacturing processes, such as direct metal laser melting, result in inhomogeneous microstructures and material properties due to high energy beam and un-melted material interactions, leading to challenges in achieving homogeneous microstructures within objects, despite attempts to control temperature profiles and beam characteristics.

Innovation Solution

A method is introduced to control microstructure in metal powder additive manufacturing by maintaining a constant sum of irradiation device melting time, idle time, and recoating time for selected layers, while keeping other operation parameters constant, using a duration controller to ensure consistent microstructure across the object.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If high power laser beam is used to melt metal powder layers quickly, then productivity is improved, but microstructure homogeneity deteriorates due to high cooling rates and fast solidification

Engineering Contradiction:

Improvemanufacturing speedVSAvoidmicrostructure homogeneity

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent applies dynamics by making the laser processing parameters dynamic rather than static. The laser power, scan speed, and hatching distance are adjusted layer-by-layer based on the evolving thermal state of the build platform. This allows the system to maintain optimal melting conditions while controlling cooling rates, thereby achieving both high productivity and microstructure homogeneity without requiring post-manufacturing heat treatment

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements parameter changes by systematically varying laser processing parameters (power, scan speed, hatching distance) across different layers. The control method monitors thermal accumulation and adjusts parameters to maintain consistent thermal cycles, transforming the fixed parameter approach into a adaptive parameter strategy that resolves the contradiction between fast processing and microstructure control

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If same operation parameters are used across entire object, then device complexity is reduced, but microstructure homogeneity deteriorates in different regions

Engineering Contradiction:

Improvecontrol algorithm complexityVSAvoidmicrostructure uniformity

Core Design Contradiction:

Device complexityVSManufacturing precision

Solution Approach 1:

The patent applies segmentation by dividing the build process into discrete layers and further segmenting the object into regions with different thermal characteristics. Each layer is processed with parameters optimized for its specific position and thermal state. This segmentation strategy enables region-specific control without requiring complex real-time monitoring, achieving microstructure uniformity through systematic parameter variation across layers

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by pre-calculating and planning the laser processing parameters for each layer before actual manufacturing. The control method determines optimal parameters for upcoming layers based on predicted thermal accumulation, allowing the system to proactively compensate for thermal effects rather than reacting to them, thereby simplifying real-time control while maintaining microstructure homogeneity

Inventive Principle:

Principle #10Preliminary 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

This approach simplifies the control of microstructures and material properties by maintaining consistent irradiation device operation parameters, reducing residual stresses and achieving homogeneous microstructures within the object, which conventional methods often struggle to achieve.

Implementation Method 1

an irradiation beam source system for manufacturing the selected object by successive solidification of metal powder material layers using irradiation

Methodology Applied

Scientific EffectIrradiation: Laser

Implementation Method 2

successive solidification of metal powder material layers using irradiation on positions corresponding to a cross-sectional area

Methodology Applied

Scientific EffectSolidification: Freezing

Data Source

PatentUS10695867B2Controlling microstructure of selected range of layers of object during additive manufacture

Publication Date: 2020.06.30 GE INFRASTRUCTURE TECH LLC

AI summary

Controlling microstructure in an object created by metal powder additive manufacturing is disclosed. During additive manufacturing of one or more objects using an irradiation beam source system, for each respective layer in a selected range of layers including a cross-sectional area of the one or more objects including the selected object, a duration controller controls actuation of each irradiation device to maintain constant a sum of: an irradiation device melting time, an irradiation device idle time, and a recoating time expended applying a new powder material layer, while otherwise maintaining all other operation parameters of each irradiation device constant.