Layer Scan Sequencing for Better 3D-Printed Surface Quality

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Solution Overview

Problem

Generative layer construction processes face challenges in achieving high-quality surfaces aligned parallel to layers due to temperature differences and stress in solidified materials, particularly in upskin and downskin areas, caused by varying thermal conductivity and issues with energy input and solidification.

Innovation Solution

A method and device that modify the control data for generative layer construction by prioritizing the scanning of bottom and top surface areas with energy radiation, ensuring these areas are solidified before the rest of the object cross-section, and using a gas stream to manage vapors and contaminants, thereby improving surface quality and reducing temperature inhomogeneities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If energy radiation is applied to solidify building material in generative layer construction, then the object is produced layer by layer, but temperature differences and stresses occur in the solidified material resulting in poor surface quality

Engineering Contradiction:
Improvesurface qualityVSAvoidtemperature uniformity
Core Design Contradiction:
Manufacturing precisionVSTemperature

Solution Approach 1:

The patent segments the object cross-section into multiple scan zones (first scan zone, second scan zone, third scan zone) with different scanning priorities. By dividing the scanning process into zones and assigning different temporal priorities, the patent achieves more uniform temperature distribution and reduced thermal stresses, thereby improving surface quality in upskin and downskin areas.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent applies preliminary action by scanning certain regions (particularly the first scan zone containing upskin and downskin areas) before other regions. This prioritized scanning ensures that critical surface areas are solidified first with controlled energy input, preventing temperature inhomogeneities and stress accumulation that would degrade surface quality.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If the scanning sequence is modified to prioritize bottom and top surface areas, then surface quality improves, but the production time increases

Engineering Contradiction:
Improvesurface qualityVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

The patent applies local quality by assigning different scanning priorities to different spatial zones. The first scan zone (containing upskin and downskin areas) receives high priority scanning, while the second and third zones receive lower priority. This localized differentiation improves surface quality where it matters most without unnecessarily extending the scanning of less critical regions, thus balancing production time and quality.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent performs preliminary scanning of critical surface areas (bottom and top surfaces in the first scan zone) before completing the scanning of other regions. This approach ensures that time-sensitive surface quality requirements are met first, while the remaining regions are scanned subsequently, optimizing the overall production time while maintaining high surface quality.

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

The approach enhances the quality of upskin and downskin surfaces by ensuring uniform energy input and minimizing the impact of vapors and contaminants, leading to improved homogeneity and density in the solidified material.

Implementation Method 1

solidifying the building material by supplying radiant energy to locations in a layer that are associated with the cross-section of the object in this layer

Methodology Applied
Scientific EffectThermal energy supply: Heating

Implementation Method 2

laser melting or electron beam melting

Methodology Applied
Scientific EffectLaser melting: Melting

Implementation Method 3

laser sintering (SLS or DMLS)

Methodology Applied
Scientific EffectLaser sintering: Sintering

Implementation Method 4

a gas stream is directed over the layer in a main flow direction

Methodology Applied
Scientific EffectGas flow: Convection

Data Source

PatentEP3579998B1Increase in surface quality
Publication Date: 2024.02.28 EOS GMBH ELECTRO OPTICAL SYST
  • EP3579998B1 patent drawingFigure 1
  • EP3579998B1 patent drawingFigure 2~3
  • EP3579998B1 patent drawingFigure 4

AI summary

A computer-supported method for providing control data for a generative layer construction device comprises: a first step (S1) of accessing a plurality of layer data records that have data models of a plurality of buildup material layers to be selectively solidified during production, wherein in at least one layer data record a base surface region of an object cross section exists in the associated data model, which is defined in that in at least one of p layers below the base surface region, no solidification of buildup material (15) is specified, wherein p is a predefined natural number; a second step (S2), in which the at least one layer data record is changed such that a temporal sequence for scanning the associated object cross section with energy radiation is specified such that at least one portion of the base surface region is scanned before all other parts of the object cross section to be solidified; and a third step (S3), in which the at least one layer data record changed in the second step is provided for the generation of a control data record for the generative layer construction device.