Extrusion Rate Control for Meniscus Stabilization in 3D Printing

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Solution Overview

Problem

Extrusion-based additive manufacturing systems face challenges in maintaining consistent meniscus height during the deposition of materials, leading to variations in extrusion rates and inferior model quality due to factors like meniscus dry down, latent heating, and filament diameter variations, which result in poor seam quality and increased porosity.

Innovation Solution

A method is introduced where the extrusion rate is reduced to a slower, constant rate at a predetermined point before the end of a tool path, allowing the meniscus height to normalize within the liquefier assembly, eliminating the need for purge operations and ensuring consistent deposition.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the extrusion rate is maintained at a constant high rate throughout the tool path, then productivity is improved, but the meniscus height becomes unstable leading to poor manufacturing precision

Engineering Contradiction:

Improveextrusion rateVSAvoidmeniscus height consistency

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The extrusion rate is applied periodically with two distinct phases: a higher extrusion rate for most of the tool path to maintain productivity, and a reduced extrusion rate near the end point to allow meniscus normalization. This periodic variation in extrusion rate resolves the contradiction by achieving both high productivity and meniscus stability at different stages of the deposition process.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The extrusion rate is reduced in advance before reaching the end point of the tool path, allowing the meniscus to normalize prior to completing the deposition. This preliminary action prevents meniscus instability at critical locations while maintaining high extrusion rates for the majority of the path, thus resolving the contradiction between productivity and precision.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If purge operations are performed to normalize meniscus height, then manufacturing precision is improved, but loss of time increases

Engineering Contradiction:

Improveseam qualityVSAvoidbuild time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The method eliminates discrete purge operations by continuously adjusting the extrusion rate throughout the tool path. The extrusion rate is reduced near the end point to maintain meniscus stability without interrupting the deposition process, thereby achieving both high manufacturing precision and continuous productive action without time loss.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The extrusion rate parameter is dynamically changed based on the position along the tool path. By reducing the extrusion rate near the end point rather than performing separate purge operations, the system achieves meniscus normalization while maintaining continuous deposition, thus improving seam quality without increasing build time.

Inventive Principle:

Principle #35Parameter changes

3Manufacturing precision

If the extrusion rate is reduced to normalize meniscus height, then manufacturing precision is improved, but productivity decreases

Engineering Contradiction:

Improvedeposition consistencyVSAvoidbuild speed

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The extrusion rate is adjusted locally based on the specific requirements of different portions of the tool path. The higher extrusion rate is applied to the majority of the path where productivity is critical, while the reduced rate is applied only near the end point where meniscus stability is paramount. This local differentiation resolves the contradiction by optimizing both precision and productivity in their respective zones.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of reducing the extrusion rate for the entire tool path, the method applies partial action by reducing the rate only for a specific portion near the end point. This partial reduction is sufficient to achieve meniscus normalization and improve deposition consistency at critical locations while maintaining high productivity for the majority of the build process.

Inventive Principle:

Principle #16Partial or excessive 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 reduces variations in extrusion rates, improves seam quality, and allows for continuous deposition processes, enhancing the overall quality and efficiency of 3D model building by maintaining a stable meniscus height, thus minimizing material waste and build time.

Implementation Method 1

melting the consumable material filament in the liquefier to form a melt of molten material

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 2

extruding the melt out of the liquefier assembly

Methodology Applied

Scientific EffectExtrusion: Extrusion

Data Source

PatentUS8815141B2Method for building three-dimensional models with extrusion-based additive manufacturing systems

Publication Date: 2014.08.26 STRATASYS INC

AI summary

A method for building a three-dimensional model with an extrusion-based additive manufacturing system having an extrusion head, the method comprising depositing a consumable material from a liquefier assembly at an extrusion rate to substantially normalize a meniscus height within the liquefier assembly.