Additive Manufacturing Overhangs via Extrinsic Support

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Solution Overview

Problem

Existing additive manufacturing methods face difficulties in producing parts with unsupported sections, as the deposited material collapses under its own weight or lacks a supporting layer for deposition, making it impossible to create features like ribs or bores with free surfaces.

Innovation Solution

The method involves depositing a first stratification with an extrinsic support and attachment surface, allowing the deposition of material on the support and attachment surface, and then removing the support after solidification, enabling the production of parts with unsupported sections by using an extrinsic support that cooperates with the part's positioning during manufacturing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If additive manufacturing is used to deposit material in successive layers, then manufacturing complexity is reduced and material utilization is improved, but unsupported parts cannot be produced as material collapses under its own weight

Engineering Contradiction:
Improveadditive manufacturing capabilityVSAvoidunsupported part production
Core Design Contradiction:
Ease of manufactureVSManufacturing precision

Solution Approach 1:

A sacrificial support structure is introduced as an intermediary element during the additive manufacturing process. This support structure provides temporary mechanical support to unsupported parts during material deposition, preventing material collapse. After the part is fully manufactured, the sacrificial support is removed, leaving the desired unsupported features intact.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The sacrificial support structure is constructed in advance before the actual part manufacturing begins. This preliminary action ensures that the support is in place to receive and stabilize the deposited material from the first layer, enabling the creation of overhangs and unsupported features that would otherwise be impossible to manufacture additively.

Inventive Principle:
Principle #10Preliminary action

2Manufacturing precision

If conventional machining techniques are used to produce parts with undercut zones, then manufacturing precision is maintained, but production time and cost increase significantly

Engineering Contradiction:
Improvepart dimensional accuracyVSAvoidproduction time
Core Design Contradiction:
Manufacturing precisionVSProductivity

Solution Approach 1:

Instead of removing material through conventional machining to create undercut zones and unsupported features, the invention inverts the approach by adding material through additive manufacturing. The sacrificial support enables the direct additive creation of features that would traditionally require complex subtractive machining, thereby dramatically reducing production time while maintaining precision.

Inventive Principle:
Principle #13The other way round (Inversion)

3Loss of substance

If full additive manufacturing is used to produce complex parts, then material utilization is optimized, but unsupported sections remain impossible to manufacture

Engineering Contradiction:
Improvematerial utilization efficiencyVSAvoidpart geometry capability
Core Design Contradiction:
Loss of substanceVSAdaptability or versatility

Solution Approach 1:

The sacrificial support acts as a temporary intermediary that enables full additive manufacturing of complex geometries. By providing the necessary mechanical support during deposition, it allows the manufacturing of parts with overhangs, ribs, and undercut zones that would otherwise require hybrid manufacturing approaches, thus optimizing material utilization while expanding geometric capability.

Inventive Principle:
Principle #24Intermediary (Mediator)

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 allows for the successful production of stepped parts with variable sections, including undercut zones, by providing mechanical support during additive manufacturing, improving precision and surface finish through subsequent machining, and enabling the creation of parts that would otherwise be impossible with conventional additive methods.

Implementation Method 1

fixing said extrinsic support extending between said first lamination and the free surface of the unsupported part not yet produced

Methodology Applied
Scientific EffectMechanical support: Mechanical Force

Implementation Method 2

depositing a lamination, called free lamination, on said support and on the attachment surface of the first lamination; disassemble the support after the loose lamination solidifies

Methodology Applied
Scientific EffectSolidification: Freezing

Data Source

PatentEP3445515B1Process for additive manufacturing a multilevel article with variable section comprising an overhang
Publication Date: 2020.05.27 ECOLE CENTE DE NANTES
  • EP3445515B1 patent drawingFigure 1~3
  • EP3445515B1 patent drawingFigure 4~5

AI summary

The invention concerns a method for the additive manufacturing, by material deposition, of a stepped part having a variable cross-section comprising an unsupported portion, said method comprising the steps consisting of: a. depositing a first layer of material (201, 203) comprising a positioning shape (211, 213) for positioning an extrinsic support (210, 215) and an engagement surface (212, 214); b. attaching a removable extrinsic support (210, 215) extending between said first layer and the free surface of the unsupported portion that has not yet been produced, to the positioning shape (211, 213), allowing the engagement surface (212, 214) to emerge from said first layer; c. depositing a layer, referred to as a free layer (202, 204), on said support (210, 215) and on the engagement surface (212, 214) of the first layer; d. dismounting the support (210, 215) after the free layer (202, 204) has solidified.