3D Printing Surface Roughness Control via Variable Agent Density

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Solution Overview

Problem

Additive manufacturing systems face challenges in achieving consistent surface properties, particularly surface smoothness and roughness, due to variations in build material and solidification mechanisms, making it difficult to produce objects with desired surface characteristics efficiently and cost-effectively.

Innovation Solution

The system employs an agent distributor to deliver coalescing agent at different contone densities for interior and surface portions of a three-dimensional object, allowing for controlled solidification patterns to achieve a target surface roughness, using a combination of coalescing agents and modifiers to manage energy application and material coalescence.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If a uniform agent delivery pattern is used throughout the object, then the manufacturing process is simple, but the surface roughness cannot be precisely controlled

Engineering Contradiction:
Improvesurface roughness controlVSAvoidagent delivery pattern complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent applies different agent delivery patterns to different regions of the object: a first pattern with higher contone density for interior portions and a second pattern with lower contone density for surface portions. This local differentiation enables precise surface roughness control while maintaining structural integrity in the interior, directly resolving the contradiction between manufacturing precision and device complexity.

Inventive Principle:
Principle #3Local quality

2Manufacturing precision

If multiple different build materials are used to achieve desired surface properties, then surface quality improves, but manufacturing cost and complexity increase

Engineering Contradiction:
Improvesurface qualityVSAvoidmanufacturing cost and complexity
Core Design Contradiction:
Manufacturing precisionVSEase of manufacture

Solution Approach 1:

Instead of using multiple different build materials, the patent varies the contone density parameter of the same coalescing agent delivery pattern. By adjusting the contone density (number of agent droplets per unit area) between interior and surface portions, the patent achieves different surface properties using a single material system, thereby improving surface quality while reducing manufacturing complexity and cost.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If high contone density is used throughout the object, then complete solidification is achieved, but surface roughness control is lost

Engineering Contradiction:
Improvesolidification completenessVSAvoidsurface roughness
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent applies high contone density agent delivery to interior portions to ensure complete solidification and structural reliability, while applying low contone density agent delivery to surface portions to achieve precise surface roughness control. This spatially differentiated approach resolves the contradiction by allowing each region to have the contone density appropriate for its functional requirements.

Inventive Principle:
Principle #3Local quality

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 enables the efficient and cost-effective production of three-dimensional objects with precise surface roughness, improving surface quality by varying the density and pattern of agent delivery, thereby overcoming the limitations of existing additive manufacturing techniques.

Implementation Method 1

a coalescing agent, which is a material that, when a suitable amount of energy is applied to a combination of build material and coalescing agent, may cause the build material to coalesce and solidify

Methodology Applied
Scientific EffectCoalescence:

Implementation Method 2

the coalescing agent may act as an absorber of applied energy such that the portions of build material having coalescing agent experience coalescence and solidification

Methodology Applied
Scientific EffectEnergy absorption: Absorption (EM radiation)

Implementation Method 3

a coalescence modifier agent may also be selectively delivered to layers of build material. A coalescence modifier agent may serve to modify the degree of coalescence of a portion of build material on which the coalescence modifier agent has been delivered or has penetrated

Methodology Applied
Scientific EffectCoalescence modification:

Data Source

PatentEP3271150B1Generating three-dimensional objects with target surface roughness
Publication Date: 2021.08.25 HEWLETT PACKARD DEVELOPMENT COMPANY LP
  • EP3271150B1 patent drawingFigure 1~3
  • EP3271150B1 patent drawingFigure 4~5
  • EP3271150B1 patent drawingFigure 6a~6d

AI summary

An agent distributor may be to selectively deliver agent at a first contone density and at a second contone density different from the first contone density respectively onto an interior portion and a surface portion of successive layers of build material in respective first and second patterns in accordance with data representing a threedimensional object to be generated, so that the build material is to solidify to form slices of the three-dimensional object in accordance with the first and second patterns, and so that the three-dimensional object is to achieve a target surface roughness as a result of the second contone density of the second pattern.