Virtual Planarization Control for Additive Manufacturing

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Solution Overview

Problem

Additive manufacturing systems face challenges in achieving precise dimensional accuracy due to process variations such as triboelectric charge-to-mass ratios, edge lifting, and thermal effects, leading to topographical errors in printed layers.

Innovation Solution

A method involving a bitslice stack with sensors measuring surface heights and a controller assembly that compares these measurements to predicted stack heights to identify and compensate for topographical errors, allowing for virtual planarization of 3D parts and support structures without the need for physical planarizers.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If physical planarizers are used to correct surface height variations, then manufacturing precision is improved, but device complexity and hardware costs increase

Engineering Contradiction:
Improvedimensional accuracyVSAvoidphysical planarization complexities
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical physical planarization system with a computational feedback control system. Sensors measure surface heights, a controller compares measurements to predicted heights, and bitslice stack modifications compensate for deviations. This substitutes mechanical correction with optical/electronic measurement and computational adjustment, eliminating the need for physical planarizers while maintaining dimensional accuracy.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent creates a virtual model of the build surface by comparing sensor measurements to predicted stack heights. This virtual representation allows the system to identify topographical error regions and compute compensatory modifications to the bitslice stack without requiring physical intervention, thereby reducing hardware complexity while preserving manufacturing precision.

Inventive Principle:
Principle #26Copying

2Manufacturing precision

If real-time surface height measurement and compensation is implemented, then manufacturing precision is improved, but device complexity increases

Engineering Contradiction:
Improvedimensional accuracyVSAvoidcontrol system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent implements a feedback control loop where sensors continuously measure surface heights of printed layers, the controller assembly compares these measurements to predicted stack heights, and the system modifies the bitslice stack to compensate for identified deviations. This closed-loop feedback mechanism enables real-time correction of topographical errors, improving dimensional accuracy through dynamic adjustment rather than static mechanical planarization.

Inventive Principle:
Principle #23Feedback

Solution Approach 2:

The system performs self-correction by using its own measurement data to generate compensatory modifications. The controller assembly automatically adjusts the bitslice stack based on sensor feedback, eliminating the need for external manual intervention or complex mechanical correction systems. The process serves itself by identifying and correcting its own topographical errors through computational means.

Inventive Principle:
Principle #25Self-service

3Productivity

If multiple layers are developed before measuring surface heights, then productivity is improved, but measurement precision is delayed

Engineering Contradiction:
Improveprinting speedVSAvoidfeedback timing
Core Design Contradiction:
ProductivityVSMeasurement precision

Solution Approach 1:

The patent performs preliminary development of multiple layers before measurement, allowing the printing process to maintain high speed and productivity. The system develops several layers in advance, then measures their surface heights and computes compensatory modifications for subsequent layers. This preliminary action approach ensures that measurement feedback is applied proactively to future layers rather than reactively to past layers, maintaining both productivity and precision.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system cushions against potential height deviations by computing and applying compensatory modifications to the bitslice stack before the problematic layers are printed. By analyzing surface heights of previously developed layers and preemptively adjusting the bitslice stack, the system prevents topographical errors from propagating to subsequent layers, thereby maintaining measurement precision despite the time delay inherent in multi-layer development.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

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 improves dimensional accuracy and reduces material waste and hardware costs by enabling real-time adjustments during the printing process, maintaining high printing speeds while minimizing physical planarization complexities.

Implementation Method 1

latent electrostatic images are formed by electrostatic charging

Methodology Applied
Scientific EffectElectrostatic charging: Electrostatic Induction

Implementation Method 2

photoconductive material layer, where latent electrostatic images are formed by electrostatic charging, followed by image-wise exposure of the photoconductive layer by an optical source

Methodology Applied
Scientific EffectPhotoconductive material response: Photoconductivity

Implementation Method 3

measuring surface heights of the successive layers after each of the successive layers are printed

Methodology Applied
Scientific EffectSurface height measurement:

Data Source

PatentEP3119586B1Additive manufacturing with virtual planarization control
Publication Date: 2020.05.13 STRATASYS INC
  • EP3119586B1 patent drawingFigure 1
  • EP3119586B1 patent drawingFigure 2
  • EP3119586B1 patent drawingFigure 3

AI summary

A method and system (10) for printing a three-dimensional part (80), which includes printing a plurality of successive layers of the three-dimensional part (80) with the additive manufacturing system (10) based on bitslices (116) in a bitslice stack (118), measuring surface heights of the successive layers after each of the successive layers are printed, determining differences between the measured surface heights and predicted stack heights of the bitslices (116), identifying one or more topographical error regions based on the determined differences, and modifying the bitslice stack (118) to compensate for the one or more topographical error regions.