Laser Sintering Duty Cycle Control for Polymer Molecular Weight

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Solution Overview

Problem

The existing laser sintering processes for rapid prototyping and manufacturing face issues with polymeric material damage due to laser power peaks, leading to molecular weight reduction and thermal damage, which affects the quality and functionality of components.

Innovation Solution

Implementing a device with a control unit that uses pulse width modulation (PWM) to set the laser to a high duty cycle of more than 60% at a clock frequency of at least 5 kHz, allowing for increased laser energy input without causing molecular weight loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser power is increased to achieve higher exposure speeds, then productivity is improved, but polymeric material is damaged due to laser power peaks causing molecular weight reduction

Engineering Contradiction:

Improveexposure speedVSAvoidmolecular weight stability

Core Design Contradiction:

ProductivityVSReliability

Solution Approach 1:

The laser power is modulated using pulse width modulation (PWM) with a duty cycle greater than 60% at a clock frequency of at least 5 kHz. This periodic modulation eliminates harmful power peaks while maintaining high average power for fast processing, resolving the contradiction between productivity and material integrity

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The invention changes the temporal distribution of laser power parameters by implementing PWM control with specific duty cycle (>60%) and frequency (≥5 kHz) settings. This transforms the power delivery from continuous peaks to controlled pulses, enabling high exposure speed without molecular weight reduction

Inventive Principle:

Principle #35Parameter changes

2Productivity

If laser power peaks are used to increase processing speed, then productivity is improved, but thermal damage occurs causing discoloration and component failure

Engineering Contradiction:

Improveprocessing speedVSAvoidthermal damage

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

By applying periodic PWM modulation with duty cycle >60% and frequency ≥5 kHz, the laser delivers energy in controlled pulses rather than continuous peaks. This eliminates thermal damage and discoloration while maintaining high processing speed through efficient energy delivery

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The invention converts the potentially harmful effect of high laser power into a beneficial process by using PWM modulation. The high average power needed for fast processing is achieved without the harmful peaks, turning what would be destructive energy into controlled, effective heating

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If laser power is reduced to avoid molecular weight loss, then material integrity is maintained, but process speed significantly slows down

Engineering Contradiction:

Improvemolecular weight stabilityVSAvoidprocess speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

PWM modulation with duty cycle >60% allows the laser to operate at high average power without harmful peaks, maintaining both molecular weight stability and high process speed. The periodic on-off pattern delivers sufficient energy for fast processing while avoiding damage

Inventive Principle:

Principle #19Periodic action

4Productivity

If high laser power is used to maintain process speed, then productivity is maintained, but released substances from polymeric materials disrupt the process by settling on lenses and pyrometers

Engineering Contradiction:

Improveprocess speedVSAvoidreleased substances

Core Design Contradiction:

ProductivityVSObject-generated harmful factors

Solution Approach 1:

The PWM modulation with duty cycle >60% and frequency ≥5 kHz creates a more controlled heating process that prevents excessive thermal degradation. This reduces the release of disruptive substances while maintaining high process speed through efficient energy delivery

Inventive Principle:

Principle #19Periodic 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 prevents molecular weight reduction and thermal damage, maintaining component quality while maintaining the process speed, as demonstrated by the solution viscosity measurements.

Implementation Method 1

a control unit which sets the laser to a duty cycle of more than 60% at a clock frequency of at least 5 kHz

Methodology Applied

Scientific EffectPulse width modulation:

Implementation Method 2

at least a laser

Methodology Applied

Scientific EffectLaser: Laser

Implementation Method 3

selective laser sintering (SLS)... the desired structures are produced layer by layer through selective melting and solidification

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 4

selective laser sintering (SLS)... selective melting and solidification

Methodology Applied

Scientific EffectSintering: Sintering

Data Source

PatentEP2548718B1Use of an apparatus and method for layerwise laser sintering of three dimensional objects

Publication Date: 2015.09.23 EVONIK OPERATIONS GMBH

Figure 1

AI summary

The present invention relates to a device for the layer-by-layer production of three-dimensional objects, a method for layer-by-layer production and corresponding shaped bodies, wherein the device comprises a control unit that sets a laser to a sensing level of more than 60%.