The 3Dresyns® Curing Rate Control System

Engineering-level exposure control for multifunctional photopolymer materials.

The 3Dresyns® Curing Rate Control System (CRT) provides a structured engineering framework for selecting exposure conditions based on measured curing behaviour, rather than relying only on fixed presets or static exposure tables.

3Dresyns® photopolymer materials are multivariable systems. Final printing performance depends on the full material–printer–process–post-processing chain, including resin formulation, real irradiance, wavelength, target layer thickness, temperature and post-curing workflow.

Why fixed printing settings are not enough

Many resin suppliers provide static exposure parameters for specific printer models or isolated layer-thickness presets. In practice, real vat photopolymerization systems vary in optical power, irradiance distribution, wavelength behaviour and LED ageing.

As a result, fixed exposure times do not necessarily provide consistent curing depth, dimensional accuracy, adhesion behaviour or process stability across different SLA, DLP and LCD platforms.

The CRT approach addresses this problem by linking exposure time to measured cured thickness under defined optical conditions.

Why CRT is more flexible than fixed parameter presets

A major advantage of CRT-based calibration is that it allows the user to re-optimise exposure settings for different Z layer thicknesses depending on whether the priority is higher printing speed, higher Z resolution, improved dimensional control or a different balance between these variables.

With CRT, the user can move from one target layer thickness to another and re-select the corresponding exposure window in a structured way.

• Need faster printing? Increase layer thickness and recalibrate exposure.
• Need finer Z resolution? Reduce layer thickness and recalibrate exposure.
• Need different trade-offs for different parts? Use the same resin with different validated CRT-derived settings.

This is one of the main advantages of CRT compared with workflows based only on fixed parameter presets tied to isolated Z-layer configurations.

A data-driven calibration framework

CRT datasets describe the relationship between exposure time and cured thickness measured under controlled optical conditions.

Data is generated at 405 or 385 nm to match the optical conditions of typical vat photopolymerization systems.

This allows users to determine appropriate exposure parameters according to:

• measured printer irradiance (mW/cm²),
• selected layer thickness (Z resolution),
• target curing depth and dimensional control requirements,
• required green strength and adhesion behaviour.

This approach enables more consistent calibration across printers with different optical architectures and light intensities.

How the system works

The CRT workflow follows a simple engineering logic:

• measure or obtain the light power output of the printer (mW/cm²),
• select the intended layer thickness,
• consult or generate the curing-depth dataset,
• determine exposure parameters aligned with process objectives,
• validate the selected settings with reference calibration geometries.

This structured method reduces reliance on trial-and-error calibration and supports more reproducible printing workflows.

Fast CRT logic for routine calibration

For routine implementation, a fast CRT can often be started with only three points: 5 s, 10 s and 15 s.

• Measure cured thickness at 5 s, 10 s and 15 s.
• Evaluate both cured thickness and qualitative green strength.
• Add 1–2 extra points only in the interval relevant to the target Z layer thickness and the real irradiance of the printer.

This is often sufficient for rapid workflow implementation because initial adhesion layers can frequently be screened separately using long-exposure reference conditions, while the main unknown becomes the correct standard-layer exposure.

CRT measurement protocol

CRT datasets are generated using exposure sequences designed to capture curing behaviour across different resin kinetics.

Fast-curing resins

• Typical exposure sequence (seconds): 1, 2, 3, 5, 8, 75

Slow-curing resins

• Typical exposure sequence (seconds): 2, 5, 8, 11, 15, 75

The final long exposure point (75 seconds) acts as a high-dose reference point to improve interpretation of curing behaviour and to support initial adhesion-layer evaluation.

Important note: exposure times in CRT tables are illustrative checkpoints, not universal settings. Different systems may require shorter or longer intervals depending on real irradiance, resin kinetics, pigmentation, additives, printing temperature, viscosity and target layer thickness.

How to choose a starting exposure from CRT

As a general rule, select a standard exposure that cures approximately the target layer thickness multiplied by an appropriate cure-thickness factor.

• Fast, brittle or highly reactive resins: typically start near 1.0–1.2× the target layer thickness
• Slower, softer, less brittle or more peel-sensitive resins: typically start near 1.3–1.5× the target layer thickness

Important note: these factors are approximate. Different resins may show different kinetic, mechanical, physical and adhesive behaviour and may therefore require different exposure margins even at the same nominal layer thickness.

• Under-cured (soft, weak, tender, insufficient green strength) → increase exposure
• Over-cured (too brittle, excessive adhesion, loss of detail, excessive Z growth) → reduce exposure

Engineering interpretation

CRT datasets can also be interpreted using the Jacobs working curve model, which describes photopolymer curing behaviour.

• Critical exposure (Ec) – minimum energy required to initiate polymerization
• Penetration depth (Dp) – effective optical penetration depth of curing light

These parameters provide a quantitative description of photopolymer curing behaviour and allow engineering-level comparison between materials and processing conditions.

Jacobs working curve model

Cd = Dp · ln(E / Ec)

Where Cd is cured depth, E is exposure dose, Ec is critical exposure and Dp is penetration depth.

Exposure dose is defined as:

Dose (mJ/cm²) = irradiance (mW/cm²) × exposure time (s)

Included documentation and calibration tools

All 3Dresyns photopolymer materials are supplied with:

• Instructions for Use (IFU)
• Calibration STL files for dimensional validation
  • Download 3Dtest1
  • Download 3Dtest2

Optional Curing Rate Tables provide additional curing-depth data to support exposure parameter selection.

CRT service options

CRT Basic

• curing rate table (exposure time vs cured thickness),
• recommended starting exposure settings,
• measured under controlled optical conditions.

Price: 50 €

CRT Engineering Upgrade – Photopolymer Characterization

• full CRT dataset,
• Jacobs working curve modelling,
• extraction of penetration depth (Dp),
• extraction of critical exposure (Ec),
• engineering interpretation of curing behaviour.

Recommended for formulation development, material comparison and research projects.

Price: 200 €

Example CRT curve

Designed for professional users

The 3Dresyns® Curing Rate Control System is intended for engineering, research, dental, medical and industrial users seeking improved process reproducibility, dimensional control and structured exposure calibration.

Rather than relying only on fixed presets, the CRT approach supports adaptable calibration aligned with multifunctional photopolymer material design.

CRT availability and online purchase

Curing Rate Tables (CRT) are available as an optional add-on when purchasing 3Dresyns photopolymer materials.

All materials include IFU documentation and calibration STL files as standard.

Related documentation

• Structured calibration & dimensional control
• Effect of printing parameters on material properties
• Technical documentation