The 3Dresyns® Curing Rate Control System
Engineering-level exposure calibration for multifunctional photopolymer materials.
The 3Dresyns® Structured Selection Framework connects material selection, exposure calibration, dimensional verification and empirical screening within a controlled photopolymer engineering workflow.
The 3Dresyns® Curing Rate Control System (CRT) provides a structured engineering framework for selecting initial exposure conditions from measured curing behaviour rather than relying only on fixed printer presets or static exposure tables.
3Dresyns® photopolymer materials are multivariable systems. Printing behaviour depends on the complete material-printer-process-post-processing chain, including formulation, actual irradiance, wavelength, target layer thickness, temperature and post-curing workflow.
CRT therefore provides calibration logic, not a universal exposure setting.
Why Fixed Printing Settings Are Not Enough
Printer-specific exposure presets can be useful starting references, but actual vat-photopolymerization systems may differ in optical power, irradiance distribution, wavelength behaviour and LED condition.
Consequently, the same nominal exposure time should not automatically be expected to generate identical cured depth, dimensional behaviour, adhesion or process stability across different SLA, DLP or LCD systems.
CRT addresses this variability by relating exposure conditions to measured cured thickness under defined optical conditions.
Fixed settings can lose relevance when printer irradiance, optical distribution, layer thickness or other relevant process variables change.
The CRT methodology therefore uses measured curing behaviour as an engineering reference for subsequent printer-specific calibration.
What CRT Is Designed to Do
Structured exposure development
CRT is designed to support:
- measurement of curing response under defined exposure conditions;
- comparison between exposure time and cured thickness;
- selection of starting exposure windows;
- recalibration when target layer thickness changes;
- assessment of different speed-resolution trade-offs;
- interpretation of curing behaviour at different irradiance conditions; and
- subsequent dimensional verification using calibration geometries.
CRT does not eliminate the need to print and verify the actual material-printer-process configuration.
Changing Layer Thickness
A major advantage of CRT-based calibration is that the exposure condition can be reassessed when the target Z layer thickness changes.
- Need faster printing? Increase layer thickness and recalibrate exposure.
- Need finer Z resolution? Reduce layer thickness and recalibrate exposure.
- Need a different speed-resolution balance? Use the CRT dataset to select a new starting exposure region and verify it on the actual printer.
The same resin can therefore be used with different calibrated exposure conditions, provided the resulting process is appropriately checked for the intended workflow.
A Data-Driven Calibration Framework
CRT datasets describe the relationship between exposure time and measured cured thickness under controlled optical conditions.
Data may be generated at 405 nm or 385 nm to represent common vat-photopolymerization wavelength conditions.
The dataset can support exposure selection according to variables including:
- measured printer irradiance in mW/cm²;
- selected layer thickness;
- target cured thickness;
- dimensional-control requirements;
- required green strength; and
- adhesion behaviour.
This provides a more structured basis for calibration than transferring one exposure time unchanged between different printer systems.
How the CRT Workflow Works
- Measure or obtain the relevant printer irradiance in mW/cm² where possible.
- Identify the wavelength condition relevant to the printer and dataset.
- Select the intended layer thickness.
- Consult or generate the corresponding curing-depth dataset.
- Identify an initial exposure region consistent with the target cured thickness and process objective.
- Print the relevant calibration geometry.
- Verify dimensional and process behaviour.
- Adjust the exposure where required.
This workflow reduces dependence on uncontrolled trial-and-error but does not remove the need for printer-specific verification.
Fast CRT Logic for Routine Calibration
For routine implementation, an initial fast CRT may be started using three exposure checkpoints:
- 5 s
- 10 s
- 15 s
Measure cured thickness at each checkpoint and evaluate both cured thickness and qualitative green strength.
Where additional resolution is needed, add 1–2 additional points within the interval relevant to the target layer thickness and actual printer irradiance.
These checkpoints are intended as a rapid characterization approach. They are not universal printing settings.
CRT Measurement Protocol
CRT datasets may use different exposure sequences depending on curing kinetics.
Fast-Curing Resins
Typical exposure sequence:
1, 2, 3, 5, 8, 75 seconds
Slow-Curing Resins
Typical exposure sequence:
2, 5, 8, 11, 15, 75 seconds
The 75-second high-dose point serves as a reference point within the CRT sequence and may also support interpretation of initial adhesion-layer behaviour.
Important: CRT exposure sequences are illustrative checkpoints. Different systems may require shorter or longer intervals according to actual irradiance, curing kinetics, pigmentation, additives, temperature, viscosity and target layer thickness.
Choosing a Starting Exposure from CRT
As an initial engineering rule within the CRT methodology, standard-layer exposure can be selected by comparing cured thickness with the intended layer thickness and applying an appropriate cure-thickness margin.
Typical Starting Ranges
- Fast, brittle or highly reactive resins: approximately 1.0–1.2× the target layer thickness.
- Slower, softer, less brittle or more peel-sensitive resins: approximately 1.3–1.5× the target layer thickness.
These factors are approximate starting ranges, not universal acceptance criteria.
Different materials may require different exposure margins even at the same nominal layer thickness because curing, mechanical, physical and adhesion behaviour can differ.
- Under-cured behaviour: soft, weak, tender or insufficient green strength may indicate that exposure should be increased.
- Over-cured behaviour: excessive brittleness, adhesion, loss of detail or excessive Z growth may indicate that exposure should be reduced.
These observations should be interpreted together with dimensional calibration and actual printing behaviour rather than used as isolated pass/fail criteria.
Exposure Time, Irradiance and Dose
Exposure time alone does not completely describe the optical condition.
Within the CRT framework, exposure dose is related to irradiance and exposure time:
This relationship is useful when comparing exposure conditions, but equivalent nominal dose should not automatically be interpreted as guaranteed equivalent printing performance between different machines.
Printer optics, wavelength behaviour, irradiance distribution and other material-process variables remain relevant and the transferred condition should be verified on the receiving printer.
Transfer Between Printers
CRT supports transfer assessment, not automatic transferability
CRT can support transfer from one printer condition to another by using measured curing behaviour, irradiance and wavelength information rather than copying exposure time alone.
However, changing printer may also change:
- optical architecture;
- actual irradiance;
- irradiance distribution;
- wavelength condition;
- build-platform behaviour;
- vat mechanics; and
- other process variables.
For this reason, a CRT-derived condition transferred to a different printer should be treated as a structured starting point and verified through the applicable calibration workflow.
Engineering Interpretation
CRT datasets may also be interpreted using the Jacobs working curve model.
- Critical exposure (Ec): minimum exposure associated with initiation of polymerization within the model.
- Penetration depth (Dp): effective optical penetration parameter describing the curing-depth response.
These parameters provide a quantitative way to describe and compare curing behaviour under the conditions used to generate the dataset.
Jacobs Working Curve Model
Where:
- Cd = cured depth;
- E = exposure dose;
- Ec = critical exposure; and
- Dp = penetration depth.
Exposure dose is calculated as:
Ec and Dp should be interpreted in the context of the wavelength, material and optical conditions used to obtain the underlying data.
CRT and Dimensional Control
CRT helps establish exposure conditions, but it does not by itself guarantee dimensional accuracy.
After selecting an exposure region, dimensional behaviour should be checked using the applicable calibration geometries and Structured Calibration workflow.
Changes in exposure may affect cured depth, feature definition, adhesion and dimensional behaviour, so CRT and dimensional calibration should be treated as connected but distinct engineering steps.
CRT and Final Material Properties
CRT characterizes curing response and supports exposure calibration. It does not by itself establish the final mechanical, thermal, dimensional or application performance of the printed part.
Final properties may depend on the complete material-printer-process-post-processing chain, including exposure history, geometry, cleaning and post-curing.
Where final mechanical or functional performance is important, use the relevant screening, characterization and application-validation workflow after exposure calibration.
Included Documentation and Calibration Tools
3Dresyns photopolymer materials are supplied with:
- Instructions for Use (IFU)
- Calibration STL files for dimensional verification:
Optional Curing Rate Tables provide additional curing-depth data to support exposure-parameter development.
CRT Service Options
CRT Basic
- curing rate table: exposure time vs cured thickness;
- recommended starting exposure conditions; and
- measurements generated under defined 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); and
- engineering interpretation of curing behaviour.
Recommended for formulation development, material comparison and research projects.
Price: 200 €
Example CRT Curve
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.
Professional and Engineering Use
The 3Dresyns® Curing Rate Control System is intended for engineering, research, dental, medical and industrial users requiring structured exposure calibration and improved understanding of photopolymer curing behaviour.
Reference to dental, medical or other regulated environments does not by itself constitute regulatory validation or approval of the customer's final Product or printing process.
Important Limitations
What CRT Does Not Establish by Itself
CRT should not be interpreted by itself as:
- a universal exposure table for every printer;
- a guarantee that identical exposure time produces identical cure depth on different machines;
- a guarantee that equivalent nominal dose produces identical printed results;
- a guarantee of dimensional accuracy;
- a guarantee of mechanical properties;
- final application validation;
- printer certification or OEM validation; or
- regulatory qualification of the final Product.
Relevant settings should be verified under the actual material, printer, layer thickness and process conditions used for production.
Related Documentation
Use the links below to move from exposure calibration to dimensional verification, diagnosis, material screening and application-specific validation.
The 3Dresyns® Curing Rate Control System (CRT) is an exposure-calibration methodology based on measured photopolymer curing behaviour. CRT provides structured starting conditions and quantitative curing information, but exposure settings remain dependent on the actual material, wavelength, irradiance, printer, layer thickness and processing workflow. CRT-derived conditions must therefore be verified on the equipment and process in which they will be used.