Effect of Printing Parameters on Material Properties and Testing Results

Photopolymer 3D printing is a process-dependent manufacturing technology. The properties of printed parts are not intrinsic constants of the liquid resin, but responses of a printed and post-processed system obtained under specific reference conditions.

This page explains how printing parameters, printer technologies and testing methodologies influence reported material properties and why values must be interpreted as typical performance rather than universal constants.

Why material properties are not intrinsic constants

Unlike bulk thermoplastics or metals, photopolymer materials undergo in-situ polymerization during printing. The final network structure is created layer by layer and depends on how energy is delivered, how layers interact and how the printed part is post-processed.

As a result, the same formulation may exhibit different mechanical, thermal, surface or functional behavior when printed under different conditions.

Properties depend on the full material–printer–process system

Final part behavior emerges from the interaction of multiple variables, including:

• resin formulation and selected version

• printer technology (SLA, DLP, LCD, MLCD, laser or projection based)

• exposure power, time and curing strategy

• layer thickness and build orientation

• washing efficiency and post-curing conditions

• ageing and environmental exposure

Changing any of these variables may significantly alter the measured properties of printed parts.

Typical values versus intrinsic constants

Reported properties such as Young’s modulus, tensile strength, elongation, impact resistance, Shore hardness, glass transition temperature (Tg) or heat deflection temperature (HDT) represent typical performance obtained under defined reference configurations.

They are not intrinsic material constants and should not be interpreted as universally reproducible values across different printers, workflows or testing setups.

Effect of printer technology and exposure strategy

Different printer architectures deliver different energy distributions and curing dynamics:

• laser-based SLA systems rely on scanned point exposure

• DLP and LCD systems use projected area exposure

• MLCD systems typically deliver higher and more uniform power

These differences influence curing depth, crosslink density, anisotropy and surface chemistry, leading to variations in mechanical performance, dimensional accuracy and surface finish.

Effect of printing specifications

Key printing specifications that strongly influence properties include:

• layer thickness

• exposure energy per layer

• number and duration of burn-in layers

• build orientation and support strategy

These parameters affect interlayer bonding, shrinkage, anisotropy, surface quality and dimensional accuracy.

Effect of post-processing and testing methodology

Post-processing steps such as washing time, solvent choice, drying and post-curing energy have a major impact on final properties.

Testing methodology also plays a critical role. Specimen geometry, build orientation, conditioning, test speed and environmental conditions may lead to large variations even when testing the same formulation.

For this reason, testing standards must always be interpreted together with the printing and post-processing conditions used to generate the test specimens.

Biocompatibility and safety considerations

For biocompatible applications, printing and post-processing parameters influence extractables, surface chemistry and biological response.

Maximum biocompatibility requires:

• qualified formulations

• controlled printing workflows

• validated washing and post-curing protocols

Deviations from qualified workflows may compromise safety margins and biological performance.

Reference configurations and reproducibility

To communicate material behavior in a meaningful and transparent way, 3Dresyns defines reference configurations and qualified workflows.

These configurations provide a reproducible basis for comparison, documentation and technical communication, while acknowledging the inherent variability of photopolymer systems.

Relationship to Instructions for Use and fine tuning

Instructions for Use (IFU) define qualified workflows for printing, cleaning and post-curing.

Fine tuning additives and parameter adjustments allow controlled shifts in performance, such as printing speed, resolution or dimensional accuracy, but introduce trade-offs that must be understood and validated.

Governing principle

In photopolymer additive manufacturing, material properties are process-dependent responses. Reported values describe typical performance obtained under reference configurations and qualified workflows. Final properties must always be validated by users under their own printing, post-processing and testing conditions.