Power difference of DLP, LCD & MLCD printers and its consequences
Each printer model (even different units of the same printer model) have different light power across the printing area (the vat/resin tank) available for curing the resins, with differences of around 300% or higher.
This document published by the FDA: Technical Considerations for Additive Manufactured Medical Devices in page 14 clearly highlights that:
Optimal settings and parameters for a single model of a machine can vary greatly when printing different devices or components. Furthermore, optimal settings and parameters can vary between machines of the same model even when printing the same devices or components.
See below the evidence and proof of facts: the power of two commercial MLCD printers, the Phrozen Sonic Mini with 0.6 mW/cm2 vs the Anycubic Mono X with 1.7 mW/cm2 measured with a commercial light meter UV-420 of 400 Euro with a wavelength measuring range 375-475 nm and a maximum peak wavelength at 420 nm.
Similarly, DLP printers can have light power across the vat from 0.5 mW/cm2 up to 30 mW/cm2 or higher for most commercial DLP printers.
This huge difference in light power among different printers of even the same technology (and in some cases with the same models but different units) significantly affect the printing settings and the biocompatibility of prints leaving prints with variable uncontrolled uncured monomer.
Too low power printers and too low exposure times may leave too high concentrations of unreacted monomers and extractables, resulting in decreased safety and biocompatibility.
Not all printers meet the quality requirements for printing biocompatible resin systems by SLA, DLP, LCD, and Inkjet printing technologies.Since printers suffer from certain significant variability of light power, since it gradually decays upon time, as well as significant light power variability across the resin tank, affecting the safety, biocompatibility, and quality of 3D printed medical devices.
Polymer conversion (the % of monomer converted to polymer), and the % of uncured monomers and other leachables and extractables depend on the quality, specifications, and reliability of the printer and the light box unit, such as their light power, wavelength, light power distribution across the printing area, etc. Light power decay prevention protocols, including regular calibrations and maintenance need also to be considered when designing and implementing professional printing and postprocessing protocols.
Learn more about the natural gradual decay of light power of 3D printers:
Examples of light power difference* of different LCD & MLCD printers measured with a commercial light meter UV-420 of 400 Euro with a wavelength measuring range 375-475 nm and a maximum peak wavelength at 420 nm.
- Standard multicolor LCD printers:
- Anycubic Photon Zero 0.27/0.30 mW/cm2*
- Longer Orange 30 0.29/0.31 mW/cm2
- Anycubic Photon S 0.43/0.46 mW/cm2
- Monochrome LCD "MLCD" printers:
- Phrozen Sonic Mini 4K: 0.60/0.70 mW/cm2
- Phrozen Sonic Mighty 4K: 0.79/0.93 mW/cm2
- Phrozen XL Mono 4K: 1.05/1.30 mW/cm2*
- Creality LD-002H: 1.40/1.80 mW/cm2
- Anycubic Photon Mono X: 1.70/1.90 mW/cm2
- Commercial mono 4K printer unit 1: 1.05/1.15 mW/cm2
- Commercial mono 4K printer unit 2: 1.10/1.30 mW/cm2
Example of measuring the power of the same unit of Anycubic Photon Mono X with different light meters:
- Anycubic Photon Mono X: 1.70/1.90 mW/cm2 with light meter UV-420 of 400 Euro with with a measuring range of 375-475 nm and a maximum peak wavelength at 420 nm
- Anycubic Photon Mono X: 8.7/7.5 mW/cm2 with a low cost light meter from Chitu Systems of 50 Euro with a measuring range of 402-407 nm and a maximum peak wavelength at 405 nm
- Different commercial light meters provide different readings since not of all of them have the same spectral response range, nor the same maximum peak wavelength, nor have been calibrated with the same light wavelength of the printer (typically 405 nm)
Conclusion
Different printer models and units of even the same printer technology and brand have different light power across the vat for photocuring and printing 3D resins. The centre of the printer has higher light power than the corners and sides. Additionally, light power naturaly decays upon use of the printer.
The different readings of light power measurements with different light meters are relative. This relative measurements need to be adressed since absolute non unconsistent readings are required for providing accurate printing settings for professional printing, especially for getting the traditional "working curve" to select the optimum printing settings for SLA 3D printing and obtain the Critical Energy Ec (mJ/cm2 ) and the Penetration Depth Dp (μm or mm) of the 3D resin. For more info read: Fundamentals of Stereolithography by 3Dresyns
Unless all the mentioned variability issues are prevented and properly addressed the supply of fixed printing settings is not possible since different light meters provide different readings for the same 3D resin system.
This overall variability and unconsistency of light power affects the printing settings, which can be fast & easily overcome with our General Instructions for Use "IFU" for SLA, DLP & LCD printers and with our more Detailed Instructions for Use "IFU" for DLP & LCD printers.
3Dresyns calibration methodology and filling up 3Dresyns curing rate table as shown in our detailed Instructions for Use IFU is the best way to get reliable printing settings of the chosen 3D resin in any printer status.
The curing rate table can be ordered online for 40 Euro per ordered 3D resin. It provides the thickness of the chosen 3D resin cured at a light power similar to your DLP/LCD printer at 405 nm at 5, 10, 15, 20, 25, 50, 75, and 100 seconds.
For getting exact values we recommend you ordering the same light meter as ours, the Chitu Systems Digital UV Light Meter. 3Dresyns has chosen this model due to its affordability and realibility since its spectral range of 402-407 nm coincides with most printers light wavelength (405 nm).
The ordered curing rate table can be much more accurately measured after sharing your exact printer power since this will permit the 3Dresyns team to measure the curing rate table of your ordered 3D resins with the same power as yours, since we will match your light power (light power matching) for fast & easy finding your optimum printing settings.
*Note: power in mW per cm2 across the vat expressed with two values: low value in the corner/high value in the centre of the resin tank to show the power variability across the printing area