Testing standards: Effect of printer and printing specifications on results
The typical properties of our made to order 3Dresyns are tested with the following standards:
The properties of our made to order 3Dresyns are tested with the following standards:
- Tensile strength at yield and ultimate ISO 527-2
- Young´s modulus ISO 527-2
- % Elongation at yield and ultimate ISO 527-2
- Flexural strength at yield and ultimate ISO 178
- Shore hardness ISO 868
- Deflection Temperature HDT@45 ISO 75
Our biocompatible 3D resins for biomedical, orthodontic and dental applications have been developed, evaluated and passed the quality requirements of ISO 10993-1, ISO 7405 and ISO 18562-1-4 after have been properly printed and postprocessed with the appropriate printer and postprocessing units, instrumentation, processes and protocols. Nevertheless, medical device manufacturers are responsible of certifying their medical devices since the quality and biocompatibility of a medical device depends significantly of the printing and postprocessing specifications, which are beyond the control and responsibility of any 3D resin supplier. For more info read: About Certification of biomedical devices and food packaging
Biocompatible 3D resin testings
- Ultimate flexural strength ISO 20795-1
- Young´s or Flexural modulus ISO 20795-1
- Sorption ISO 20795-1
- Solubility ISO 20795-1
- Residual monomer ISO 20795-1
- Biocompatibility: cytotoxicity ISO 10993-1
- Biocompatibility: mutagenicity ISO 10993-1
- Biocompatibility: erythema or edema reactions ISO 10993-1
- Biocompatibility: sensitizer ISO 10993-1
- Biocompatibility: systemic toxicity ISO 10993-1
About biocompatibility and mechanical properties
Photopolymer 3D resins are photoreactive resin systems, which depending on their design, the functional additives used, the degree of cure (% conversion from monomer to polymer), the postcuring and cleaning process used for removing residuals and byproducts, can have increased or decreased biocompatibility and mechanical properties.
Their overall results can vary significantly because depend on the final 3D resin tuning or customisation to different printing, postcuring and post processing specifications, which affect the overall biocompatibility and performance properties of printed materials.
Photopolymer 3D resins cannot be considered finished materials, such as conventional plastics or polymers, because their biocompatibility and functionality "performance" depend on their tuning, adjustment, or customisation to the specifications of the chosen printing setup. The degree of cure and cleansing of any residuals and reaction byproducts, depend significantly on the printer power, the postcuring, cleansing and overall post processing specifications and protocols.
Different printers have different specifications, such as light wavelength (365, 385 and the most commonly used 405 nm) and light power across the resin tank, which can range from 0.3 to 50 mW/cm2, or even higher depending on the chosen SLA, DLP, LCD or Inkjet printer.
Our made to order 3D resins require the use of different dosage of our photo accelerant Fine Tuners FT for printing them with printers having different light wavelengths and power. Depending on the dosage of photo acelerant and other functional additives and colors, higher or lower printing speed, resolution, mechanical properties and biocompatiblity can be achieved.
Due to the different printing specifications, or setups variability, 3D resin customisation for each printer setup is required for maximum biocompatibility and overall performance.
As example, our made to order multifunctional 3Dresyns for different printers may have different rheology / viscosity and mechanical properties for each particular product reference (not for different lots of the same final SKU). This is the reason for not disclosing all the properties specifications as fixed values, such as the viscosity of some 3D resins because the final dosages of our Fine Tuners and functional additives can affect the viscosity as well as other properties, such as light fastness (yellowing), biocompatibility and mechanical properties.
About the "typical" properties of 3D resins
The physical and mechanical properties of our products are reported in ranges, or with threshold values with below "<" and above ">" symbols:
- range values reflect the interval of certain property values which are true, and above or below the interval or range it is not
- threshold values with below symbol "<" reflect the level, point, or value below which certain property value is true and above which it is not
- threshold values with above symbol ">" reflect the level, point, or value above which certain property value is true and below which it is not
There are several reasons for using ranges (intervals) and threshold values. The physical and mechanical properties depend on the chosen printing speed, relative viscosity version, color, functional additives, as well as on the printer and printing specifications, such as:
- Power difference of different LCD & MLCD printers and its consequences
- Do you want to go in depth? Let´s unlock the black box!
- Key variables affecting mechanical performance of 3D prints
- Tg, HDT, and mechanical properties depend on printing specifications
The physical properties of our 3Dresyns are not fixed, nor absolute, because depend on few variables. Depending on the specific property values are either shown in value ranges, or with values above ">" or below "<" certain x units since our published data reflects typical and achievable property values which in practice exhibit certain variability depending on the chosen SLA, DLP and LCD printer and printing settings, the postcuring and postprocessing conditions:
- low power printers, such as LCD and DLP printers, tend to yield:
- superior mechanical properties (lower brittleness), relatively higher elongation and lower rigidity "Young´s modulus" and HDT than higher power printers, such as laser printers.
- very high power printers, such as strong laser printers eg Formlabs Form 2 & 3, tend to yield:
- inferior mechanical properties (brittleness), lower elongation, and higher rigidity "Young´s modulus" and HDT than lower power printers, such as LCD printers.
- Discover some of our consulting services for choosing the best printer setup for your specific needs
- for any 3D resin, cleansing, postcuring and postprocessing conditions affect the resulting overall performance properties. Read our Instructions For Use IFU
- Overall biocompatibility and mechanical results can be significantly affected by the sum of certain known variables, as well as by certain unknown, or not easily identifiable variables. For more info read about the importance of using safe biocompatible 3D resins:
- Printing power
- ultra high intensity printing as the used in SLA laser based printers, such as Formlabs tend to increase brittleness versus relatively lower intensity printing specifications, as the used in DLP and LCD printers (at the same energy dose), as well as other properties, such as rigidity "Young´s modulus" and HDT. For more info read: Tg and HDT of 3D resins
- Printing orientation
- vertical, horizontal, and different angle printing of dog bones and bars for testing eg elongation, tensile and flexural strengths provide significantly different quantitative values due to anisotropy since 3D printed materials are typically printed layer by layer exhibiting lower or higher interlayer weakness and mechanical properties in the X, Y and Z directions. For more info read these papers:
- Cleaning chemicals
- the use of isopropanol IPA reduces significantly the mechanical properties of most materials, weakening and making them fragile: discover our processing auxiliaries and cleaning products for cleansing 3D prints
- Read: comparison of different methods for cleaning and post processing 3D printed resins
- Postcuring specifications
- wavelength, power, dry or by dipping, with or without O2, postcuring time, etc, affect the degree of cure and the biocompatibility
- a too short postcuring can decrease biocompatibility
- an excessive postcuring cycle can cause excessive yellowing and brittleness
- learn more about how the:
"curing process generally reduces the plasticity of the resins (Formlabs), causing a more or less marked brittle behaviour. This represents a potential limitation to the use of SLA 3D printing for structural elements which require some plasticity to avoid dangerous sudden failures", as demmostrated in this paper: Material Property-Manufacturing Process Optimization for Form 2 Vat-Photo Polymerization 3D PrintersLearn more about biocompatibility of medical devices:
We provide consulting for biomedical devices and the following analytical services, which can be contracted for helping you to design the right material for your specifications.
If you need support for designing your optimum printer setup discover our consulting services