Post-processing is an essential part of resin 3D-printing. Printed parts need to be cleaned, dried and post-cured. The washing and drying steps are explained at the support article ‘how to post process SLA, DLP & LCD printed objects’. The next step that follows is post-curing.
Post-curing of 3D-printed parts
Post-processing is necessary to get the optimal properties out of your prints. If you use a stereolithography (SLA) 3D printer or a digital light processing (DLP) 3D printer, including LCD projectors, it’s essential to know how to post-process. Post-curing is an important post-process step.
During 3D-printing, the resin is polymerized to a degree that it has exact dimensions and is solid enough to withstand peeling forces. This means it has reached a polymerization degree of 50 to 85%, depending on the resin and type of 3D-printer. Usually the best physical and mechanical properties are reached with a polymerization degree of > 95%, meaning that the printed parts have not reached their full potential and need some extra UV-light and/or temperature to get there.
This curing test was performed with the Wicked CUREbox, which has 4 x 9 watt light output in the form of 365nm and 405nm LED’s. Time and temperature are the two variables to set. The following list of post-curing settings were selected as recommended settings for Liqcreate resins:
Two different post-curing settings were selected for Strong-X. A shorter curing cycle of 30 minutes at 60 degrees Celsius for general and engineering applications that don’t require the high temperature resistance and a longer curing cycle of 120 minutes at 60 degrees Celsius for high-temperature applications. This long cycle will increase the temperature resistance of Strong-X, and also makes the product slightly more brittle, which might limit the usage for general engineering applications.
All resins suffer from oxygen inhibition, which means that oxygen will have a negative effect on the curing. This can result in surface stickiness. To avoid stickiness it is important that parts are properly washed and processed, more information about the processing of printed parts can be found here. Flexible-X is in general sensitive to this effect and is therefore advised to be cured in an oxygen free environment. This can either be done to post-cure parts in a water- or glycerol bath or cure the parts under a nitrogen flow.
Longer post-cure times or higher post-cure temperatures can lead to more brittle end-products, especially for tough and flexible materials like Clear Impact, Tough-X and Flexible-X this would be an unwanted effect.
If mechanical properties are important for your project, it is not recommend to undercure the parts, or use undefined curing methods like sunlight curing. Undercured parts have the tendency to be softer, weaker and properties might change over time. Curing with undefined methods like sunlight will likely give variable results due to the variable amount of UV-light and temperature on the 3D-printed parts. Many curing boxes devoted to 3D printing, like the Wicked CUREbox, are compatible with Liqcreate resins. Before using a curing box, please check the settings (light intensity, temperature capabilities etc.).
All that remains is to wish you good luck with the post-curing of your 3D object. If there are any questions, please contact Liqcreate: firstname.lastname@example.org.