Resin Printing
3D printing with resin is achieved through curing a liquid resin layer by layer through various methods of applying ultraviolet (UV) light through a clear bottom of a vat. This method of 3D printing offers several advantages such as precise resolution, acrylic resin feel, smooth surfaces, true transparency, and uniform strength.
Materials
Plant Based Resin
Plant based resin made from soybeans that offer a precise, BPA-free and biodegradable model. Plant based resin typically benefits from rapid prints, improved printing environment factors, high accuracy, low model shrinkage, and environmentally friendly products. Great choice for models and displays in a controlled environment (not left outside)
Standard Resin
A good, middle of the road resin material, designed to offer model longevity, reasonable strength, smooth finishes, and precision at a good price. Standard resin models are great for figurines, models, prototypes (non-stress induced), and any other precision print to last.
ABS Like Resin
A strong, yet precise option for models which require resilience to linear and torsional stress with low deformation. ABS like resin models are suggested for any models with a mechanical or stress induced use, however it is important to remember it is still an acrylic resin. ABS like resin is as precise and smooth as other types, however is typically more expensive and takes longer to print.
Thermal deformation at 80 Deg C / Flex Modulus of 1.882 - 2.835 Mpa / Bending Strength 40 - 70 Mpa / Tensile Strength 30 - 53 Mpa / Tensile Modulus of 1.779 - 2.385 Mpa / Shore Hardness of 75D / Notch impact strength 41 - 48 j/m
Quality
Environment
3D resin prints are affected by environmental factors such as temperature and UV radiation. Low temperatures prevent the initial layers or normal layers from hardening completely under standard UV exposure times and cause layer separation and fails the print. Excessive UV radiation causes resin to harden prematurely and causes print errors with debris and hardened surfaces.
Our printers are kept in environmentally controlled conditions within operating temperatures and low ultraviolet interference.
Environmental safety concerns are a factor for resin printer operators as the liquid fumes are toxic in unventilated conditions and may cause skin irritation on contact. We use resin masks with charcoal filters and disposable medical gloves for protection.
Hardware
Our printers are designed for small to medium sized prints with extreme accuracy. The build area for our printers is 5.2" x 3.14” x 6.5” and expose layers to UV radiation using 4k LCD screens. We use flexible build plates to allow for easy separation without the use of tools, eliminating tool scarring on the bottom of prints.
Settings
The main settings when considering 3D resin printing are the bottom exposure time and normal exposure time. Bottom exposure time is the time, elapsed in seconds, which UV radiation is exposed to the resin in the shape of the model layer specifically to harden onto the build plate, this setting is critical to maintain print adhesion to the build plate. The normal exposure time is the time, elapsed in seconds, which UV radiation is exposed to the resin in the shape of the model layer specifically to harden to the previous layer. Bottom exposure times are typically 30 - 160 seconds each and normal exposure times are typically 1.5 - 8 seconds each depending on several factors including resin type and shape of print.
Post Processing
Alcohol Wash
Due to the nature of 3D resin printing, all models need to undergo a wash to remove excess resin. This wash is typically performed using a high percentage isopropyl alcohol, 95% - 99%, with an exception of some water-wash resins. We use automatic wash stations that submerge the print in the alcohol and create a vortex using a magnet driven submerged fan. This insures a complete and consistent wash of the print. Wash times are based on the size and complexity of the print and may vary from 10 minutes to an hour. All of our wash stations are protected with UV blockers to eliminate exposure to UV radiation.
Curing
All 3D resin prints must go through a post curing to ensure complete hardening of the model. This is accomplished using a rotating curing station that submerges the print in UV radiation on all sides with UV towers. UV curing times vary based on the size and complexity of the print and may last between 20 minutes to an hour. Our UV curing process is designed to cure the models evenly and avoid over-exposure.
Sanding
3D resin prints are very receptive to sanding and can be further smoothened using sanding techniques. It is suggested to sand 3D prints in sections and from a course to fine gradient, based on the needs of the sanding. Sanding the resin will dull the outside and should be cleaned and clear coated to bring back the shine and translucence.
Paint and Coat
A base grey 3D resin retains paint well and is used for models which are painted by hand. Sanding the model before painting may allow for better paint retention, however, is typically unnecessary. Clear and translucent 3D resin prints have better interior clarity using a UV protecting clear coat. All 3D resin prints should have a UV protection coating to ensure longevity.