3D printing or additive manufacturing is a common name for a number of different printing technologies. One of them, that is becoming more and more popular is resin printing. And no wonder, it has high-resolution, it’s fast, and the finished results look great.
In this article, we will look into resin printing technologies.
How resin printing works?
Resin printing is a 3D printing technology that uses UV 405nm light source to cure photopolymer liquid resin building 3D solid object without visible layer separation.
Nowadays resin printing can be separated into three main technologies:
Digital light processing (DLP) – 3D printing technology that uses a projector to flash (with UV light) an image of a layer across the entire printing platform that way curing photopolymer resin on all flashed surfaces simultaneously. The image is created in a matrix on a semiconductor chip – Digital Micromirror Device (DMD). This chip consists of microscopically small mirrors and each mirror represents one or more pixels of the flashed image. DLP printer printing resolution can vary – usually, the bigger is a printing volume the lower resolution it delivers. Of course, by increasing projectors quantity and quality much better results can be achieved for big volume printing but that greatly increases costs. But even with 4k resolution projectors quality of DLP is slightly lower than of SLA – because of projector pixels that create staircase effect (Voxel effect), but with anti-aliasing and pixel shifting corrections this effect can be minimized. DLP 3D printers cost vary from $500 to $10000+ for high-end industrial size models.
Stereolithography (SLA or SL) is one of the oldest 3D printing technologies. Sometimes SLA term is used for resin 3D printing in general but it is not exactly correct. Basically, SLA is a 3D printing technology that uses UV laser as its UV light source to cure photopolymer resin. Considered as most precise but also very expensive (for example Formalabs Form 3 cost ~$3500) and slower than the other two resin printing technologies. It is slower because the UV laser must tracepoint to point the entire geometry accordingly to computer-aided design of-course tracing speed can be increased but in cost of quality. You should also consider the SLA printer complex architecture – maintenance can be costly and might require professional intervention if the laser or any of the optics fails.
Masked Stereolithography (MSLA) – 3D printing technology that uses UV LED matrix as a light source and LCD display as a mask to hide build plate parts that should not be cured. Very cheap and new user-friendly technology – that can print on all build plate at once – fast and reliable but not so precise as stereolithography because MSLA quality is proportional to masking display resolution – as result we get tiny pixels (yes, same as with DLP technology) that usually cannot be seen with the naked eye –magnifying glass is needed to see them on the newest 2k or even 4k monochrome displays (especially with antialiasing option on). Monochrome displays were introduced in 2020; they make MSLA printing more reliable (longer live time) and much faster (3-4 times) than previous LCD displays. The cost of a new monochrome MSLA printer starts from $250 up to $1500+ depending on build quality and manufacturer. The main disadvantage of this printing technology is a small printing volume.
Common for resin printer technologies:
- UV light source is required with a spectrum usually between 380-410 nm;
- Print with special liquid resin;
- “Messy “post-processing is required – parts must be washed in a special solvent (depends on used resin) to remove the excess uncured resin. If parts are printed with supports after printing it is necessary to remove all supports and then all prints must be additionally cured.
Which technology is better there is no straight answer – choose the one that better corresponds to your needs.
If accuracy and resolution of the printed model is your main goal then you might choose SLA, but considering that DLP and MSLA printing quality has grown and 25 microns resolutions can be archived on consumer-level printers and even voxel effect can be minimized (antialiasing) –you might better look for DLP or MSLA as they print much faster.
DLP and MSLA are pretty similar technologies (both print whole level at once and both have voxel effect). DLP is a better option for larger printing volumes and MSLA is the best option if you are looking for small part printing like DnD miniatures.
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