SLA (Stereolithography) is a 3d printing method that makes use of curable photopolymer such as a liquid resin which hardens when UV Light is focused. The SLA Printing process involves building the models upside-down and the build platform lifts the model upwards, out of the resin bath. The Laser light hardens each layer of resin as the entire image of one layer is projected onto the resin. Most SLA printers use laser but also there are others that uses a digital projector as an alternate to harden the resin.
SLA printers use a specific type of resin materials that are durable or highly specialized, for instance, can be used for dental, heat-resistant, or flexible for industrial uses. However, Resins are limiting when it comes to colour as they don’t offer varieties of colours compared to FDM Printers.
A Bottle of Resin Material is sold in 1 Litre and this amount can enable 120 to 140 tabletop figurines or minis to be 3D printed or for instance, 500 cubes with 1cm x 1cm dimension can be printed with 1000ml resin quantity, larger models could use 100ml of resin.Slicing software such as CHITUBOX or Lychee Slicer gives information on the exact resin quantity required for a print, after importing an STL File.For a regular basis, 500ml of resin can last around 2 weeks to a month depending on the orientation of the model, the number of supports, the scale/size of the model, your success/failure rate and 1 litre of resin can last 5 days to 1 month and this depends on the layer height set for printing as a 0.025mm layer height is going to need twice as many layers as a 0.05mm you are using for your 3D object designs Depending on the orientation of the model, the number of supports, the scale/size of the model, your success/failure rate, 500ml of resin can last you a month or so, or just a few days. When you work out the amount of resin you’ll use for one print, you take 1000ml and divide the number of ml for the print.
SLA Printers have higher resolution when it comes to printing compared to FDM Printers. As for SLA factors such as optical spot size, either the laser focus or the projector’s pixels determine the printing resolution. The level of force applied by the machine also enhances the resolution as it applies lighter force when printing the layers which result in smoother surfaces .
Layers are built differently in SLA Printers as part printed at 100-micron layers on an FDM printer looks vastly different from a part printed at 100-micron layers on an SLA printer,hence FDM requires lower layer height compared to SLA to achieve a great resolution and would also take 2 to 4 times longer to print.
CAD software or 3D scanned Data is used to produce o 3D Model of a design. This is then followed by STL OR OBJ file export from the CAD software whereby it is imported into a slicing software which slices the 3d model into layers for printing.
.SLA printer requires continuous printing setting adjustment to achieve a successful print and the settings will change for every new design. Print preparation tools such as PreForm, CHITUBOX etc can be used to facilitate the process.
once the 3D printers are turned on, they can run without human intervention and some of the SLA printers provide a cartridge system, that refills the material automatically.
Post-processing is applied as the last step to a finished ready-to-use object. The process involves rinsing the 3d printed parts in isopropyl alcohol (IPA) or alternative solvents to remove any uncured resin from their surface. Recently this process can be automated by professional solutions such as Form Wash whereby the Parts can be transferred directly from the printer to Form Wash, which agitates the solvent around the parts to clean them and automatically raises the 3D printed parts out of the alcohol bath when the process is complete. After pat dry, some optional process with some resin materials is post-curing, which adds strength and stability to the printed parts.
SLA printer is challenging as apart from the resin consumption, the resin tank has to be replaced every after 2-3 litres of resin use and this is because the light source is hindered as the inside tank gets smudged over time, so the images cant be precisely projected in the resin. Resin tanks will lead loss of $20 to $80 for maintenance. Moreover, Resin is expensive as 1 litre of standard resin will set you back around $40 to $150.