Stereolithography (SLA) 3D printing stands as a foundational technology in the additive manufacturing landscape. This method meticulously crafts three-dimensional objects by employing a light source to selectively cure liquid resin. At its core, Stereolithography 3d Printing involves a vat of liquid resin that is exposed to a controlled light source, causing it to solidify layer by layer. Initially, traditional SLA 3D printers directed the light source from above the resin vat. However, a significant advancement came with inverted stereolithography, pioneered in 2011 by Formlabs innovators. This approach ingeniously positions the light source beneath the resin vat, projecting patterns onto the bottom-most layer. As each layer cures, the build platform ascends, allowing fresh liquid resin to flow beneath the newly formed solid layer, thus continuing the build process.
The Innovation of Inverted Stereolithography in 3D Printing
The development of inverted stereolithography marked a turning point in stereolithography 3D printing technology. Several key innovations paved the way for this advancement, notably the creation of the transparent resin tank bottom, which later evolved into flexible designs. This novel tank design was crucial in enabling the construction of larger inverted SLA 3D printers. The flexible surface of the tank effectively mitigated peel forces, a common challenge in traditional SLA processes, allowing for more expansive and reliable builds.
The Material Science of Stereolithography: Resins and Light Curing
Stereolithography 3D printing relies on the fascinating interaction between light and specialized thermoset materials known as resins. These SLA resins are formulated to be light-reactive, undergoing a curing process when exposed to specific wavelengths of light. This exposure triggers a process where short molecular chains within the resin link together. This polymerization process transforms the liquid monomers and oligomers into solid structures, forming geometries that can be either rigid or flexible depending on the resin formulation.
Over the past decade, the landscape of resin 3D printing has expanded significantly, leading to the emergence of various subtypes, each distinguished primarily by the type of light source utilized. These advanced forms of stereolithography 3D printing include laser-powered Stereolithography (SLA), Digital Light Processing (DLP), and Masked Stereolithography (MSLA), the latter often used interchangeably with LCD 3D printing.
A detailed graphic illustrating Formlabs’ Low Force Display™ (LFD) print engine, a sophisticated type of Masked Stereolithography (MSLA) 3D printing technology.
Post-Processing in Stereolithography 3D Printing: From Print to Final Part
Regardless of the light source’s orientation or type, the stereolithography 3D printing workflow includes essential post-processing steps. Once the printing phase is complete, a crucial washing step is required. This typically involves using alcohol or ether to meticulously remove any uncured liquid resin from the surface of the printed part. Following the wash, depending on the specific resin material used, a post-cure step may be necessary. Post-curing further completes the polymerization process, ensuring the part achieves its optimal material properties and performance characteristics. For specialized applications or aesthetic enhancements, further post-processing methods such as coloring, coating, or plating can be employed to refine the final product from stereolithography 3D printing.
