Stereolithography (SLA) 3D printing stands as a pioneering additive manufacturing technology, utilizing light to solidify liquid resin into precise three-dimensional forms. The fundamental process involves directing a light source onto a vat of liquid resin, causing it to harden layer by layer. Initially, traditional SLA 3D printers employed a top-down approach, positioning the light source above the resin vat. However, a significant advancement emerged with inverted stereolithography, conceived in 2011 by Formlabs’ innovators Max Lobovsky, David Cranor, and Natan Linder. This inverted method strategically places the light source beneath the resin vat. The desired cross-section is then projected onto the bottom layer of resin, and as the build platform ascends, liquid resin seamlessly refills beneath the newly solidified layer.
Representation of Formlabs’ Low Force Display print engine showcasing advanced MSLA 3D printing.
The advent of inverted stereolithography was propelled by crucial innovations, notably the development of transparent and subsequently flexible bottomed resin tanks. This novel tank design was instrumental in enabling the creation of larger inverted SLA 3D printers. The flexibility inherent in the tank surface effectively mitigated peel forces, a common challenge in earlier SLA iterations.
At the heart of Sla 3d Printing lies the utilization of light-reactive thermoset materials known as resins. These specialized SLA resins undergo a transformative process when exposed to specific wavelengths of light. Short molecular chains within the resin link together, initiating polymerization. This process converts monomers and oligomers into robust, solidified structures, capable of achieving both rigid and flexible geometries depending on the resin formulation used.
Over the past decade, the landscape of resin 3D printing has expanded significantly, giving rise to various refined processes. These advancements are primarily distinguished by the type of light source employed. Notable variations include laser-powered stereolithography (SLA), digital light processing (DLP), and masked stereolithography (MSLA), the latter often used interchangeably with LCD 3D printing. Each method leverages light in a unique way to achieve precise resin curing.
Regardless of the light source’s orientation or specific type, the core SLA 3D printing workflow remains consistent and relatively straightforward. Upon completion of the printing phase, a crucial washing step is necessary. This typically involves using alcohol or ether to meticulously remove any residual liquid resin from the surface of the newly formed part. Following the washing stage, a post-curing process might be required, contingent on the material properties of the resin. Post-curing ensures the complete polymerization of the part, enabling it to attain its optimal mechanical characteristics. To further enhance the part’s functionality or aesthetic appeal, additional post-processing techniques can be employed, such as coloring, coating, or plating, tailored to specific applications and desired finishes.
