Stereolithography (SLA) is one of the earliest and most widely used 3D printing technologies.
It uses a laser to cure liquid photopolymer resin into solid layers to create three-dimensional objects. This technology is known forits high precision and smooth surface finish, making it useful in industries such as engineering, medical modeling, and product design.
Working Principle of Stereolithography (SLA)
The working principle of Stereolithography is based on photopolymerization, where liquid resin is hardened using ultraviolet (UV) light to form solid layers. In this process, a 3D object is created layer by layer until the final shape is completed.
First, a tank is filled with a special liquid photopolymer resin that can harden when exposed to UV light. A computer-generated 3D model of the object is then prepared using design software and sent to the printer.
Inside the printer, a UV laser traces the cross-section of the object on the surface of the liquid resin. The laser light cures or solidifies the resin wherever it touches, forming a thin solid layer.
After one layer is completed, the build platform moves slightly, allowing a new layer of liquid resin to cover the previous one. The laser again scans the next cross-section of the object and solidifies the resin. This process is repeated many times, building the object layer by layer from the bottom up.
Once the printing process is finished, the object is removed from the resin tank and usually cleaned and cured further under UV light to improve its strength and stability.
Thus, stereolithography converts a digital 3D design into a physical object by selectively curing liquid resin with a UV laser layer by layer.
Types of Resin Materials Used in SLA Printing
In Stereolithography, different types of photopolymer resins are used depending on the required properties such as strength, flexibility, appearance, or safety. Each resin type is carefully selected to match the specific demands of the application — from visual prototypes to functional end-use parts.
1. Standard Resin (ABS)
Standard resin is mainly used for visual models and prototypes where appearance is important. It provides a smooth surface finish and high detail.
Common color: White
This resin is often used for form and fit testing and product visualization.
2. Engineering Grade Resin
Engineering resins are designed for functional parts that require mechanical strength and durability.
Examples include:
- Tough 1500 (PP-like) – Good impact resistance and flexibility.
- Tough 2000 (ABS-like) – Strong and rigid, similar to ABS plastic.
- Flexible 50A – Soft and rubber-like material.
- Flexible 80A (Clear) – More flexible but slightly firmer than 50A.
These materials are commonly used for mechanical prototypes and functional testing.
3. Special Resins
Special resins are developed for specific industrial requirements.
Examples:
- Fire Retardant Resin – Resistant to flames and high temperatures.
- Silicone 40A – Very flexible material used for soft parts.
- Clear Resin
- High Temperature Resin
4. Biocompatible Resin
Biocompatible resins are safe for medical use and can come in contact with the human body.
They are commonly used in dental models, surgical guides, and medical devices.
Specifications of SLA Printer
The performance of an SLA printer is defined by several technical specifications that determine the accuracy, speed, and quality of the printed object.
Build Volume
Build volume is the maximum size of the object that can be printed in a single job. Our SLA technology Mars Pro-850 comes with a build volume of 850*850*500mm, designed to perform in a 24/7 production environment. But depending on the design, we can print a maximum of 1100mm.
Layer Thickness
Layer thickness refers to the height of each printed layer. Typical SLA printers have a layer thickness of 25–100 microns, which allows very fine and detailed printing. This precision ensures consistent output quality across a wide range of complex geometries and part sizes.