Meaning
Liquid materials undergo a chemical reaction to become solid when they are exposed to specific wavelengths of light. In additive manufacturing, photopolymer resin is the primary feedstock for processes such as stereolithography and digital light processing. These liquids contain monomers and photoinitiators that react to ultraviolet light to form a cross-linked polymer network.
This allows for the creation of high-resolution parts with smooth surfaces and complex internal geometries that are impossible to achieve with traditional molding.
Curing Mechanism
Speed of the solidifying process depends on the intensity of the light source and the concentration of the initiators. As the photopolymer resin hardens, it can experience slight shrinkage that affects the final dimensions of the part. Engineers must compensate for this in the design phase to ensure the finished component fits its intended assembly.
Polymer Strength
Final properties of the material are determined by the chemical structure of the monomers and the degree of cross-linking. Some types of photopolymer resin are designed to be rigid and brittle, while others are flexible or resistant to high temperatures. Post-curing the parts in a dedicated UV oven ensures that the chemical reaction is complete and the material reaches its full mechanical potential.
Viscosity Control
Ease of printing is affected by how easily the liquid flows across the build platform. If a photopolymer resin is too thick, it may not level correctly between layers, leading to defects in the finished part. Heating the resin tank is a common way to maintain a consistent flow rate during long production runs.
