The Printing Process
3. Layer by Layer
The way SLA and FDM parts are built significantly affects their strength. SLA creates parts with generally isotropic properties, meaning the strength is relatively consistent in all directions. This is because the resin layers are chemically bonded together during the curing process, creating a more uniform and solid structure.
FDM, however, typically produces parts with anisotropic properties. This means the strength varies depending on the direction of force. The layers are fused together thermally, which can sometimes result in weaker bonds between layers, especially perpendicular to the printing direction. Imagine trying to snap a stack of pancakes — it's much easier than snapping a solid pancake. That's similar to how FDM layers can sometimes behave.
The infill density, or the amount of material inside the part, also plays a critical role. A higher infill density (more plastic inside) generally results in a stronger part, regardless of the printing method. However, even with high infill, FDM parts can still be more prone to layer separation under stress compared to SLA parts.
Proper print settings are crucial. For FDM, ensuring optimal nozzle temperature and bed adhesion can greatly improve layer bonding. For SLA, precise laser power and exposure times are necessary for proper resin curing. Messing these settings can result in parts that are weak and brittle, or that fail during the printing process. So, attention to detail is key!
