Both are industrial-grade large-size 3D printers. Why is there a huge price difference between SLA models and FDM models? The answer is of course that compared to FDM industrial-grade 3D printers, the more expensive industrial-grade SLA printers have more advantages in terms of printing speed and molding accuracy. Next, let’s take a look at the most critical differences between these two types of models.
1. Basic principles
FDM, “fused deposition” technology, uses a heating device to heat and melt filaments such as ABS and PLA, and then squeezes them out through an extrusion head like toothpaste, stacking them layer by layer, and finally forming them. Its mechanical system mainly includes five parts: nozzle, wire feeding mechanism, motion mechanism, heating studio, and workbench. The materials used in the fused deposition process are divided into two parts: one is the molding material, and the other is the support material.
SLA, “stereolithography”, the laser beam outlines the first layer of the object on the surface of the liquid photosensitive resin, and then the production platform drops a certain distance, and then the solidified layer is immersed in the liquid resin, and this is repeated until the printing is formed. Finally, after the prototype is taken out of the resin, it is cured and then polished, electroplated, spray painted, or colored to obtain the required product.
2. Forming space
FDM 3D printers are flexible and diverse in structure, including XYZ frame structure, delta structure, and robotic arm. Therefore, the forming space can be made very small or very large. However, the mechanical structure of large-size FDM models often has problems such as poor stability and slow printing speed, making it difficult to meet users’ long-term printing needs.
SLA is the earliest rapid prototyping manufacturing process. It is printed by moving the optical axis. In theory, it can also be made into large sizes. However, since the SLA industrial model uses a forward-swinging resin tank, the depth of the resin tank must be the same as the height of the workpiece, and the molding space must be filled with resin material, which also means that the equipment must be very large. At the same time, every time the material is changed, the entire material tank must be emptied.
3. Printing accuracy
The FDM model obtains parts by extruding molten materials layer by layer through a nozzle. The finished product has an obvious step effect (surface texture) and is not suitable for building large parts. In addition, theoretically, the smaller the diameter of the nozzle of an FDM model, the higher the accuracy. However, a small nozzle can easily cause clogging of consumables, so the smaller the nozzle, the better.
The SLA industrial model uses laser solidification molding, which has an insurmountable advantage in accuracy over the FDM model. For example, Jiguang Erwo’s industrial-grade SLA model can produce a layer thickness as accurate as 0.05mm, and the surface quality of general-purpose photosensitive resin materials is smooth and easy to post-process. It can produce various precision parts and assemblies with complex structures.
4. Printing supplies
FDM machines are now relatively popular, and the consumables are relatively cheap, mainly including PLA, ABS, TPE, TPU, etc. Among them, PLA is a biodegradable thermoplastic that does not produce a bad smell when printing, so it is relatively safe and suitable for use in offices, classrooms, and homes. ABS is a thermoplastic polymer material with high strength, good toughness, and ease of process and form. Its melting point is higher than that of PLA. The platform must be heated during printing to avoid warping and shrinkage of consumables due to excessive cooling. TPE/TPU flexible materials can make objects with particularly good stretchability. However, printing is more difficult, especially for remote-feeding 3D printers, where it is difficult to control the advancement and retreat of flexible materials.
SLA model consumables are liquid photosensitive resin, which has the characteristics of fast curing, high molding accuracy, good surface effect, and easy post-processing. It is suitable for the production of prototypes of automobiles, medical equipment, electronic products, architectural models, etc. It should be noted that photosensitive resin has odor and toxicity and needs to be sealed. At the same time, to prevent premature polymerization, it needs to be protected from light.
FDM industrial equipment mainly involves mechanism movement and control. Relatively speaking, the technical threshold and cost are low. In addition, the utilization efficiency of raw materials is high and there is no pollution from poisonous gas or chemical substances, which greatly reduces the molding cost. The technical threshold for SLA industrial equipment is relatively high. There are relatively few equipment manufacturers but relatively strong capabilities. One piece of industrial equipment costs between 300,000 and several million. Although the price difference between the two is several times, it is still very worthwhile for companies that require high-precision module manufacturing.
