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 |  Sammy Ekaran

The Difference between FDM, DLP and SLA Technologies

Fused Deposition Modeling FDM

FDM stands for Fused Deposition Modeling, which means that the material is being deposited in layers that fuse together to create a 3D object after the deposition is finished and cooled. Slicing software processes imported 3D model (most frequently .stl), slices this into layers and generates a GCode which tells the printer where and how to move, a GCode is also in charge of such parameters as speed and temperature of printing. With the help of SelfCAD inbuilt slicer, there’s now no need to switch between different programs! After the GCode is ready it is sent to the printer. The heated melted filament is spread through the nozzle layer by layer until the object is complete.

FDM technology is most commonly used in hobby 3D printing, as it is quite simple and this allows producing cheap 3D printers. Nevertheless, FDM technology has some limitations which may cause printing problems. It is very important to handle the calibration and printing settings to get really what you want from a cheap FDM 3D printer.

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Image SRC: The Complete Guide to Fused Deposition Modeling (FDM) in 3D Printing

Stereolithography Apparatus (SLA)

A 3D printing technology works by curing resin with light and builds objects layer by layer, which makes it another type of additive manufacturing. It was first invented in the 1980s. The process of solidifying a liquid resin by light is called photo-polymerization. SLA printers usually build the models from top to bottom, the build platform lifts the model upwards, out of the resin bath. SLA is considered one of the most accurate forms of 3D printing.

There are two main types of SLA Technology: laser-based (abbreviated as SLA) or projection based (DLP for Digital Light Projection). Lasers „draw“ the layers; in DLP, an entire slice (a two-dimensional layer) of the model is projected at once into the resin bath. Laser SLA printers have the small surface of the laser beam and are normally slower than DLP models. 3D objects printed using DLP technology have the least visible layers.   


FDM printers use PLA, PETG, or ABS filament, made of solid polymer or polymer blended with other materials (such as wood, ceramics). You can read our guide and choose wisely which filament to use. Filaments are available in various colors and most FDM printers can use standard filament rolls that are available in two standardized sizes (diameter: 1.75 or 2.85mm). When it comes to SLA printers, their owners are limited in resin materials and their colors.

FDM technology is extrusion-based and the precision and smoothness are affected by such factors as the temperature of printing and the size of the layer. As the weight of upper layers squeezes the previous layer down, it may cause numerous printing issues, such as misalignment of layers, shifting of layers, over extrusion, rounding on corners, etc. SLA printers produce higher-resolution objects. The resolution is determined by the optical spot size of the laser (or a projector in DLP technology) and there’s no physical pressure generated by the upper layer, so the 3D model created online has a very smooth finish. With high-resolution SLA printers are able to print very detailedly, textured objects which may never be the printer with FDM printer.

As for the price, the FDM printer will be a far more affordable solution compared to the SLA printer and resin refills. The components of the printers themselves are also very different when it comes to price. FDM printers parts are affordable and the variety is huge, you can even print the parts yourself (which is a common practice). The components for SLA printers are more expensive and very often are proprietary and cannot be exchanged between different printers.

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