The Tech Powering 3D Printers

Although there are numerous types of printers, from the home made, budget machines to the industrial $100k+ machines, two of the most popular technologies used in 3D printing are currently FDM and SLA. On the surface, they yield similar results, so what is the true difference between them and which wins in the battle of FDM vs SLA?

First of All, What is FDM?

FDM stands for fused deposition modeling, which simply means that during printing, the material is deposited in layers to create a 3D printed object. The process utilizes a plastic filament fed through a hot extrusion head where the material is melted and deposited by drawing plastic lines on top of previous layers. FDM printing is one of the most widely used forms of 3D printing, especially for home use, because the printers often come at a low price point. Unfortunately, the bonding force of FDM type printers often leads to layer separation of the resulting prints: compromising resolution and surface smoothness. In addition, when the diameter of the extruded plastic line is getting smaller for more detailed work, the printing speed is drastically hampered.

So How Does SLA Printing Differ?

SLA stands for stereolithography. In this method, full layers of resin are applied at once and then cured using a UV light pattern generator. It is one of the most accurate forms of 3D printing and produces higher resolution objects than FDM because the resolution is primarily determined from the optical spot size of the digital pattern generator, which can be very small.  In addition, there is much less force involved than FDM during layer formation and stacking so the surface is much smoother. Basically the result is that the printed objects look more professional than with FDM printers. SLA has yet to be adequately popularized, due to the higher costs associated with purchasing, maintaining, and supplying the printing material for these units.

Are There Different Types of SLA Printers?

There sure are; laser and DLP.

Conventional laser scanning SLA technology uses an UV laser and two actuated mirrors to project images onto the resin, similar to what you might see in a laser show at a concert. These lasers are used to cure the resin, but can be slow due to small surface area of the point-like light beam.

DLP SLA technology, on the other hand, uses a DLP projector to project images onto the resin in a two dimensional fashion. Therefore, time required to solidify a layer is shorter, and there are less moving parts in the printer too, reducing the chance for required maintenance. The DLP projector is a matured consumer product so it is much more reliable and easier to maintain than a customized laser scanning system that requires sophisticated alignment and calibrations. Above all, by projecting the images to a smaller area, DLP can print models with much higher resolutions that laser scanning cannot achieve.