Resin vs. Filament 3D Printer: Which is Best for You?

Stereolithography (SLA) is the oldest form of 3D printing. It works by exposing a layer of photosensitive liquid resin to a UV-laser beam; the resin then hardens in the desired pattern, and the object is built layer by layer until it is complete. This allows you to print a model with extremely fine detail.

Objects printed by SLA 3D printers have smooth surfaces, but often the quality depends upon the printer type. SLA resin printers tend to have smaller build plates, so you can't make larger pieces on them. Printing via SLA involves a longer process as printed objects need to be rinsed using a solvent and then put into an ultraviolet oven to complete processing.

Digital Light Processing (DLP) is the fastest of all 3D printing methods. A layer of hardened material can be printed in a few seconds and quickly transferred to allow for printing of the next layer. Like SLA, DLP 3D printers use liquid plastic resin, but instead of a UV-laser beam, the resin is melted with arc lamps. This light source causes the impressive printing speeds because the amount of light allows the resin to quickly harden. DLP is a robust technology that produces high-resolution models every time, even allowing you to use cheaper materials for complex and detailed objects.

Fused Deposition Modeling (FDM) is filament 3D printing, the most popular and readily available form of 3D printing available on the market. Developed and originally implemented in the 1980s, FDM allows you to print operational prototypes as well as ready-to-use products as such LEGO, plastic gears and much more.

All components printed with FDM can go in high performance and engineering-grade thermoplastic, which makes this technology useful for mechanical engineers and manufacturers. Printed pieces have excellent mechanical strength and heat resistance. FDM printers construct 3D objects layer by layer, starting at the bottom and moving upwards by heating and extruding thermoplastic filament. This form of 3D printing is useful in all fields, from new product development to prototyping to end-product manufacturing.

There are several key factors to consider when deciding whether an FDM or SLA/DLP printer is the right choice for you.

• Cost - When purchasing a 3D printer, it is not only the printer cost that you must take into account; it is the filament or resin cost, as well as other accessory and time demands. On printer cost, FDM printers easily win over SLA/DLP printers at every level. Especially for novices, budgetand entry-level SLA/DLP printers are few and far between. In addition, you must consider the upkeep of the printer. A spool of filament will cost you $25 or less, with infrequent nozzle replacement given regular cleaning and maintenance. With resin printers, you will need to replace both resin and resin tanks frequently. A tank costs $40 or so, and a liter of resin is around $80. When comparing costs, an FDM printer is far more affordable. 

• Quality - A major consideration in 3D printing is the quality of objects that you will be printing. FDM printers rely on several factors, such as extruder precision, nozzle size and adhesion between layers. Warping, shrinkage and shifting are not uncommon as the layers are slowly squeezed together. However, these issues can be cleaned up in post-processing. On the other side, SLA/DLP printers provide superb quality because the laser determines fine details, leading to extremely precise, high-quality print jobs. When comparing finished products, resin 3D printing yields better final results.  

• Ease of Use - There is a definite learning curve no matter if you choose a filament or resin 3D printer. For filament printers, you will need to remove the final print from the print bed using a palette knife and then perform some post-processing snipping off of excess plastic, as well as a bit of sanding. For resin printers, removing the final print is a bit more cumbersome as there is a lot of excess resin leftover. In addition, objects will need to be wiped with isopropyl alcohol and sometimes put into an ultraviolet oven for final processing. Both printer types require postprocessing, though filament printers might be a little easier to use. 

Choosing the 3D printer that is right for you depends on your needs and the objects that you are creating. Filament and an FDM printer is the right choice for hobbyists and makers, those building low-cost materials, when strength and durability are important or when precision and surface finish aren’t crucial. Resin and an SLA/DLP printer is the right choice when high precision and smooth finish is of utmost importance and cost isn't a factor.