With all the new 3D printing machines on the market, it can be confusing to figure out the different types of technologies they employ and their relative advantages. This blog post specifically compares FDM, Projet/Polyjet/Eden, ZCorp, and SLA.
The technologies compared here are similar in some ways in how they produce the final 3D object. The desired 3D computer model is sliced up into many layers spanning the horizontal plane. Each of the machines mentioned here then ‘prints’ each layer starting from the bottommost layer, cures or hardens that layer, then the respective platform in the machines holding the object lowers, allowing each of the machines to ‘print’ the next layer. This process is continued until each of the machines are finished with the topmost layer.
The tables below highlight the key differences and give a rough reference of achievable resolution of ‘pixels’. More detailed information follows the tables.
|FDM – Fused Deposition Modeling|
|Companies||Stratasys (Dimension Printing, Fortus)|
|Technology||A ‘hot glue gun’ dispensing ABS layer by layer|
|Great for||High strength and durability. Won’t shrink/warp or absorb moisture.|
|Limitations||Slow speed, rough resolution|
|Resolution (mm)||Z: 0.178, XY: 0.089|
|Build Material||Spools of ABS or PC|
|Support Material||Soluble resin|
|Post Processing||Support material to be removed by hand and ultrasonic bath|
|Videos||Detail Overview, Fish|
|Companies||Objet (Eden, Polyjet), 3D Systems (Projet)|
|Technology||UV cured photopolymer resin built up layer by layer|
|Great for||High resolution, wide selection of materials (color, clear, rubber)|
|Resolution (mm)||Z: 0.016 , Y: 0.085, X:0.042|
|Build Material||Photopolymer resin (liquid)|
|Support Material||Wax-like resin|
|Post Processing||Support material can be removed by hand but needs to be washed off thoroughly by water jet. Can be soaked in NaOH solution for extra cleaning.|
|Companies||Z Corp (ZPrinter)|
|Technology||Using ‘super glue with color’ to bind fine powder layer by layer|
|Great for||Colorful models. Multicolor surfaces created during printing (i.e. no need for manual painting). Rubber available.|
|Resolution (mm)||Z: 0.089, X: 0.042, Y: 0.047|
|Build Material||Fine powder with ‘super glue’|
|Support Material||Fine powder|
|Post Processing||Blow/brush dust off model, then optional infiltration with strengthening resin|
|Videos||Bearing, Human Head, Robot|
|Technology||A vat of resin cured by laser layer by layer|
|Great for||High resolution and stiff parts|
|Resolution (mm)||Z: 0.025, XY: 0.032|
|Build Material||Photopolymer resin|
|Support Material||Photopolymer resin|
|Post Processing||Support material removed by hand and ultrasonic bath|
|Videos||Car bumper, Chair, Model|
How it works: FDM is an additive prototyping process in which parts are built layer by layer from the ground up. The simplest analogy is that of a hot glue gun mounted on a motorized XY printer table. This glue gun deposits molten glue on the movable platform where a solid part is desired. The molten glue cools and solidifies. The platform then moves downward (Z-direction) to allow the glue gun to print the next layer on the now solid lower layer. In FDM, the glue stick is a long fine thread (~1.8mm diameter) of ABS or PC plastic. The printing process actually uses molten ABS or PC. The glue gun nozzle is the print head. The platform starts at the highest point closest to the glue gun, then steps down 0.178mm at a time to allow the glue gun to print the next layer.
How it’s used: FDM models are used often when strength and durability of the part are critical. The parts are made of actual ABS or PC material, thus shrinkage, warping, or moisture absorption will not be issues. One thing to note is that the weakest bond in the material is in the Z-direction layers since the bond is made by molten material on an already solidified layer. Thus in the unlikely event that the part breaks, it will most likely be along the Z-direction layers. The resolution of the part is not as good as other technologies, thus this is not the ideal candidate for cosmetic models.
How it works: ZCorp Zprinter works by printing binders (think superglue) onto a layer of powder (think fine sand) where the part is to be solid. Once a layer is finished, the platform lowers and another layer of loose powder is added on top of the finished layer. The print head again deposits binders where the part is to be solid. Once the printing is complete, the excess powder is removed by a brush and air gun. The part can then be infiltrated with a low-viscosity resin that helps strengthen the part. One of the big advantages of the ZCorp system is that it is able to add color pigments to the binders, thus allowing for multicolor parts to be made. Other technologies would require manual painting of the parts if different colors are desired on a single part.
How it’s used: ZCorp printed models are great for presentation and cosmetic models since they come full-color out of the machine. It has been widely used for architectural models as well as mockups of product for sales models. I was fooled by a full-color ZCorp printing of a multimeter the first time I saw it since it was so close to the real thing. However, ZCorp models are not great for making functional models where strength and stability are important.
SLA and Polyjet/Projet/Eden technologies (along with machining and SLS) are described in more detail here: