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
Polyjet/Eden/Projet
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)
Limitations High cost
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.
Videos Detail Overview
Z Corp
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.
Limitations Low strength
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
SLA- Stereolithography
Companies 3D Systems
Technology A vat of resin cured by laser layer by layer
Great for High resolution and stiff parts
Limitations Slow speed
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 bumperChairModel

FDM

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.

Simplified view.

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.

ZCorp

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.

Simplified view.

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:
http://www.mindtribe.com/2009/06/been-there-prototyped-that-what-process-and-when/

Posted by & filed under MindTribe Tech.

One Response to “3D Printing/ Rapid Prototyping Comparison”

  1. Jason

    There is a company that was featured on hackaday called growit3d: http://hackaday.com/2010/05/09/multiple-material-3d-printing/

    After using the more traditional method, I thought I would give these guys a shot. I spoke to the guy in the video, one of the nicest guys. They made me a handful of units which ended up being much cheaper. But at the end of the day, you get what you pay for. They didn’t feel as nice and the accuracy isn’t as good. However, if you aren’t looking for 5 mil accuracy, these guys are definitely worth the bang for your buck.

    Reply

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