Comparison of 3D Printers

Overview

While there are many advanced 3D printing technologies, it is the low-cost ones that are of primary interest to OSE. The end goal of 3D printing technology is low-end 3D printers able to fabricate more advanced designs semi-autonomously. Achieving this Digital Fabrication objective has fairly wide-reaching economic implications.

=Research

Techniques

[From Mind Tribe http://mindtribe.com/2011/01/3d-printing-rapid-prototyping-comparison/]

3D Printing/ Rapid Prototyping Comparison JANUARY 14TH, 2011 by CHET 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 bumper, Chair, Model 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://mindtribe.com/2009/06/been-there-prototyped-that-what-process-and-when/

This entry was posted in MindTribe Tech and tagged 3D printing, FDM, rapid prototyping, SLA. Bo