By MICHAEL ARMBRUSTER, HDRP
3D Printing has been a fascinating reality for some time now. Recently, thanks to an article in The Economist, presentations on TED, and a great deal of interest on Wall Street, the industry is now garnering interest from wide-ranging audiences. Unfortunately, however, the various capacities and options that underlie modern 3D printing remain a mystery to those who could benefit from them the most. How about these terms: SLA, FDM, SLS, DMLS, and HD Printing – do they resonate with you? If not, here are some brief explanations.
SLA (Steriolithography) is where it all started. For some time, SLA was to 3D Printing what Kleenex is to facial tissues. It didn’t matter what process you were using, people called it SLA. Yet it is just one of many processes, and it starts with a large vat of resin. A laser runs across the surface of the resin, curing one layer at a time, transforming it from liquid to solid. This continues, layer after layer, until you’re left with a solid part. The layers are generally .003”-.005” which allows for a nice representation of the original CAD data. SLA tends to be a good middle-of-the-road process when it comes to the three things most people are concerned about: price, resolution, and material properties.
FDM (Fused Deposition Modeling) is today probably the most well-known 3D Printing technology. It essentially works like a sophisticated hot glue gun. A wire of material, often ABS, is pushed through the machine, melted, and extruded through a small nozzle which moves along the tray tracing each layer of the part. There are two great things about FDM, the price and the material. FDM machines are generally inexpensive compared to other technologies, and the machine often uses a true ABS plastic, making parts that can safely be used in many end-use applications. The relative disadvantages to FDM are the resolution (.01” layers) and the slow speed at which the machines run.
SLS (Selective Laser Sintering) is an amazing technology if you’ve got the money for it. SLS starts with a large bath filled with powder. As the name implies, a laser then sinters the powder, one layer at a time, to print your part. The materials are fantastic and include a variety of different composites, such as glass-filled nylons and carbon fiber. The resolution is very nice – often finer than SLA, though layer numbers vary based on the system at hand. The only noteworthy disadvantages to SLS, in my opinion, are the sandy surface finish of the parts and the massive price tag. These machines are expensive both to buy and to run.
DMLS (Direct Metal Laser Sintering): For this technology, take everything I said about SLS but add more emphasis on the amazing variety of materials available (metals such as stainless steel and cobalt chrome),and then proceed to add more emphasis on the expense.
HD Printing may be an unfamiliar term to you because, well, I made it up. 3D Printing originally entailed additive machines that utilized a print head. However, the name 3D Printing became mainstream, and now all the above processes are referred to as 3D Printing even though none of these actually use a printhead. Consequently, we don’t really know what to call the machines that used to be called 3D Printers, so I’m making up my own slang here and coining the term HD Printing, or High Definition Printing. These are the machines made by companies like Objet, and they more-or-less blow the other technologies out of the water with regard to resolution and surface finish. Printing at 600 DPI with layers as thin as 16 microns (.0006”), these machines are perfect for your small to medium sized consumer products. The material properties might not blow you away, but they’ll hold extremely tight tolerances and make for very nice show pieces. Also notable is their speed. The printhead swipes across the entire tray at once. So while one part might take three hours, ten parts might only take three hours and fifteen minutes if they can all fit onto the tray. I should tell you that if I sound biased toward this technology, I probably am, because it’s how I make my living at www.HDrapidprototypes.com.
I’ll conclude this article by stressing that the opinions I’ve expressed here are my own, and they utilize a slew of generalizations. Please understand that this article is in no way a thorough or complete representation of this fascinating and ever changing industry.
For more information, please visit www.HDrapidprototypes.com.