Posted by Robert Kiser on Mon, Feb 16, 2009 @ 09:47 PM
Laser Scanning is a non-contact technology that digitally captures the shape of physical objects using laser light. A laser probe projects a line of laser light onto a surface while cameras continuously triangulate the changing distance and shape of the laser line as it sweeps along, digitizing the object in three dimensions (see below for more information about laser triangulation).
Laser triangulation is an active stereoscopic measurement technique that computes the distance of an object with a directional light source and a video camera. A laser beam is deflected from a mirror onto a scanning object. The object scatters the light, which is then collected by a video camera located at a known triangulation distance from the laser so that the 3D spatial coordinates of a surface point or line are calculated. The CCD camera’s 2D array captures the surface profile’s image and digitizes all data points along the laser and can be seen here:
Overview of 3D Laser Scanning, Dimensional Inspection & Long Range Scanning
Rapid prototyping steps in when the scanned output data is saved as a stereolithography file solid CAD file. This file can then be created into a physical 3D model for analysis via use of rapid prototype 3D printing technology.
Posted by Robert Kiser on Fri, Feb 06, 2009 @ 11:42 AM
Microtechnology is a term first applied to semi-conductor technology where an array of circuits could be put on a single chip. Microtechnology is technology with features near one micrometer (one millionth of a metre, or 10-6 metre, or 1μm). Inkjet printers are a good example of microtechnology.
The PolyJet 3D printing technology has the highest resolution in the Z-Axis (height measurement) and builds 3 Dimensional rapid prototypes layered together at layer thicknesses of .0006" (.015mm), or 15.24 microns. Comparing the PolyJet 3D printer rapid prototype system to other systems on the market, I consider the PolyJet a microtechnology because it breaks the barrier traditional rapid prototype systems are currently confined in. With a Z-Axis build capability of 15.24 microns, I can consider this close enough to define PolyJet as a rapid prototype "microtechnology". All PolyJet systems also have mechanical tolerance specifications they must be tuned within to meet the definition of the final product. Some of the calibrations require tuning to specification of less than 1 micron.
I just delivered a product to a customer who had literally been struggling to get a quality 3D prototype for a little over a year. This customer was so worn down by the bad quality 3D models he had received, along with all his questions being explained away, he didn't even trust what i was saying. I finally told the customer I would build a sample for free. Once they received the sample, all apprehension about using another rapid prototype service was gone and I was chosen to produce their exciting models. In summary, there was no other technology that was capable of building the project except the PolyJet prototype printer.
3D printing technology is a rapid prototype technology in and of itelf because it is a microtechnology, a true prototype printer, and a microtechnology that is a rapid prototype system using additive manufacturing as it's process.
Posted by Robert Kiser on Sun, Jan 25, 2009 @ 11:55 AM
Yes, and let me explain why.
When most people think of a printer, the image that comes to mind is a device you print a computer generated document to. I asked some very bright associates of mine what came to mind when I asked them what a 3D Printer is. They all stated it was a device that printed blueprints from 2-Dimensional drawings. I told them they were very warm.
All rapid prototyping systems use a concept to place a 2-Dimensional image on top of another. These processes differ in method per system manufacturer, but the end result is the same. This is an additive process to "grow" a shape that takes up more and more space. It is a physical process that requires that each 2-Dimensional image be somehow "fused" together to create the final solid shape. You might then think that this 2-Dimensional image really isn't 2-D after all, because if you could held it in your hand, it would actually be a 3-Dimensional solid mass. The 2-Dimensional images that rapid prototype systems use to create 3D models are in fact a large (or small) series of 2-Dimensional images, like the images you see on a computer screen. The are referred to as "bitmap" images, and their appearance to the naked eye is controlled by what is termed "resolution". The higher the resolution, the easier it is to see the image. There are software programs in existence that can design an image that is 3-Dimensional in appearance on a computer monitor. This 3-Dimensional image is what is called a "Solid Model". This is where the rapid prototyping process begins.
Once the 3-Dimensional image is complete and ready to be created into a hand held object, some neat things occur. The 3-Dimensional image is saved as a Stereolithography file which is a big series of triangular shapes put together to form the image. This file is then imported into the rapid prototype system's application software and maneuvered around for fastest creation time. When ready, the operator starts the process and the 3-Dimensional image file is sliced up into many of those 2-Dimensional bitmap images I mentioned. So now, our software is acting like a printer at this point. How do we take these images and "fuse" them together into a 3-Dimensional physical objet we can hold in our hand? This is where the rapid prototype system comes in.
The PolyJet is a true 3-Dimensional printer. Think of the PolyJet rapid prototype technology as an overgrown inkjet printer. It holds a liquid inside the jetting heads and jets out each individual 2-D bitmap image, on on top of another. Each 2-D bitmap image is jetted out at a certain mechanical thickness, fused together via ultraviolet light, then machined down to a certain height. This is the point at which a 2-Dimensional bitmap image becomes a 3-Dimensional physical objet.
So, are 3D printers and 3D printing technology rapid prototype systems? Yes, indeed, and the classification is called the "PolyJet" technology and is part of the rapid prototype technologies that exist today.
Posted by Robert Kiser on Tue, Jan 20, 2009 @ 10:35 AM
PolyJet 3D printing technology has two build styles, "Matte" and "Full Glossy". Unlike other rapid prototyping technologies, the PolyJet 3D model printed on the aluminum build tray must be supported as it is grown by a gel-like support material. If the main model walls were not supported, the walls would begin to collapse, the part could separate from the build tray, and damage could occur to the system. The soluable gel-like support structure is easily removed via a water jet spray system. Once removed, the support leaves behind a clean model wall that has a slight Matte finish to the part if the 3D model was printed using the Matte feature.
Some PolyJet 3D models can be created using the "Full Glossy" feature of the Objet Studio software. Full Glossy is a mode feature where no gel-like support encompasses the part. The only support material needing to be removed is the very bottom of the 3D model where a pad of support is used to anchor the model to the tray. Full Glossy mode is reserved for parts generally .787" (20mm) or less in height because collapse of model walls can occur above this height, quality will suffer, and damage can occur. If a part is "dome shaped", then a taller height model can be produced without wall collapse because the wall is supporting itself and no liquid resin runoff can occur. If you have a model cylinder standing on end and there is (for example) a hole running perpendicular through the cylinder, then the inside of the hole must be supported or the hole would collapse in on itself. In this Full Glossy case, there is support added in the part.
"Full Glossy" 3D models look impressive, but there are limitations and risks involved. Also, dimensional tolerances will differ between a PolyJet 3D model printed in Matte versus Full Glossy. If a "ball" shaped part is produced in Full Glossy mode, then half the ball will be Matte finish because the bottom half of the part requires support during the build process. For guaranteed model accuracy and functionality, "Matte" selection is default for the hard acrylics, TangoPlus FullCure930 rubber elastomer, and the DurusWhite FullCure430 polypropylene like resin.