Question : Why PolyJet 3D Printing?
Answer : PolyJet resins provide nearly all the strength in functionality most users need. The PolyJet is a 3D printer and not a laser based system that has thermal energy remaining on the outside of the build plane sweep, or an extruder that pushes molten plastic under pressure out of nozzles where excess plastic overruns the edge of the build plane sweep. Hence, PolyJet parts have much smoother wall surfaces. Surface resolution, high quality, and accuracy of the rapid prototype parts have given customers an easy decision to make 3D Printer technology the “go to” technology for physical rapid prototype part creation. These reasons are why Kaiser3D chose the PolyJet 3D Printer as its first line system.
Question: Can functional threads be created in a PolyJet part?
Answer: Yes. If your CAD design has both thread & screw built into it, expand the female portion in CAD .005" for very small features and .010" for large features. If the male screw (insert) is also going to be a rapid prototype, then the threads need to be shrunk .005" or .010". If you are going to use an "off the shelf" metal, plastic, or other material type insert, then the female portion in the rapid prototype design must be the same size as the "off the shelf" insert.
Question: Will part dimensions measure a specific number (Example: .005”) tolerance across all measurements in the part?
Answer: Rapid prototype system manufacturers normally state one specific tolerance the part measurements should never exceed. From experience, a critical dimension on a part may measure +/- .002” off dimension on one side of part, while on the other side, a dimension may measure .003”, .001”, or .000” etc. The reason for this is what is termed "repeatability". The mechanics and software programs of automated manufacturing equipment affect repeatability of critical subsystems within whole systems. Some manufacturing systems have better critical dimensional accuracy capabilities than others. For example, I'll use a laser traveling across a build area of one foot in the X plane (left to right, or right to left). That laser energy beam looks nice and smooth as seen by the human eye as it draws a bitmap image of a certain depth (layer height in the Z axis) into the medium. What we can't see is that the laser is not actually traveling smoothly. It stops and starts (shutters) a little in it's travel and deviates off a straight line a little here and there. Hence, what is expected of the laser isn't totally "repeatable". At one point in X, say at the 2" mark of travel, a measurement on a part may measure .003" off expected dimension. At another point, say at 6", the expectation may be better and a dimension may measure +/- .001" off the expected dimension. There are deviations in all axes on all manufacturing systems, some systems with better repeatability than others and the system may be the same model and manufacturer. For this reason, it is CRITICAL to have good and knowledgeable Field Support Engineers supporting your systems. In the Field, I have never seen a PolyJet part measure more than .005” off actual dimensions in all axes and normally measures no more than .001" to .0025". A maximum dimensional tolerance number is issued by manufacturers as a baseline tool for Field Engineering and Applications of what to expect and should not be considered what you will get in reality. State of the art software applications have increased repeatability excellently over the last 10 years in Rapid Prototyping and other manufacturing systems. In reality, a manufacturer states a maximum tolerance value average that is normally very high and all systems can be tuned to degrees of calibration for tolerance values of normally +/- .005" and less. Again, it is a baseline number. But in general, the PolyJet 3D Printer system produces impressive dimensional accuracy.
Question: The surface resolution and quality is intense on PolyJet 3D printer parts and I sometimes see triangle facets or gaps on the surfaces of parts I've received from other vendors. What is this?
Answer: The triangle facets or gaps you see on the surface of your rapid prototype 3D model are actual problems within the Computer Aided Design (CAD) solid model file. The PolyJet 3D printer produces such intense resolution parts, any major problem with a stereolithography file can be displayed in the actual part. A flaw in a CAD file may be minor, at other times, major. Kaiser3D checks every incoming file for integrity and errors by way of a specialized software that scans the entire makeup of the stereolithography part and in most cases can automatically repair the file at no additional cost to the customer. This process minimizes or eliminates any issues within the stereolithography file & minimizes or eliminates extra time a Designer must spend fixing the file. Good stereolithography files are critical for most rapid prototype systems because if a part comes apart during machine operation, damage can and has occurred to expensive subsystems of the machinery.