3D Printing System

1. For each layer, a "plow" moves powder from the feed piston to the print piston where it is spread as a thin surface layer.

2. A print head distributes or "prints" binder solution onto the loose powder layer, thereby, forming the cross-section. Where the binder is deposited, the powder is glued together. The remaining loose powder supports the part as it being printed.

3. When a layer is completed, the feed piston is elevated and the build piston is lowered slightly. A new layer of powder is spread over the previous cross-section. The process is repeated until the build is complete.

4. At the end of the process, the build piston is raised and the remaining loose powder is vacuumed away, revealing the completed part. The left-over powder is recycled and can be used for subsequent printing jobs.

The printer's control software accepts parts defined in STL format (Stereolithography Interface Format) or as VRML files (Virtual Reality Modeling Language).

Most CAD and geometric modeling systems allow to export a part's description in either STL or VRML format. If your modeling system does not support these formats as an export function, we can probably help. Please contact us.

Parts need to be defined as solid models, i.e., the data set must clearly define the geometry that is filled with material and the geometry that is empty (like cavities). In VRML, all surfacs must be defined in a way that fully encloses a volume (to be filled with material). Surfaces with no thickness cannot be processed.

Before printing, we can scale the object to the desired final size according to your specification. If the final size does not fit into the build volume (10"x8"x8"), we can subdivide the part, print the sub-parts individually, and glue the pieces together at the end.

Since a major part of the printing cost is determined by the amount of powder consumed (solidified by the binder), you may consider modifying your computer model by creating cavities or making walls thinner (if applicable). For example, printing a solid cube is very expensive. Creating a cavity inside the cube and, thereby, printing only the walls with a reasonable thickness will reduce the cost significantly. However, there must be a way to get the unused powder out of the final part, either by modeling an opening in the bottom wall or by removing the bottom wall of the cube completely.

To shorten the printing time, we will orient a part for minimum vertical height. This allows for finishing the part with a minimum number of print layers. Each vertical inch requires approximately 40 minutes of print time. "Flat" parts can be printed faster. We can also place smaller parts inside the empty spaces of other parts or nest several parts into a compact arrangement. All parts are then printed together in one building cycle. Care must be taken, however, to make sure that parts can later be separated easily and are not accidentally enclosed by other parts.

The cost for printing a part is a function of the amount of material consumed (total volume of solid geometry), of the print time and labor. We can calculate this data before we print and provide an estimate. If we need to manually prepare your computer model for printing, we will charge for additional staff time. The UM3D Lab can currently accept cash, check or short code for payment. Pricing for non-UofM clients is matched to local industry standards, in accordance with UofM policy.

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The UM3D Lab provides support service for the University of Michigan community, and engages in advanced projects with industry. If you have RP or 3D scanning needs that we cannot meet (for material type, size, turnaround time or other reasons) please see the below list of service companies.