Grow It - Rapid Prototyping & Manufacturing

Fused Deposition Modeling (FDM), developed in the late 1980s, is one of the oldest types of additive technologies. An extrusion head is used to liquefy and deposit material, layer by layer, from the bottom up. One way to visualize it is to think of a hot glue gun, which melts hard pieces of glue. Once the glue is extruded, it solidifies in place. FDM works the same way, except is extrudes a plastic instead of a glue. The head follows a tool-path defined by the CAD file and can deposit layers using a head as thin as .005” with the standard tip being .010”.To give you an idea of this size, a piece of human hair is only .003” – .007” thick!

Ok, we don’t want to bore you too much with the technical details, but to truly understand all the amazing capabilities of this technology we want to give you a little more insight through a project that we recently did for one of our clients.

The outline that the tip lays is called the contour, while the zigzag shape to fill the contours is called the rasters. At its standard build of approximately .020” rasters/contours, FDM creates a very strong part. To create a more customized part, the contours and rasters can be modified. For instance, adding more contours/rasters will create thinner strands, thus adding more material in the same amount of space, increasing the strength of the part.

Furthermore, FDM can print in “sparse mode,” which creates a honeycomb structure within the part rather than printing a solid part. The benefits include lighter weight, less print time, and less material, which in turn saves you money.

You can see the difference between the Normal and Sparse Modes below.

(Click on either picture to enlarge it.)

This particular model was printed in sparse mode:

You can see the support filling up on the inside because it was printed using 0 contours, meaning it just created the outline and the honeycomb structure on the inside.

Furthermore, because of this part’s large size, it was puzzle cut into two parts and assembled back together:

This particular model was used for investment casting, but we’ll talk more about that in a later post.