Additive Manufacturing (3D Printing): What is it and how is it used?

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Traditional manufacturing and machining processes typically begin with a simple block of material and functional parts are created by the removal (subtraction) or shaping the material from the initial volume.   In contrast, additive manufacturing is a process in which parts are created by the buildup (not removal) of material into a desired shape or form.

As early as the 1980s, companies have been developing equipment to produce components through a buildup of materials.  Stereolithography is the forerunner to today’s 3D printing technology, but the process required specialized materials that could be selectively cured with use of focused UV light.   These UV cured parts were fragile and ultimately of limited utility.  However today, 3D printing is enjoying an explosion in both popularity and utility.  The recent trend in the field is due to availability of economical 3D printers and an expanding array of material choices, including a variety common plastics and even metals.

A common method of 3D printing of plastics is through the technique known as Fused Deposition Modeling (FDM).  An FDM part is created by extruding heated, molten plastic into a fine ribbon which is laid onto a smooth flat platform.  The FDM part is created by tracing out and filling in material in the shape of the part, in a layer by layer process.   Figure 1 shows an example part created by this technique and the zoomed view shows the layer by layer stacking of the individual ribbons of plastic.

#D Printed Part

Figure 1: Example of a 3D printed component, illustrating the ability to reproduce complex geometries and fine printing resolution.

3D printing has found utility in a wide variety of applications.  A printed part can be used simply to check basic dimensionality or it can used as a fully functional component in a commercial product.  The ability to build up a part offers certain significant advantages over a traditionally machined component.  The 3D printing process can be used to create internal features in a part not otherwise machinable or the creation of a geometry with internally varying densities.  For example, in a part that has regions of low stress, the internal density of the part can be significantly reduced.  The reduction of density both lowers the weight of the part and the amount of material used during the parts creation.  In other words, a 3D printed part can be created to use only the amount of material it needs.

Metal parts created through a process known as laser sintering can have material strengths that approach that of their raw materials.  However, when creating components in plastic using the FDM process, special precautions need to be considered.  Perpendicular to the layers, plastic material parts can exhibit a high level of strength relative to the raw material properties, but in the layered direction the part strength is halved.  What this means is that designer need to consider the parts that they design may not be homogeneous in strength and need to control the orientation of the printed part relative to its intended use.

The last decade has yielded exciting advancements in the area of additive manufacturing.  Use of this technology is wide spread and is now available to anyone, from a garage level inventor, to a product designer in major corporation.  Over the next decade, the impact of ready access to 3D printing technology will be seen throughout many product sectors and industries.