Page 49 - Spring2022

FEATURED ARTICLE
Additive Manufacturing Enables New Ideas in Acoustics
Christina J. Naify, Kathryn H. Matlack, and Michael R. Haberman
Introduction
Additive manufacturing (AM), also known as three- dimensional (3D) printing, refers to the process of building a solid object in a layer-by-layer manner to create a desired object. This fabrication approach opens a multitude of new possibilities across virtually all areas of acoustics, ranging from advances in musical instruments, new acoustic mate- rials, and acoustic metamaterials to new opportunities for ultrasonic nondestructive evaluation to new transducer geometries and concepts and customized hearing aids.
AM fabrication is a generic term and can be achieved using a range of techniques. Most AM fabrication techniques create, or “print,” objects in a process that begins by first placing a small amount of material in a thin layer on a platform. More material is then placed on the first layer at locations that are defined by the geometry or shape of the object being built and then joined, or “added,” to the existing layer. The process is repeated in a layer-by-layer fashion until the entire object is created. In general, the key feature of AM is that material is added where it is wanted by adhering material to previously deposited layers. Over- views of some of the most common AM approaches are included in this article, but the approaches outlined here are only a small slice of a very rich technological field.
The “additive” in AM is in contrast to more traditional sub- tractive manufacturing in which one begins with a solid block and material is removed where desired to create the final object. Although the approach of AM has been around since the 1980s in academic and industrial laboratories (Ngo, 2018), the past decade has seen an explosion in the availabil- ity of 3D printers (the device used to fabricate objects using AM technology) as well as in the price reduction for pur- chasing printers and supplies. These two factors mean that this exciting technology is available to virtually all individu- als or institutions that would like to explore the possibilities
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afforded by AM. Indeed, it’s not uncommon to start a con- versation with someone about AM, only to find out that they have a 3D printer in their home office or garage.
The appeal of AM to a wide audience is easy to see once you know about the possibilities it provides. Users are often attracted by the versatility of AM. Because parts are built layer by layer, the final objects can take almost any shape that the builder can imagine. This means that a user can often use a single 3D printer to iterate on designs or print a wide range of objects without having to create custom molds or tooling often required in conventional fabrication methods. Figure 1 shows a cartoon example of a single 3D printer being used to print a flute (Ritz, 2015), an ear pinna (Prepelit,ă, 2020), and an acoustic speaker housing
Figure 1. Additive manufacturing (AM) offers manufacturing versatility. Traditional methods would require different approaches to build items such as musical instruments (left); hearing prosthetics (center); or speakers (right), but AM technology has the potential to build each of these on the same desktop-style 3-dimensional (3D) printer without special molds or custom tooling. In fused deposition modeling (FDM), this is achieved using a material print head, or extruder, that is moved in horizontal and vertical directions (arrows) while molten material is deposited in the desired location.
Volume 18, issue 1 | Spring 2022 • Acoustics Today 49