Over the past 20 years, additive manufacturing technology has migrated from use in rapid prototyping to a full-fledged manufacturing solution, which is referred to as “direct digital manufacturing” (or rapid manufacturing). Increasingly, companies are applying it to manufacturing applications, and with each success, they prove that it is a viable alternative. While the general concept of additive manufacturing is the same as when it was introduced 20 years ago, the change is in its intended use — production, not just prototyping. So while the concept has been around for a while, in the minds of many, direct digital manufacturing (DDM) is a new and difficult concept to understand.
Additive manufacturing is the generic name given to processes that create a part by building it up in layers, as opposed to milling or machining, which are subtractive processes. Additive manufacturing was developed as a way to automate the creation of prototypes, and it was therefore originally known as rapid prototyping. It also goes by various other names, including 3D printing, which is one of the most popular.
Direct digital manufacturing is the process of using CAD or other data to drive an additive manufacturing machine that makes usable parts. Examples are the components that go into sellable products, pieces of production machinery, replacement parts, or manufacturing tools such as jigs and fixtures. Besides CAD data, which is the most common type of data used, other types of data may be used to drive additive manufacturing machines. Among others are 3D scan data (for reverse engineering) and DICOM data (for making a physical representation of 3D medical imagery).
DDM eliminates molding, machining, casting, and forming. Instead of material removal or shaping, finished goods are produced by adding material, one layer at a time. Other than a few minutes of pre-processing to prepare a production run and some light post-processing to clean up a part, DDM progresses directly from CAD data to final part. Eliminating the up-front and back-end operations common to traditional methods means there is no extraneous time, cost, or labor. Due to the elimination of tooling, DDM can save tens or hundreds of thousands of dollars on a single project. The savings on one project can outweigh the cost of the machine purchase.
One Process, Many Technologies
DDM is a process, not a technology. It can be performed with various additive manufacturing technologies with diverse capabilities. The additive manufacturing technologies that perform DDM share the fundamental technique of producing parts directly from a CAD data file. They do so by adding material layer-by-layer. However, the many processes vary greatly, so in order to determine if DDM is suitable for a project, it must be evaluated with respect to a specific technology.