Over the past 20 years, additive fabrication technology has migrated from use in rapid prototyping to become a full-fledged manufacturing solution, referred to as “direct digital manufacturing” or DDM. While the general concept of additive fabrication 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, DDM is a new thing and difficult to understand.

“Additive fabrication” 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 fabrication 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.” There has been some confusion about direct digital manufacturing in part because of the many terms that are used synonymously with it. For some people it is synonymous with “rapid manufacturing,” “additive manufacturing,” or “layer manufacturing,” while others make subtle distinctions among these terms.

Nomenclature notwithstanding, DDM is the process of using CAD or other data (e.g., 3D scan data) to drive an additive fabrication machine that makes usable parts—from jigs and fixtures to sellable products to replacement parts. DDM eliminates molding, machining, casting and forming. Instead of material removal or shaping, a company’s 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 upfront and back-end operations common to traditional methods means that 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. Using our own company’s FDM additive fabrication process for DDM, Stratasys eliminated about $200,000 in tooling costs for one of our newer machines. We did this by directly manufacturing 32 components rather than having them produced via traditional means. From our customers, we hear similar stories with varying degrees of savings regularly. The savings on one project can outweigh the cost of the machine purchase.

DDM is a process, not a technology. It:
-Eliminates investment in tooling.
-Eliminates lag time between design and production.
-Eliminates design constraints.
-Eliminates penalty for redesign.
-Eliminates lot size minimums.

Collectively, these benefits translate to efficiency, flexibility, responsiveness and affordability. DDM is a manufacturing process that introduces alternatives in product design, manufacturing methodology and business operations. As an added benefit, many additive fabrication technologies are fairly “green” processes. They have very little waste material as compared with milling processes because only the needed material is used. No unnecessary inventory is produced because there is no benefit to building more product than you need at any time. Most additive processes require no harmful chemicals and vent no harmful fumes into the environment. Among a list of other green benefits, is the relatively small amount of electricity that is required to produce parts via additive fabrication.

DDM essentially rewrites the rulebook for making manufacturing decisions. In many instances, it is a polar opposite to conventional production methods. This makes it a disruptive technology and makes it more difficult to appreciate and comprehend.

DDM is suited for low-volume manufacturing—not mass production. But it facilitates mass production by permitting the production of manufacturing tools, such as jigs, fixtures, gages and hand tools. Producing manufacturing tools presents the ideal opportunity to try DDM as it is a low-risk, high-return alternative to standard practices. Because the tools are used by the company, not the customer, and the time and cost to produce them is small, an unsuccessful attempt has little consequence. But when successful, DDM has a major impact on productivity, quality and the cost of producing parts. In fact, DDM for tooling production is currently greater than DDM for end-use parts. That’s partly because it’s such a low-risk opportunity, and partly because every manufacturer has a need for such tools.

However, end products are produced with DDM. Because of the inherent need for custom-fitting devices, the medical and dental professions have been early adopters of DDM. Orthotics, prosthetics, hearing aids and dental bridges have all benefitted from DDM. Other types of companies have discovered that DDM is a powerful alternative, rather than a direct replacement, to the conventional manufacturing processes.