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

A CAD file is all that’s needed to start producing parts — no tooling is required. The first batch of parts is available in hours, as opposed to weeks.
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).

BMW builds hundreds of custom assembly tools with FDM direct digital manufacturing.
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.

During the vacuum assembly process, a component is placed in a custom pallet produced via direct digital manufacturing. Oreck saved $65,000 on tooling costs for this project.
Whichever technology is chosen, DDM offers unique and powerful advantages that distinguish it from traditional manufacturing methods. The advantages cited most often are:

  • Eliminating investment in tooling.
  • Eliminating lag time between design and production.
  • Eliminating design constraints.
  • Eliminating penalty for redesign.
  • Eliminating 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 manufacturing technologies are fairly “green” processes. They have very little waste material compared with milling processes because only the needed material is used. No unnecessary inventory is produced because there is no benefit to building more than you need at any time. Most additive processes require no harmful chemicals and vent no harmful fumes into the environment. Among other green benefits is the relatively small amount of electricity that is required to produce parts via additive manufacturing.

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.

Application Diversity

A batch of parts produced via direct digital manufacturing is unloaded from the additive manufacturing machine.
In the manufacturing environment, DDM often performs one of two roles. Companies will use the process to manufacture the products it sells, or to make the devices that aid in the manufacturing of the products.

When first introduced to DDM, the application most people envision is the production of finished goods. The word manufacturing conjures images of high-volume production of consumer products. People often jump to the definition “the making of goods on a large scale,” even though manufacturing also means “the making or producing of anything.”

DDM is suited for low-volume manufacturing, not mass production, but before you think, “We can’t use it because we do mass-production,” keep in mind every manufacturer has low-volume needs in the production of manufacturing tools, such as jigs, fixtures, gages, and hand tools.

Producing manufacturing tools presents the ideal opportunity to try DDM. These tools are deployed to make manufacturing and assembly fast, efficient, repeatable, and cost effective. In this manufacturing context, DDM becomes a low-risk, high-return alternative to standard practices. Because the tools are used by the company rather than 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. Performing DDM of manufacturing tools is currently more popular 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.

Manufacturing can also be a bit of a misnomer when the entire spectrum of industries using DDM is considered. Some of the greatest successes are not in the manufacturing industry. Because of the inherent need for custom-fit devices, the medical and dental professions have been early adopters of DDM. Orthotics, prosthetics, hearing aids, and dental bridges have all benefitted from DDM. Companies have discovered that DDM is a powerful alternative, rather than a direct replacement, to the conventional manufacturing processes.

DDM is a fundamental shift in the approach to making parts. It is a process that employs additive manufacturing to make end-use parts directly from CAD data. DDM is a promising manufacturing alternative that accelerates production and reduces costs while creating new possibilities, and permits new business models. It is unique because it avoids molding, machining, and forming, and it eliminates the constraints that these conventional manufacturing methods impose.

Most likely, your company’s product development department has either an in-house additive manufacturing system for rapid prototyping, or they outsource prototypes to a service that uses additive manufacturing. In either case, talk with the design engineers in product development, and ask about a sample project. Ask if they will build you a simple manufacturing tool like a small jig, fixture, or gage. And compare the cost to what you spend having the tool produced via traditional means. If you find a simple entrance into direct digital manufacturing this way, you will join the many leading companies who discovered DDM via the same path.

This article was written by Scott Crump, CEO of Stratasys Inc., Eden Prairie, MN. For more information, Click Here 


NASA Tech Briefs Magazine

This article first appeared in the September, 2010 issue of NASA Tech Briefs Magazine.

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