Manufacturing

The RP&M Report and RepRap

6 Jun, 2007 By: Jeffrey Rowe

It may sound like science fiction, but the self-replicating machine is evolving as you read this.


A couple of weeks ago I attended the RAPID 2007 conference sponsored by SME (Society of Manufacturing Engineers). As usual, I came away with several noteworthy items in the world of RP&M (rapid prototyping and manufacturing), including Wohlers Report 2007 and an update on the RepRap Project, both of which I consider important to the future of manufacturing technologies and their implications.

Over the course of a year I get asked to review a lot of engineering and technical books. I decline many because they're either too academic and theory-oriented or they cover topics that are marginal to mechanical design and engineering. However, several books are published that are informative and insightful. The past few years, I've come to know what is considered by many to be the bible of RP&M -- Wohlers Report 2007: State of the Industry, Annual Worldwide Progress Report. I know the author, Terry Wohlers, and can attest that he knows his stuff.

The report, published annually for the past 12 years in its current format, has expanded dramatically since its first edition, is well over 200 pages this time around and, as always, has been extensively updated to reflect the latest information available for the RP&M industry. Wohlers uses the term additive fabrication to describe rapid prototyping throughout the book. Today's application of the technology spans beyond prototyping, so he argues that it can be inaccurate and misleading to use rapid prototyping when referring to the technology. Prototyping is only one of the technology's applications. The report covers concept modeling, prototyping, the production of patterns for metal castings, tooling, and custom and short-run production.

From a global perspective, Wohlers Report 2007 addresses many topics relating to additive fabrication, including its history, its various applications, the industries embracing the technology, annual revenues from products and services, growth estimates and sales forecasts and investor information. The final parts of the report cover emerging technologies and concludes with a discussion of the future -- where it is headed and what to expect -- to assist in strategic planning and investment decisions.

If you are involved with the additive fabrication industry or are just thinking about getting into it, at whatever level for whatever reason, I highly recommend Wohlers Report 2007 as the source of information for RP&M.

The Dream of the Self-Replicating Machine
Some of the more interesting formal and informal topics of conversation at RAPID 2007 were the several current events and projects for improving rapid prototyping technology to the stage at which a prototyping machine could manufacture a majority of its own component parts. Of these, the RepRap Project is generally acknowledged as one of the more advanced. The idea behind this and similar projects is that a new machine can be almost entirely manufactured and assembled inexpensively from the same material that the rapid prototyping machine uses to make prototypes. Self-replication techniques such as this could considerably reduce the cost of prototyping machines in the future, not to mention as the objects they are capable of additively fabricating.

The RepRap (short for Replicating Rapid-prototyper) project is working toward creating hardware and software as a universal constructor system by using rapid prototyping, and then, on an open-source basis, giving the results away free under the GNU General Public License to allow other investigators to work on the same idea and improve it.

The project uses FDM (fused deposition modeling), and the RepRap machine is a three-axis positioning system with a thermoplastic extruder, analogous to an automated glue gun. It is made of plastic parts and makes plastic parts, so it can literally make copies of itself. It has a build cost of less than $500, and the full plans and documentation are available for others to use and improve upon. Currently, commercial 3D printers produce parts costing one to two dollars per cubic centimeter to fabricate. The RepRap Project is on track to produce objects at a cost of about two cents per cubic centimeter -- a huge difference.

RepRap has been conceived as a complete replication system rather than simply a piece of hardware. To this end the system includes CAD and CAM software and drivers that convert RepRap digital designs into physical objects.

The RepRap system uses the open source Aol (Art of Illusion) 3D modeling system as its front end. AoI is well suited for this purpose both because of its ability to model 3D objects and because it is written in the ubiquitous multiplatform Java programming language. The core AoI modeling platform is tailored to the needs of the RepRap project via scripts, and RepRap's CAM system has also been written in Java.

Adrian Bowyer, a senior lecturer in mechanical engineering at the University of Bath, United Kingdom, invented and initiated RepRap. While the RepRap project was formally launched in March 2005, the hardware's development really took off after Bowyer developed the fused deposition extruder in November of that year. The machine represents a major advance in the state of the art because it can operate at room temperature rather than a closed box heated to a temperature just below the melting point of the polymer material being extruded. This fact alone greatly reduces the cost of producing a system and makes specifying materials used in such systems less critical.

Last September the RepRap prototype successfully printed the first part of itself, which was subsequently used to replace an identical part originally created by a commercial 3D printer.

The goal of the RepRap project is not so much an endeavor to produce just a self-replicating device for it own sake, as much as it is an effort to put in the hands of others, for a minimal financial outlay, a desktop manufacturing system that can produce physical objects.

This year has been a good one so far for many aspects of RP&M. It seems to be catching on in wider circles and having greater influence on future manufacturing technologies and practices, as evidenced in Wohlers Report 2007 and RepRap.


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Lynn Allen

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