Rapid prototyping has become so well developed over the past few years that it has spawned “rapid manufacturing” for production of a range of items direct from CAD data. While the traditionally limited material properties have been a major hindrance to mainstream acceptance, the range and properties available are growing at an impressive rate.

Rapid prototyping, a group of techniques used to quickly fabricate a scale model of a part or assembly using three-dimensional computer aided design (CAD) data, has enjoyed strong growth over the past few years. In fact, the engineering “tool” is now so well developed that it has spawned “rapid manufacturing” for production of a range of items direct from CAD data.

And it is showing few, if any, signs of slowing. In fact, the current global market for rapid prototyping is valued at around $1 billion, estimates Unimatic Engineers at Manufacturingtalk, and it is still growing: at 10 percent to 40 percent a year, depending on the source of expert estimates.

It is the growing variety of options stimulating the increasing adoption of this engineering tool. To address the broad spectrum of industries, companies and products, vendors continue to introduce more and more technologies, systems and materials. According to Design News, “there are more than 50 machines from which to choose, and there are nearly 100 materials to use in these rapid prototyping devices.”

Rapid prototyping includes many related technologies that are used to create parts or models directly from CAD files. After users export a model designed in CAD software to a rapid prototyping machine, the machine builds an accurate model that users can hold in their hands, notes ConnectPress-Pro/ENGINEER. They can check the dimensions of the prototype. They can play with it to get a sense of functionality. In some cases, they can even test to see if parts work as they should. As such, once a designer has completed a CAD drawing, a prototype can be but a few mouse-clicks away, potentially saving time — a rapid prototype can be created in days or even hours — and costs over traditional prototyping procedures.

There are many advantages to rapid prototyping, such as the ease of forming models of great geometric complexity without the need for elaborate machine set-up or final assembly. In the end, rapid prototyping can reduce the construction of complex objects to a manageable, straightforward and relatively quick process at an often-far-lower cost than using conventional techniques.

One of the key developments, brought to market 12 years ago, was the use of a multiple-jet printer, capable of laying down two or more different materials. Often, one of the materials is soluble and is laid down in the voids of the model to support the primary material where required, and is dissolved away once the 3-D printing stage has been completed. This technique has not only made it possible to print very complex and delicate shapes, it has also opened up rapid prototyping to a wide range of applications.

Leveraging low price and a physically small size, and in addition to inkjet-based systems, 3-D printing is arguably the most popular and fastest-growing form of rapid prototyping. Proven to be a viable tool rather than a poor substitute, these devices are finding their way into companies of all sizes. However, it is worth noting that the dimensional accuracy available with 3-D printing (although in the low microns) can be less than is required for precision items, which still have to be made by techniques such as metal cutting, spark erosion and molding.

Stereolithography and laser sintering are two very common rapid prototyping processes, too. Both processes allow users to export CAD files to rapid prototyping machines and in a short period of time create a physical prototype of the CAD model. Right now, both machines are not only very expensive, they are physically large and require specialized personnel to operate. The advantage, however, is that both processes create fairly accurate and durable recreations of the product being prototyped.

Other processes include fused deposition modeling, which allows users to build prototypes quickly with a computer-controlled valve system, and computer numerical control machining (CNC), which allows users to export a CAD file to a network of milling machines to reduce the cost in time and labor.

Ultimately, the materials used in rapid prototyping are limited, which is a major hindrance to mainstream acceptance, as users and prospective users have stated that material properties are their No. 1 criteria.

Yet the range and properties available are growing and currently include various plastics, waxes, resins, ceramics, metals and papers. In fact, the recent Rapid Prototyping & Manufacturing show, produced by the Society of Manufacturing Engineers (SME), gleaned a lot of talk about direct metal technologies and advanced materials, Design News also notes:

At the show, the new class of high-end systems that produce fully dense, metal parts received a lot of attention. These machines push the technology well beyond form, fit and function while addressing the demand for the abundance of parts not made of plastic. The thought of producing one-off parts in stainless steel or titanium, without any tooling, proved to be a strong desire for many of the aerospace, automotive, medical and consumer products companies in attendance.

Materials advancement was a major trend at the show. The number of material options has swelled across the board (with metals playing a significant part). “From plastics to metals, the breadth of material choice and range or physical properties is breaking down one of the biggest barriers to the adoption of rapid prototyping,” Design News claims.

While rapid prototyping can be the final part in some case, the materials in their current forms are not strong enough or accurate enough. Yet the time of suitable rapid prototyping material is approaching — ahem — rapidly.

For an extensive, detailed account of the developments of each of the rapid prototyping processes, we recommend Pro/E Community’s in-depth feature, “Rapidly Moving Toward the Future: The 2006 Rapid Prototyping Roundup.”

Resources

Looking at the future with rapid prototyping
Unimatic Engineers (via Manufacturingtalk), Aug. 30, 2006

Rapid Prototyping Advances
Design News, Sept. 4, 2006

Rapidly Moving Toward the Future: The 2006 Rapid Prototyping Roundup
by John Myers
ConnectPress-Pro/E Community), Aug. 23, 2006