The Arrival of RP and its Value to US Manufacturing

Terry Wohlers

Published in the Proceedings of the Rapid Prototyping for Product Development, Design,
and Tooling Conference, held October 24-25, 1995, at Georgia Tech
Copyright 1995 by Wohlers Associates


The pursuit continues to find faster ways of manufacturing quality products. No longer can companies spend years designing, prototyping, testing and tooling for a product that may have a life of only a couple of years. Rapid prototyping (RP) is a technology that is dramatically impacting the way products are designed and manufactured. RP may well be the most important invention since CAD solid modeling. The two technologies are complimentary, and when you put them together, manufacturing companies gain a strong competitive edge. Significant market growth, coupled with a wide range of R&D projects now underway, are evidence that US industry, academia and government are embracing the technology.

If you design and manufacture mechanical parts and assemblies, it's probably safe to assume that you've heard about or experienced the benefits of rapid prototyping. For companies around the world, RP has reduced the time it takes to design and manufacture products. RP has also helped to save these companies serious dollars, Deutsche Marks and yen.

RP machine sales and services began to expand significantly last year and it continues to grow. The reasons are many. First and foremost, manufacturing companies are becoming familiar with what the technology has to offer, an educational process that has taken years. Second, the range of RP processes that are commercially available have improved. Today, it's possible to produce relatively accurate parts in materials such as epoxy resins, ABS plastic, and glass-filled nylon. The list of possibilities continues to grow.

Third, companies are finding that they can justify the cost of RP on the basis of improving the quality of a design and avoiding expensive mistakes. Receiving a physical model of a proposed design early in the design cycle permits them to make improvements when changes are inexpensive. RP helps them to catch design errors long before production tooling. Oversights at this phase can cost tens, even hundreds of thousands of dollars. Also, it can delay product introduction, giving the competition a time advantage. A decade ago, you could get away with delays of weeks or months, but this is no longer acceptable, especially with products that have a life of only a year or two.

CAD solid modeling

Advances in CAD solid modeling have contributed to the growth of RP. Without a CAD model, it's impossible to produce an RP part, with the exception of data from CT scanners and 3D digitizing systems, although they represent a small percentage of the data driving RP machines. So when referring to RP as an aid for mechanical design, almost all parts are built from a CAD model, and nearly all of the them are solid models. For this reason, the RP market will only grow as fast as the solid modeling market.

RP and CAD solid modeling are complimentary technologies, so they help to justify one another. I know of companies that purchased solid modeling systems, but not until they made the decision to go with RP. Also, companies are buying solid modeling systems because it secures them a future path to rapid prototyping. So they really do help sell one another. Some companies view the solid model as the soft prototype and the RP part as the hard prototype.

RP requirements

RP requires that you produce a fully closed, water-tight model. If you were to pour water into the walls of the part, it should not leak. For this reason, CAD solid modeling has become the most popular method for preparing model data for RP. Surface modelers enable you to meet this requirement, but most users will agree that using a solid modeler is far easier. Without even trying, a good solid modeler will automatically produce water-tight models.

The link between the CAD model and the RP machine is the STL file. An STL file is nothing more than a list of x, y and z coordinate triplets that describe a connected set of triangular facets. Also, it includes the direction of the normal vector for each triangle, which should point outward. CAD systems with an STL translator perform a surface tessellation and then output the facet information to either a binary or ASCII STL file. Binary STL files are much smaller and usually preferred, but ASCII STL files permit you view the contents of the file and even edit it if necessary.

Certain RP systems, such as machines from 3D Systems and Stratasys, require support structures which support the RP part as it is being built. While it is possible to produce custom support structures with your CAD software, don't. Most owners of RP systems use support generation software that automatically creates supports structures for an STL file. It is many times faster and it does a better job.

RP's growth

The RP industry is experiencing unprecedented growth in revenues and unit sales. Revenue estimates from product sales and services grew by nearly 100% in '94, making RP an estimated $198 million industry. If you add in the secondary tooling and duplicate parts that come as a result of RP, the industry mushrooms to an estimated $280 million, conservatively.

Unit sales grew by a portentous 84%, from 183 units sold in '93 to 336 sold in '94. In the first quarter of '95, the installed base of RP systems surpassed the 1,000 unit milestone.

Product sales

For most U.S. vendors, sales are on the rise. 3D Systems led the pack in 1994 with 94 systems sold, followed by Helisys which sold 76 systems. 3D's accumulated unit installations remains ahead of Helisys by a margin of more than 4 to 1. In the first 6 months of this year, 3D Systems has already sold 65 SLA systems.

Sales from Japanese system manufacturers have been slow. At the end of '94, the installed base of RP units in Japan represented an estimated 14% of the worldwide base of installations. However, Denken Engineering and Kira Corp. are beginning to move systems. These companies sell systems priced at about $75,000 and $140,000, respectively, which is much lower than the average cost ($530,000) of other Japanese RP systems.

System sales from European vendors are growing, with EOS leading the pack. EOS almost doubled their system sales in '94 (16 units) compared to the previous year (9 units). The company has reported sales of 18 stereolithography and selective laser sintering machines for the first 6 months of this year.

Globally, revenue from product sales grew by an estimated 59%, which is 23 percentage points higher than what Wohlers Associates conservatively predicted for '94. In '93, system manufacturers sold an estimated $49.3 million worth of RP products (materials included). In '94, product sales added up to an estimated $78.6 million. Product sales for the last three years ('92-'94) has grown, on average, 35% per year.

3D Systems' installed base represents half of all systems installed. The remaining 15 system manufacturers share the other half. With an installed base approaching 500 systems, a major portion of 3D's revenue now comes from non-system sales such as resins, maintenance agreements and services from their technical centers. Maintenance agreements and services add up to about $14.5 million, which accounts for one-third of the company's '94 revenues.

Service business

The list of service bureaus (SBs) has grown from 105 to 155 in one year, according to CAD/CAM Publishing, Inc. (San Diego, CA) which publishes the Rapid Prototyping Report. That's an increase of 47.6 percent. Denton & Company (Bloomfield, MI) reports that more than 250 companies worldwide are now in the service bureau business. Established SBs have expanded their operations by adding more machines and people as the demand for RP parts and related services have increased. All of this adds up to a business of considerable size.

Laserform, Inc. (Auburn Hills, MI) once again teamed with Wohlers Associates to determine the approximate size of the RP service business. Conservatively, we found that the worldwide RP part-making business has grown to an estimated $95 million in 1994. This figure does not take into account the secondary tooling and duplicate parts that result from RP patterns. Add in an estimated $83 million for this segment of the business. At this time last year, Laserform and Wohlers Associates estimated the '93 SB business to be in the $40-60 million range (excluding secondary tooling and duplicate parts), another conservative assessment.

Other revenues in the RP industry come from maintenance contracts and service agreements, educational programs, training and consulting services. In 1994, revenues from these sources added up to an about $24.8 million. Wohlers Associates did not break out this segment of the market prior to '94.

Summary/Future growth of RP

RP is growing at an impressive rate. The technology is helping companies justify the cost of implementing CAD solid modeling. Producing physical models and prototype parts from a CAD model has never been so easy. As the CAD solid modeling market grows, so does the RP market.

Based on recent growth trends, Wohlers Associates forecasts the '95 market to exceed $318 million, up from 1994's $198 million. Furthermore, Wohlers Associates expects the market to reach $475 million in 1996. These forecasts include the sales of RP products and services, but they do not include revenues generated from secondary tooling and duplicate parts. Unit sales should hit the 1,500 mark by the end of '95, with as many as 540 units sold this year.

Industry consultant Terry Wohlers councils organizations on how to select, manage, and develop technologies for CAD/CAM/CAE, rapid prototyping, and reverse engineering. You can reach him at (970) 225-0086, fax (970) 225-2027, e-mail

Appendix A: STL viewers and editors

Now that RP is increasing in popularity, users of CAD solid modeling are producing a growing number of STL files. While most CAD systems can output STL files, they cannot read them. Consequently, CAD users are unable review their STL files before they send them to an RP machine for part production. Sometimes, STL files contain flaws and require repair.

The lack of STL viewing and editing capabilities has spawned the development of a new group of software: Software products and utilities that permit you to read, view and edit STL files. Several have become available over the past couple of years. The following products and companies are listed at random.

SolidView for Windows. SolidView enables you to view, measure, and manipulate STL files. It also permits you to view a model in a number of shaded and wireframe forms, as well as rotate, scale, and position it. I found the product exceptionally fast and easy to use. Price: $1,995.

Solid Concepts Inc., 28231 Avenue Crocker, Unit #10, Valencia, California 91355, (805) 257-9300, Fax (805) 257-9311

Rapid Prototyping Module (RPM). This product enables you to view, render, detect problems such overlapping polygons, reverse normals, detect and repair holes, cut models to create two STL files, and so on. RPM is available as a stand-along product, as well as integrated into Surfacer, Imageware's flagship product. RPM stand-alone (Unix): $12,000. RPM stand-alone (Windows NT and Windows 95): $7,995.

Imageware, 313 N. First Street, Ann Arbor, Michigan 48103, (313) 994-7300, Fax (313) 994-7303

TopologyBuilder-RP. This product permits you to view STL files and correct flaws such as gaps, overlaps, and other common defects that can reduce model quality or prevent you from building an RP part. The product was co-developed by XOX Corporation and Stratasys, Inc. (Eden Prairie, MN), makers of the Fused Deposition Modeling (FDM) rapid prototyping process. TopologyBuilder-RP is based on XOX's SHAPES geometry engine, as well as extensive customer experience with STL files at Stratasys.

XOX Corporation, Two Appletree Square, Suite 334, Minneapolis, Minnesota 55425, (612) 854-3087, Fax (612) 854-6337

Pogo 3.0. This product permits you to view, render, rotate, scale, move, and copy STL files. It also combines multiple ASCII and binary STL files into a single file. Pogo 3.0 converts STL to DXF and OBJ, and vice versa. The software is a 32-bit application that runs under Windows 3.1, Windows NT and Windows 95. Price: $3,500

POGO International, Inc., 7607 Eastmark Drive, Suite 242, College Station, Texas 77840, (800) TRY-POGO, Fax (409) 696-2143

Facet Pro by Cramer Coil & Transformer Corp. This product is an ADS application that works with AutoCAD Designer 1.0 and 1.2, as well as AME 2.1. Facet Pro permits you to read binary STL files into AutoCAD and output both binary and ASCII STL files. Versions are available for Release 12 (DOS and Windows) and Release 13 (DOS, Windows and Windows NT). Price: $495

MasterGraphics, 20875 Crossroad Circle, Waukesha, Wisconsin 53186, (414) 785-9495, Fax (414) 785-1856

You can also read STL files into AutoCAD using AutoLISP. Jim Ten Hoven of Kohler Company (Kohler, Wisconsin) wrote a short AutoLISP routine a few years ago that reads ASCII STL files into AutoCAD. The AutoLISP code was published in the November 1992 issue of CADENCE in the article titled STL Is the Key to Rapid Prototyping.

Appendix B: RP system manufacturers that sell products in the US

3D Systems, Inc., 26081 Avenue Hall, Valencia, CA 91355, (805) 295-5600, Fax (805) 295-0249

BPM Technology, Inc., 1200 Woodruff Road, A-19, Greenville, SC 29607, (803) 297-7700, Fax (803) 297-7711

Cubital America Inc., 1307F Allen Road, Troy, MI 48083, (810) 585-7880, Fax (810) 585-7884

DTM Corporation, 1611 Headway Circle, Building 2, Austin, TX 78754, (512) 339-2922, Fax (512) 339-0634

Helisys, Inc., 24015 Garnier Street, Torrance, CA 90505, (310) 891-0600, Fax (310) 891-0626

Sanders Prototype, Inc., P.O. Box 540, Pine Valley Mill, Wilton, NH 03086, (603) 654-6100, Fax (603) 654-2516

Soligen, Inc., 19408 Londelius, Northridge, CA 91324, (818) 718-1221, Fax (818) 718-0760

Stratasys Inc., 14950 Martin Drive, Eden Prairie, MN 55344-2019, (612) 937-3000, Fax (612) 937-0070

Copyright 1995 by Wohlers Associates