For RP equipment, the primary needs, regardless of country, are lower equipment cost, lower maintenance costs, greater accuracy, better surface finish, and higher speed; however, relative importance of these factors does vary.

Equipment Costs

While some new U.S. equipment makers are focusing on lowering costs, such as for desktop RP units, the drive to develop low-cost equipment does not appear to be a major consideration in Europe. The European equipment maker EOS is positioning itself as a high-cost premier producer of equipment, and Cubital units have been consistently at the high end of the cost range.

In Japan, RP equipment equivalent to that available in the United States is considerably more expensive. In comparison, machine tool centers in the same size class as an RP machine are less expensive than stereolithography units. Yet, inexpensive, albeit lower-accuracy, units are available for the jewelry industry from such companies as Meiko, which produces a photo resin-based unit with a price tag of ~$140,000, including software. For some Japanese equipment makers, lowering equipment costs is becoming an objective. D-MEC representatives mentioned price as a customer concern; consequently, this Japanese company plans to develop lower-cost machines in the future.

Maintenance Costs

For RP equipment using lasers, the lasers themselves can be the highest maintenance cost item. Fockele and Schwarze (Sites, 1996, 14-17) has been evaluating diode-pumped Nd lasers with frequency triplers to replace the argon ion lasers that are more expensive to maintain. EOS has been offering these diode-pumped Nd lasers commercially on its STEREOS MAX laser stereolithography units for some time and has sold several such systems to customers. Diode-pumped Nd lasers are expected to have longer life, be less expensive to replace, and consume less power.

In Japan, maintenance contracts appear to be comparable in cost to those in the United States, but resins are much more expensive.

Accuracy and Surface Finish

Improvement of accuracy and surface finish are often primary considerations for users of RP equipment. As more companies attempt to build prototype plastic injection mold cavities by RP, the need for greater accuracy and surface finish in the RP master copy will increase, since some degradation of part dimensions occurs in the injection molding process.

Daimler Benz representatives indicated that with stereolithography they can routinely achieve 100 micron accuracy in the x-y direction and 250 microns in the z direction. They would like 70 micron accuracy in all three directions. (Such tolerances are already achievable in the United States.) JTEC/WTEC panelists talked with observers of the European RP industry who indicated that it is not always clear what user needs are for accuracy in a prototype part; in some cases, current dimensional tolerances are sufficient.

Stereolithography is the most popular RP method in use in Japan. When panelists asked why selective laser sintering units are not as popular in Japan as in the United States, the explanation offered was that stereolithography provides the greatest accuracy. Generally, Japanese companies would like to see higher accuracy capabilities, where tolerances of ±0.03 mm can be routinely achieved (Sites, 1996, CMET and Olympus site reports, 42-46, 95-98). Representatives of Shonan Design Company, a service bureau, mentioned to panelists that their customers indicate they will increase orders for RP parts as accuracy and surface finish improve.


Speed appears to be an important consideration in Europe, as shown by the fact that BMW underwrote the first EOS stereolithography unit based on a speed-performance standard. Automaker Daimler Benz would also like to see speed increases in the recoating operation, and other companies indicated that speed is an important consideration.

Compared to the United States, less consideration appears to be placed on speed in Japan. As an example, less emphasis is placed by some Japanese RP equipment manufacturers on providing software to automatically design structural supports for the parts being built, leaving customers to laboriously design supports by manual techniques (Sites, 1996, CMET/Asahi Denka report, 42-46). However, a Sony representative did mention speed as one attribute of Sony's next-generation RP machines (Sites, 1996, D-MEC report, 47-53).

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Published: March 1997; WTEC Hyper-Librarian