Date Visited: 13 December 1995
JTEC/WTEC Attendees: M. Wozny (report author), C. Atwood, E. Sachs, Mamiko Nozaki, Interpreter
Nakamura Pattern Making Company (hereafter, Nakamura) is a user of rapid prototyping technology, as opposed to being a developer. The company makes wood patterns and core boxes primarily for sand casting. Founded in 1949 by the senior Mr. Nakamura (father of the JTEC/WTEC team's host), the company is a true SME (small to medium enterprise, usually having fewer than 500 employees) that employs 20 people at two sites. About 80% of the company's products are produced for Nakamura's parent company, Toyoda Machine Works (hereafter, Toyoda). Team members were very impressed with the modern as well as extensive capabilities of such a small company.
Our host, Mikio Nakamura, uses rapid prototyping technology to compensate for the continually decreasing availability of skilled pattern makers. With fewer young people attracted to skilled craft careers, the average age of his workforce is now 50 years and aging. Nakamura indicated that he has had an active training program in the past (to train younger workers), but they were not interested in careers as pattern makers. He also uses rapid prototyping technology for handling complex and intricate shapes.
By avocation, Mikio Nakamura is a master calligrapher.
Nakamura introduced computer-based technology (CAD and NC) in 1960, at a time when manual labor by skilled pattern makers was generally faster and cheaper. CAD usage developed quickly. NC, originally restricted to patterns with complex shapes, evolved with experience into a "great technology." The quality of NC patterns has evolved to the point where they are superior to that of handmade patterns produced by skilled pattern makers.
Nakamura installed rapid prototyping technology in July 1995 -- the Helisys LOM-2030TM (LOM, Laminated Object Manufacturing, is a registered trademark of Helisys). Prior to making this decision, representatives of Nakamura and Toyoda attended the Society of Manufacturing Engineers (SME)-sponsored Rapid Prototyping Conference in Dearborn, Michigan, and then visited Helisys, Ford, and another user of LOM technology. The visitors were very impressed (in fact, "shocked") by the wide range of applications and ease-of-use of the LOM machine. At the time, Toyoda was establishing an LOM demonstration center. (At the time of the JTEC/WTEC visit, there were more than 12 LOM machines in Japan.) Toyoda is the Japan partner of Helisys, providing demonstration, sales, distribution, and technical service.
The Helisys LOM-2030 produced a 30 cm high motor casing in about 48-50 hours. Drying and all other finishing operations took about one additional day.
Nakamura chose LOM technology because it reinforces the company's deep knowledge and experience in wood pattern making. The technology fits the application. Nakamura staff has found LOM easy to operate, requiring minimal training. "NC has more factors to consider, like jigs and fixtures, and tool path programming." Nakamura's workers need five years of experience before they can use NC productively. LOM is productive "right from the beginning," requiring only four months' experience. Furthermore, the patterns require minimal post-processing (finishing). Reliability and accuracy are the other major considerations.
Nakamura shunned other technologies because they were either too expensive, exhibited too much distortion (difficult to get "even thickness"), or did not enhance the existing capabilities and experience. At the other end of the spectrum, low-cost technologies were also judged inadequate, because of the relatively lower quality of the sheet material (paper) and less accurate cutting. Inexpensive machines that do not increase accuracy simply transfer the cost from producing the raw part to extensive post-processing.
For common patterns, manual production is generally cheaper and faster. Nakamura uses LOM when the shape is too complex or the appropriate skill level is unavailable.
Nakamura gains a competitive advantage by combining the strengths of both LOM and NC technologies: the speed, ease-of-use, and lesser experience requirement of LOM, with the high accuracy of NC. NC machines operate 16 hours a day, while LOM runs 24 hours a day, much of that time unattended.
The second factory site (LOM, NC, CAD) supports five workers performing 3D CAD, NC, LOM, and finishing operations. The site has three NC machines, four CAD stations, and the LOM machine. The availability of the LOM machine has attracted more customers, increasing business volume by 50%.
Nakamura desires more accuracy from LOM technology. NC milling and grinding easily achieve accuracies of ±0.1 mm. LOM's accuracy, "out of the machine," is about ±0.25 mm. LOM requires much finishing work to achieve accuracies of ±0.1 mm in a 60 cm x 50 cm x 50 cm volume, especially those regions that have contact with the customer's component.
Using thinner paper layers does not solve the accuracy problem. The corresponding increase in build time is much too long for the benefits gained, since the desired accuracy is still not achieved and the same finishing effort is required.
Care is taken to control errors. Temperature and humidity are controlled, and sealers are used to minimize the shrinking (or swelling) of the final part.
Due to the stair-stepping effect of the layer-additive LOM process, the highest quality patterns are still made of wood.
Nakamura has more than 10 years experience in 3D CAD. This capability evolved naturally from the staff's knowledge of wood pattern making. Nakamura has three different CAD systems: ProEngineerTM, a U.S. commercial 3D system; CaelumTM, developed by Toyota Motor Company and used by Toyota and its suppliers; and TAPROS 3000, a part-programming system developed by Toyoda. (ProEngineer is a registered trademark of Parametric Technologies, Inc.; Caelum is a registered trademark of Toyota Caelum, Inc.)
Mikio Nakamura estimates that 3D CAD usage in Japan is well behind that in the United States. In Japan, more than 80% of CAD usage is for two-dimensional drawings, while less than 20% is for three-dimensional modeling.
Mikio Nakamura believes strongly that his advantage in achieving full utilization of LOM is based on a thorough and deep knowledge of wood pattern making. He expected to add another rapid prototyping machine within the next 12 to 18 months.
We thank Mikio Nakamura and his parents for being gracious hosts. We thank Mikio Nakamura for sharing his time and knowledge with us freely and openly.