Site: Mitsubishi Electric Co. (MELCO)
Materials & Electronic Devices Laboratory
1-1, Tsukaguchi-Honmachi 8-chome
Amagasaki, Hyogo 661, Japan
Date Visited: December 11, 1992
Report Author: B. Kramer
MELCO started producing glass & fiber-reinforced radar domes in 1955 and began applying composites to satellites in 1970. The company is now one of the biggest satellite manufacturers in Japan. It develops all of its own composites technology for satellites. A synthetic aperture radar launched in 1992 has eight panels, 2.2 m x 1.4 m each with 1 mm form accuracy. The Intelsat VII, C-band antenna is 2.44 m diameter, with 0.15 mm accuracy. Heat pipe panels are produced up to 2.4 m x 2.8 m in size. Large solar panel arrays are also produced.
(MITI research project -- approximate cost of $1 million for the machine)
The machine combines filament winding and pultrusion with high E fiber and epoxy resin, achieving 60% fiber volume fraction. Production rate is 1-5 m/hr. It uses prepreg tape, approximately 50 meters on each tape spool.
MELCO currently uses 2.5-D preforms. The 3-D composites research consortium was started five years ago with 10 researchers from five companies (NSC, Toyoda, Mitsubishi Rayon, and Arisawa and MELCO) and $16 million in funding for six years (70% government & 30% companies).
It is believed that the most promising technologies are four-step braiding and four- axis and five-axis braiding. Mr. Murayama is very knowledgeable about braiding. MELCO has good capabilities in cylindrical braiding and has a parabola weaving machine that is patented. A 3-D knitting machine is under development by Asahi Kasei.
Our MELCO hosts stated that they cannot rate their company relative to other companies, since they have not seen other companies. They use CAD/CAM, and their best manufacturing technologies are accurate filament winding (better than anyone else) and very lightweight structures. They think there may be a good future for composites, if applications can be developed. RTM is a potential breakthrough technology in the mid-volume area (not refrigerators). The main problem in 3-D weaving is production rate and no solution is in sight; 2.5-D might provide a partial solution.
MELCO uses supplementary oil heating on autoclave tooling and produces very flat solar cell panels with excellent seams. Our hosts expressed the view that design for the total system of composites is very important, since conventional design systems are oriented towards metals. They feel the key element is more imaginative, creative people.
Our hosts indicated that U.S.-Japanese cooperation could help increase the use of composites and they are interested in continued cooperation. They have good cooperation with their suppliers, but communications with other manufacturers is on a person-to-person basis only.
For widespread use, low fiber cost is not critically needed. It is more important to reduce finished cost to 2-3 times raw material cost, instead of 10-50 times.
Mitsubishi Electric Co. 1992. "The Sagami Works 1992 Corporate Profile."
------. "Space Activities" (brochure).