Site: Mizuno Corporation
R&D Department, Product Development Div.
12-35, 1-chome, Nanko-kita
Suminoe-ku, Osaka, Japan
Date Visited: December 9, 1992
Report Author: B. Kramer
Mr. Kazuhiro Ohmori
Mr. Toshihiro Inubushi
Mr. Takeshi Naruo
Mr. Takashi Ito
Mr. Rick Tsuruoka
Ms. Chikako Kamimukai
Mizuno, founded in 1906, is a leading manufacturer of general sports equipment. They manufacture all of their sports equipment internally. The JTEC team had discussions in the new headquarters building, but did not visit the production facility.
The discussions at Mizuno were largely limited to a question and answer period.
Concerning golf shafts, U.S. shafts are 10% carbon fiber, while Japanese shafts are 50% carbon fiber. Mizuno produces golf shafts by sheet rolling. They use graphite in skis, tennis rackets, baseball bats, and sports shoes. They use 20 different kinds of carbon fiber, both PAN and pitch types. They have used graphite springs in shoes for five years and usage is not growing. They are not producing carbon-fiber bicycle frames now, but may be developing them. When asked why they decide to use composites in a given product, they indicated that it is very strong when compared to wood or steel.
Mizuno compression molds skis and blow molds graphite baseball bats (they consider themselves to be the leader) and tennis rackets with an expanding rubber bladder. They use computer analysis extensively, particularly for skis and golf shafts. Manufacturing is highly automated, with both robots and in-process sensing. Total waste amounts to only 2-3% of the composite sheet.
Mizuno considers SRIM (structural reaction injection molding) for tennis rackets to be a key technology for the future because it is a non-solvent process, and is completely automated and repeatable. They claim 60% by weight fiber content in SRIM and indicated that cross-linked polyesterimide is the best SRIM resin. All of their professional tennis rackets (20% of total production of 100,000 per year) are SRIM; the remainder are blow-molded.
Mizuno uses all kinds of hybrid fibers, preformed by braiding. Their process development emphasized steady improvement, rather than breakthroughs. They pick new products by looking for applications where high performance composites give real benefits. For example, large head tennis rackets cannot be fabricated from wood or metal because of their relatively lower stiffness.
Mizuno Corporation. 1992. "Mizuno The World of Sports" (Japan).