MMC Magazine

Mitsubishi Materials Advanced Materials & Tool Company began with the manufacture of the TRIDIA carbide tool in 1931, and the Tokyo Plant played a central role in the history of the tool. It was not so common to have such a plant in the middle of Tokyo and the Mitsubishi Materials Tokyo Plant witnessed the pre- and post-war periods, the high growth period and the bubble economy as it grew into a base for the manufacture of carbide tools.

Beginning of Carbide Alloy Processing

The Tokyo Plant was located where Shinagawa Chuo Park now stands. At the centre of Tokyo just a few minutes on foot from the Shimo-shimmei Station on the Tokyu Oimachi Line, the Tokyo Plant operated from 1916 until about 25 years ago. Mitsubishi Materials’ carbide tool business started 100 years ago in 1916, back when the Mitsubishi Goshi Kaisha Mining Research Institute (Central Research Institute) was established as a private company research institution, which was based on a proposal by Koyata Iwasaki. The institute engaged in research on tungsten ahead of other companies. In 1923, it began research on carbide alloys. In 1926, the German company, Krupp, launched WIDIA, the world’s first carbide tool. The surprising cutting performance prompted companies around the world to also accelerate their research on carbide alloys. A member of the staff at the Central Research Institute that was in England at the time, was awestruck when he witnessed the performance of WIDIA’s product. Mitsubishi Materials immediately realised the potential of carbide alloys and pushed development. Overcoming obstacles proved to be a prodigious challenge, forcing the company to toil eight long years before the launch of its first carbide product, TRIDIA, in 1931. When Mitsubishi Materials relocated the Mining Research Institute to Omiya, the carbide alloy development business remained and continued operating as the Oi Branch.

The Mining Research Institute at the time of foundation Research on carbide alloys started in this building. / A commemorative picture taken in 1937 / New 6-story building responding to mass production / The Tokyo Plant in the strong economic growth period (around 1960) / The Tokyo Plant that was repeatedly remodeled and expanded / Working with CAD systems

Severe business conditions during the war

The start of World War II in 1939 had an immediate impact on the industry. The demand for war supplies such as cemented carbide and stellite increased whilst employees were sent to the war front.

By 1943, monthly production of cemented carbide had exceeded 1 ton and stellite production exceeded 3 tons. It was at this time that the plant became independent from the Mining Research Institute. Continuing operations as the Tokyo Metals Plant, it was soon designated as Important National Plant. The plant was damaged in 1944 when allied air raids hit the city; and after the war, it was listed as a possible asset to be included in post-war reparations and faced the risk of confiscation. The plant avoided that fate however and employees worked hard to restart production. The carbide tool business had been on track for success, but the war derailed it; conditions after the war meant that no other companies could consider buying it or even investing in it, which worsened Mitsubishi Materials’ situation considerably. The top management was forced to consider reducing production and laying off employees; but the labour union resisted this plan, insisting that if cutting production forced the layoff of even one employee, the plants should be closed. In the end, on October 31, 1948, Mitsubishi Materials had no choice but to lay off most of its employees, retaining only the minimum number required to maintain the plants and their technology, but hoping that they would be able to re-instate them soon. The company continued developing mining tool bits for Europe and the U.S. and strived to return the company to its pre-war status.
In December of the same year, 1948, the plants reopened and the laid-off employees were immediately called back.

Economic growth and the bubble economy

In 1952, the Tokyo Metals Plant was renamed the Mitsubishi Metal Mining Company Ltd. Oi Plant. After a period of robust economic growth, the company moved into the black for the first time after the war in 1955. Following this, it increased production gradually, achieving record profits for three consecutive terms from the first half of 1967 through to the first half of 1968. The plant grew into a major business that supported the entire company. In 1969, the company built its Gifu Plant, realising that although they could become the top company in Japan with the Oi Plant, the Oi Plant alone would not allow it to become the world’s No. 1 company. In 1970 the Oi Plant was renamed into Mitsubishi Metal Corporation Tokyo Plant. It was 35 years since the launch of TRIDIA and a turning point at which the company decided to introduce its carbide business to the global market.

The Tokyo Plant before the shift to the Tsukuba Plant (around 1986) / Designing tools / The site is currently occupied by Shinagawa Chuo Park.

The spirit of the past handed down to the present

Through the shift from the Mitsubishi Metal Mining Company Ltd. Oi Plant to the Mitsubishi Metal Corporation Tokyo Plant, the carbide tool business continued to grow. Facing the challenge of a significant expansion in demand over such a short period of time affected customer services and product development capability. Because of its location in urban areas, it was hard to expand facilities, which impacted the company’s ability to expand business, including employee service and benefit programs. To address this situation, management discussed relocating the Tokyo Plant to Ishigemachi in Yuki County (present day Joso City) near Tsukuba Scientific City in Ibaraki Prefecture. The Tokyo Plant was relocated to the Tsukuba Plant site in March, 1992. The spirit of independence and striving ever forward helped the Tokyo Plant to survive hardship. This spirit has been carried on by all employees. It has been 85 years since Mitsubishi Materials commercialised cemented carbide tools under the product name of Tridia in 1931. We continue to pass what they have achieved in the past 85 years onto the next 100 years aiming for further development.