Ikeuchi Seiko Co., Ltd.
Corporate brand
UnclaimedJapanese specialist manufacturer of secondary steel processing products such as drawn bars, CHQ wire, peeled bars and cut products, based in Yokosuka, Kanagawa.
Last updated September 28, 2026
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Overview
Ikeuchi Seiko Co., Ltd. (池内精工株式会社) is a Japanese specialist manufacturer of secondary steel processing products, headquartered in Kurihama, Yokosuka, Kanagawa Prefecture. The company was founded in September 1939 in Okurayama, Yokohama, with capital of 500,000 yen, and has since developed into a dedicated maker of processed steel materials used by downstream manufacturers in automotive, office automation and general machinery sectors. Its core product lines include drawn bars, CHQ (cold heading quality) wire, peeled (turned) bars and cut products. These are produced from steel supplied by steelmakers and processed to states suitable for machining and cold forging, where precision and strength are critical quality factors. The company describes itself as a specialist in secondary steel processing and emphasizes high precision enabled by its dedicated manufacturing focus, supported by substantial equipment and quality assurance systems. It operates under the slogan of pursuing customer needs — "Best and More" — and states that it works with steelmakers from the material stage to develop products matched to customer requirements. Its quality management system has been certified to ISO 9001 since 2002, with updates in 2010 and 2017. In 2023 it obtained EcoAction 21 certification and registration (certification number 0013929), reflecting its environmental management efforts. The company also participates in regional initiatives such as the Kanagawa Health Company Declaration (entry in 2024) and was designated a Kanagawa SME Model Factory in 2015. Historically, Ikeuchi Seiko began by manufacturing ground steel bars and various components processed from them. In 1952 it developed a ground steel bar drawing device (patent No. 208797). In 1961 it discontinued component manufacturing to concentrate on being a specialist ground steel bar maker, expanding its polishing and heat treatment departments. A major rationalization program began in 1964, including rebuilding all plants and introducing coil-to-bar drawing and peeling machines, completed in 1971. In 1978 it entered the cold heading quality steel wire field in response to changes in component forming methods. In 1986 the head office and plant were fully relocated to Kurihama, Yokosuka, accompanied by expansion of continuous drawing machines, an automated pickling line, a new heat treatment furnace and additional peeling machines. In 2000 the logistics division was separated and incorporated as Ikeuchi Kosan Co., Ltd. In 2010 the company established Ikeuchi Dingfeng (Foshan) Precision Processing Co., Ltd. in Foshan, Guangdong Province, China, marking an overseas manufacturing presence. Subsequent investments included additional roller hearth annealing furnaces in 2009, 2015 and 2018, a new No. 5 plant (Uchikawa Plant) in Yokosuka in 2017, and in 2019 an additional pickling line and a new wire drawing machine. The company remains privately held and is led by President Keiichiro Yamaoka. Its operations are centered on its Yokosuka plants, with a Chinese subsidiary supporting its international footprint.
History
Ikeuchi Seiko was established in September 1939 in Okurayama, Yokohama, with capital of 500,000 yen, as a manufacturer of ground steel bars and various components processed from them. In 1952 it developed a ground steel bar drawing device, patented as No. 208797. In 1958 it was designated a Small and Medium Enterprise Rationalization Model Factory, a designation it held until 1960. In 1961, to concentrate on its role as a specialist ground steel bar manufacturer, it discontinued component manufacturing and expanded its polishing and heat treatment departments. A major rationalization program began in 1964, involving the rebuilding of all plants, introduction of coil-to-bar drawing and peeling machine equipment, and renewal of bar-to-bar drawing equipment; the program was completed in 1971. In 1978, responding to changes in component forming methods, the company entered the field of cold heading quality steel wire. In 1986, it fully relocated its head office and plant to Kurihama, Yokosuka, and carried out a rationalization plan that included adding continuous drawing machines, an automated pickling line, a new heat treatment furnace and additional peeling machines. In 2000, the logistics division was separated and incorporated as Ikeuchi Kosan Co., Ltd. In 2002, the company obtained ISO 9001:2000 certification (registration number JQ1013A). In 2006, peeling machines and straightening machines were added. In 2009, two roller hearth annealing furnaces were added. In 2010, it established Ikeuchi Dingfeng (Foshan) Precision Processing Co., Ltd. in Foshan, Guangdong Province, China, and updated its ISO 9001 certification to the 2008 version. In 2015, one roller hearth annealing furnace was added, and the company was designated a Kanagawa SME Model Factory. In 2017, it acquired land and buildings in Uchikawa, Yokosuka, established the No. 5 Plant (Uchikawa Plant), and obtained ISO 9001:2015 certification (registration number JQ1013F). In 2018, two roller hearth annealing furnaces were added at the No. 5 Plant. In 2019, an additional pickling line and one new wire drawing machine were installed. In 2023, the company obtained EcoAction 21 certification and registration (certification number 0013929). In 2024, it entered the Kanagawa Health Company Declaration (dated April 8, 2024). As of 2026, it published a recruitment PR video. The company remains privately held and is led by Representative Director and President Keiichiro Yamaoka.
Founded in Okurayama, Yokohama, with capital of 500,000 yen; began manufacturing ground steel bars and processed components.
Developed a ground steel bar drawing device (patent No. 208797).
Designated a Small and Medium Enterprise Rationalization Model Factory (until 1960).
Discontinued component manufacturing to focus on ground steel bar specialization; expanded polishing and heat treatment departments.
Began full plant rebuilding and rationalization program including coil-to-bar drawing and peeling machines (completed 1971).
Entered the cold heading quality steel wire field.
Fully relocated head office and plant to Kurihama, Yokosuka; expanded equipment.
Separated and incorporated logistics division as Ikeuchi Kosan Co., Ltd.
Obtained ISO 9001:2000 certification (registration number JQ1013A).
Added peeling machines and straightening machines.
Products and positioning
Specialist manufacturer of secondary steel processing products, emphasizing high precision, quality assurance and customer satisfaction in quality, price and delivery.
Drawn Bar
Drawn products made from special steel, tempered steel and other hard-to-machine materials, up to ultra-high-precision materials for office automation applications.
CHQ (cold heading quality) wire
High-quality cold heading quality steel wire produced with one of Japan's leading large-diameter wire drawing machines and reproducible annealing furnaces.
Peeled Bar
Peeled bars produced by turning the material surface, free from surface scratches and decarburization, with low internal stress.
Cut Products
Cut products delivered with cutting surfaces and precision optimal for customer applications; pipe cutting also available.
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