DIAMET

Diamet Corporation is a Japanese manufacturer specializing in powder metallurgy and sintered metal products, headquartered in Niigata City, Niigata Prefecture. The company traces its origins to 1944, when the Niigata plant of Mitsubishi Materials began operating a sintered parts business. In December 2005, that plant was spun off into a joint venture with Plansee Holding and incorporated as Mitsubishi Materials PMG Corporation. In December 2009, the joint venture with Plansee was dissolved, the company became a wholly owned subsidiary of Mitsubishi Materials, and its name was changed to Diamet Corporation. Diamet's core products are oil-impregnated sintered bearings and sintered machine parts, along with soft magnetic materials and magnetic material application technology. Its powder metallurgy manufacturing method enables high-precision production with high efficiency, and the company positions itself as a top brand in sintered bearings. Its products are used widely by major automobile manufacturers, and the company has expanded into new fields such as electric vehicles (EVs) and natural energy power generation. The company's history has been turbulent. Quality data falsification issues emerged in 2016 and 2018, leading to costs for corrective measures and quality assurance system improvements. From the fiscal year ending March 2017 onward, Diamet recorded losses and fell into excess liabilities, requiring financial support from Mitsubishi Materials. By the fiscal year ending March 2020, excess liabilities had grown to approximately 17.7 billion yen. In 2020, Mitsubishi Materials agreed to transfer all Diamet shares to Endeavor United No. 2 Investment Limited Partnership, with the transfer completed on December 4, 2020. Shortly afterward, on December 21, 2020, Diamet and its subsidiary PM Techno filed for civil rehabilitation proceedings with the Tokyo District Court, with total liabilities of approximately 60.4 billion yen. The Tokyo District Court issued a decision terminating the civil rehabilitation proceedings on August 6, 2021, after all creditors other than Endeavor United were repaid in full and Endeavor United forgave part of its claims, resolving the excess liabilities. Today, Diamet continues to operate as a powder metallurgy manufacturer under the ownership of Endeavor United. It maintains its headquarters and Niigata plant in Niigata City, a Fujioka plant in Gunma Prefecture, and sales offices in Tokyo and Aichi Prefecture. Its subsidiaries include PM Techno Co., Ltd., Guangdong Daxuanming Powder Metallurgy Co., Ltd. in China, and DIAMET KLANG (MALAYSIA) Sdn. Bhd. The company continues to develop new products, earning awards from the Japan Powder Metallurgy Association, including a 2025 New Product Award for a sintered spur gear for EV cooling modules and a 2024 award for a sintered bushing for electric solenoid valves.

Diamet Corporation's history begins in 1944, when the Niigata plant of Mitsubishi Materials started operations in the sintered parts business. For decades, the plant operated as part of Mitsubishi Materials, producing powder metallurgy products, particularly for the automotive industry. In December 2005, the Niigata plant was spun off and incorporated as Mitsubishi Materials PMG Corporation, a joint venture between Mitsubishi Materials and Plansee Holding. The new company took over the business previously conducted by the Niigata plant. For the fiscal year ending February 2008, the company recorded sales of 26.765 billion yen. In December 2009, the joint venture with Plansee Holding was dissolved, and the company became a wholly owned subsidiary of Mitsubishi Materials. At the same time, its name was changed to Diamet Corporation. In the years that followed, sales gradually declined due to a slow contraction in automotive demand. More seriously, quality data falsification issues came to light in 2016 and 2018, involving the shipment of non-conforming products after inspection data had been altered. The costs of responding to these issues and of building a quality assurance system contributed to continuing losses and excess liabilities from the fiscal year ending March 2017 onward. Diamet received financial support from Mitsubishi Materials. By the fiscal year ending March 2020, the excess liabilities had grown to 17.70771 billion yen. As a result, on September 29, 2020, Mitsubishi Materials reached a basic agreement to transfer all Diamet shares to Endeavor United No. 2 Investment Limited Partnership. On November 25, 2020, a final agreement was reached to transfer all shares effective December 4, 2020. The transfer was completed as scheduled on December 4, 2020, and Diamet left the Mitsubishi Materials Group. However, the company's financial condition had deteriorated severely, and it was unable to repay 55.151 billion yen borrowed from Mitsubishi Materials, which was due in December 2020. On December 21, 2020, just 17 days after the share transfer, Diamet and its subsidiary PM Techno filed for civil rehabilitation proceedings with the Tokyo District Court. The court issued preservation orders and supervision orders the same day. Total liabilities for the two companies amounted to 60.397 billion yen. Mitsubishi Materials commented to Tokyo Shoko Research that whether to choose a legal process was a decision for Endeavor United. A creditors' meeting was held in Niigata City on December 24, 2020. The filing representative stated that general trade claims would be repaid in full, but that payments to large creditors with claims exceeding 20 million yen might be delayed, that a decision to commence civil rehabilitation proceedings was expected on December 28, 2020, and that a rehabilitation plan would be submitted in March 2021. Endeavor United became the civil rehabilitation sponsor and proceeded with reconstruction. On August 6, 2021, the Tokyo District Court issued a decision terminating the civil rehabilitation proceedings for Diamet and PM Techno. All claims other than those of Endeavor United were repaid in full, and Endeavor United forgave part of its claims, resolving the excess liabilities. Since then, Diamet has continued to operate as a powder metallurgy manufacturer. It maintains its headquarters and Niigata plant at 3-1-1 Kogane-cho, Higashi-ku, Niigata City, Niigata Prefecture; a Fujioka plant at 700 Ushida, Fujioka City, Gunma Prefecture, within the Ushida Industrial Park; an East Japan Sales Office at 7th floor, International Fashion Center Building, 1-6-1 Yokoami, Sumida-ku, Tokyo; and a Central and West Japan Sales Office at 5th floor, Karitsu Building, 1-4-4 Mikawa Anjo-cho, Anjo City, Aichi Prefecture. Its subsidiaries include PM Techno Co., Ltd., Guangdong Daxuanming Powder Metallurgy Co., Ltd. in China, and DIAMET KLANG (MALAYSIA) Sdn. Bhd. The company continues to develop new products and has received awards from the Japan Powder Metallurgy Association, including a 2025 New Product Award in the Design Category for a sintered spur gear for EV cooling modules using high-airtightness heat-treated material, and a 2024 New Product Award in the Design Category for a sintered bushing enabling enhanced performance of electric solenoid valves.

• Mitsubishi Materials Niigata plant begins operations in the sintered parts business.

• Niigata plant spun off and incorporated as Mitsubishi Materials PMG Corporation, a joint venture with Plansee Holding.

• Fiscal year ending February 2008 records sales of 26.765 billion yen.

• Joint venture with Plansee Holding dissolved; company becomes wholly owned by Mitsubishi Materials and changes name to Diamet Corporation.

• Quality data falsification issue comes to light.

• Second quality data falsification issue comes to light.

• Mitsubishi Materials reaches basic agreement to transfer all Diamet shares to Endeavor United No. 2 Investment Limited Partnership.

• Final agreement reached to transfer all Diamet shares effective December 4, 2020.

• All Diamet shares transferred to Endeavor United; company leaves Mitsubishi Materials Group.

• Diamet and subsidiary PM Techno file for civil rehabilitation with Tokyo District Court; total liabilities 60.397 billion yen.

• Creditors' meeting held in Niigata City; filing representative outlines repayment plan.

• Tokyo District Court decides to terminate civil rehabilitation proceedings for Diamet and PM Techno.

• Wins 2024 New Product Award / Design Category from Japan Powder Metallurgy Association for sintered bushing for electric solenoid valves.

• Wins 2025 New Product Award / Design Category for sintered spur gear for EV cooling modules.

Top brand in sintered bearings; global industry leader in powder metallurgy technology and products.

• Oil-Impregnated Sintered Bearings

  High-precision, high-quality, high-performance sintered bearings and oil-impregnated sintered bearings manufactured using unique powder metallurgy technology and self-manufactured high-precision die assemblies. Also includes dry bearings for high-temperature or clean environments and corrosion-resistant sintered bearings.

• Sintered Machine Parts

  Sintered machine parts for automobile parts and other applications, featuring high precision and production efficiency.

• Soft Magnetic Materials

  Soft magnetic materials and magnetic material application technology.

• Sintered Spur Gear for EV Cooling Modules

  Using high-airtightness heat-treated material; won 2025 New Product Award / Design Category from Japan Powder Metallurgy Association.

• Sintered Bushing for Electric Solenoid Valves

  Innovative magnetic bushing achieving both excellent sliding performance and magnetic properties; won 2024 New Product Award / Design Category.

1. 1TOP | Diamet Corporationdiamet.co.jp
2. 2Corporate Information | Diamet Corporationdiamet.co.jp
3. 3Products | Diamet Corporationdiamet.co.jp
4. 4Award-Winning Records | Diamet Corporationdiamet.co.jp
5. 5ダイヤメット - Wikipediaja.wikipedia.org
6. 6DIAMET - Wikidatawikidata.org