Proterial (ex-Hitachi Metals)

Sintered NdFeB sold under the NEOMAX brand, plus ferrite magnets, supplied mainly into EV traction and auxiliary motors, industrial motors and electronics. The magnet line descends from Sumitomo Special Metals, where Masato Sagawa's team filed the founding sintered NdFeB composition patent with an August 1982 priority date. Magnets are one part of a diversified group that also makes specialty steel, rolls, power electronics, wires and cables and automotive components.

At a glance

Founded: 1956 — Established April 1956 as Hitachi Metals Industry, spun out of Hitachi, Ltd. A Bain Capital-led consortium closed its tender offer on 25 October 2022, the company was delisted from the Tokyo Stock Exchange on 29 December 2022, and it was renamed Proterial on 4 January 2023.
Headquarters: Tokyo, Japan
Ownership: Private. Wholly owned by the acquisition vehicle of a consortium of Bain Capital Private Equity as lead, with Japan Industrial Partners and Japan Industrial Solutions. Delisted from the Tokyo Stock Exchange on 29 December 2022.
Stage: Mature. The company that invented sintered NdFeB, producing in Japan for decades.
Listing: Private. Private since the Bain Capital-led buyout closed in 2022; delisted.
Revenue: JPY 747.3 billion
Reported, fiscal year ended 31 March 2026.
Published by the company on its own corporate summary page. Magnets are one part of a diversified materials group and are not broken out. Proterial has been privately held since 2022 and files no statutory annual report, so this figure is company-published rather than filed.
Source

Capacity

Each date below links to the document the figure came from. A capacity figure with no source is not on this page.

What	Figure	Status	As of
Sintered NdFeB and ferrite magnet lines, Kumagaya Works, Saitama, Japan — a new building and production lines under an approximately JPY 18 billion investment, scheduled to start in FY2018	tonnage not disclosed by the company	Operating	Oct 2016
Sintered NdFeB magnets for traction motors — reported by Benchmark Mineral Intelligence, not published by the company. The source names no country and no plant, and does not say whether the China plant below is inside or outside this figure	2,500-3,000 t/yr	Operating	Jan 2026
Sintered NdFeB, China plant — reported by trade press, not published by the company	more than 2,000 t/yr	Operating	Aug 2025
Sintered NdFeB, Achutapuram, Andhra Pradesh, India — reported via Indian press citing a state investment committee; no Proterial release confirming the project was located	1,200 t/yr	Announced	Jun 2026

Narrative

Proterial is the corporate successor to Hitachi Metals, which renamed itself on 4 January 2023 after a Bain Capital-led consortium took it private. Its magnet business descends from Sumitomo Special Metals, where Masato Sagawa's team filed the founding sintered NdFeB composition patent in August 1982; that lineage passed through NEOMAX, which merged into Hitachi Metals in April 2007. The company licensed sintered NdFeB production worldwide and brought a 2012 US International Trade Commission action against importers, settling before trial with fourteen licensees by mid-2013. It sells NdFeB under the NEOMAX brand and expanded magnet lines at Kumagaya Works from FY2018. Having been private since 2022 it files no statutory annual report; it published group revenue of JPY 747.3 billion for the year to March 2026 on its own corporate summary page. In 2026 it was reported to be planning a plant in Andhra Pradesh, India.

Where public sources disagree

There is no statutory filing to check this against. Proterial's last annual securities report on EDINET, Japan's disclosure system, covers the year to March 2023 and was filed in June 2023; after the buyout its bonds are privately placed, so it is no longer a continuous-disclosure company. Revenue since then is company-published only.
Two different revenue figures for Proterial are in circulation and both come from the company. Its investor-relations financial-highlights page still shows JPY 1,033.2 billion and has not been updated past the year to March 2024; its corporate summary page gives JPY 768.6 billion for the year to March 2025 and JPY 747.3 billion for the year to March 2026. These are the same line item on the same basis. The higher figure is stale, not wrong.
Part of the decline is accounted for by disposals rather than by trading. Ward Manufacturing was sold with effect from February 2024 and the piping equipment division was sold to Okaya with completion inside the year to March 2025; over the same period the corporate summary drops Piping Components from its business list, plants fall from nine to eight and consolidated headcount falls from 21,456 to 18,877. Neither party disclosed the revenue of the divested units, so how much of the fall they account for is not public.
No company-published tonnage exists for any Proterial magnet plant. Two third-party figures circulate and they cannot be added together. A trade report gives more than 2,000 metric tons for the China plant. Benchmark Mineral Intelligence reported on 13 January 2026 that Proterial "produces 2,500-3,000tpa of sintered NdFeB magnets for traction motors"; that sentence names no country and no plant, covers traction-motor products rather than the whole magnet business, and does not say whether the China plant is inside or outside it. The two figures overlap by an unknown amount, and neither is a company disclosure.
The patent story is often compressed inaccurately. The last basic compositional patent in the Sumitomo family expired in July 2014, but later Hitachi Metals process and composition patents ran to 2021 and 2022 and were the ones asserted in the 2012 trade case. The statement that the NdFeB patents expired in 2014 is true only of the basic composition claims.
Sources differ on the invention date: the patent record carries an August 1982 priority date, while general reference works often date the independent discoveries to 1984, which is usually the date of public announcement rather than of filing.
The India project is reported via Indian trade and general press citing a state investment committee, with no Proterial release located. In 2025 the company told a reporter it has a policy of not disclosing the status of investment considerations.

Fact checks from the digest

Claims made about this company that the weekly digest has put against this atlas, newest first. The verdict and the working are here in full; the issue each came from is for subscribers.

contested · Digest issue 006 · 28 September 2026

Somebody finally published a number for Japanese magnet capacity

Both figures go on the atlas and neither is treated as settled, for four reasons that have to be said before anybody builds a plan on them.
Neither is a Japanese figure. Shin-Etsu's 3,400 tpa is explicitly Japan and Vietnam combined, and Benchmark publishes no split. Shin-Etsu's own only published magnet tonnage is 2,200 t/yr for Vietnam, from June 2017 — a floor of unknown currency. Subtracting one from the other to get a Japanese number is not supported and the atlas does not do it. The Proterial figure carries no country and no plant at all.
The Proterial number is segment-qualified. “For traction motors” is a floor for the company, not a nameplate, and Proterial's magnet business is wider than traction motors. It also cannot be added to the trade-reported more than 2,000 t/yr for its China plant, because nothing says whether China sits inside or outside it.
These are analyst assertions. Benchmark credits no primary source and neither company has published the figures. They go on the page as press reporting, attributed, not as disclosed capacity.
And they are contested by figures I cannot print. Private market intelligence circulating in this industry puts Shin-Etsu's combined total far higher — different by roughly a factor of seven. I have no public document for that, so it does not appear here as a number. What this changes is the shape of the argument: until this week it was an unpublished private claim against silence. Now it is an unpublished private claim against a dated, citable, attributable figure, and that is a better position to argue from even though nothing is resolved.

Sources

Corporate summary — the company's current revenue figures — Proterial, Ltd. (accessed 2026-09-18)
Corporate summary archived July 2025, showing JPY 768.6 billion for FY3/2025 — Proterial, Ltd. via the Internet Archive (2025-07-22)
Financial highlights — last updated for the year to March 2024 — Proterial investor relations (accessed 2026-09-18)
Sale of Ward Manufacturing, LLC (Japanese) — Proterial, Ltd. (2024-02-02)
Notice concerning change of trade name — Hitachi Metals via Business Wire (2022-09-26)
Completion of tender offer for Hitachi Metals shares — Hitachi, Ltd. (2022-10-26)
US 5,645,651 — Sagawa, Fujimura, Matsuura; assignee Sumitomo Special Metals; priority 21 August 1982 — Google Patents / USPTO (1997-07-08)
Boosting production capacity for NdFeB and ferrite magnets, Kumagaya Works — Green Car Congress (2016-10-27)
Proterial looks to India for rare earth magnet manufacturing — Mint, reprint hosted by Primus Partners (2025-08-06)

How this page is sourced

Everything here comes from public sources — company filings, annual reports, exchange announcements, government releases and trade press. Every figure is linked to the document it came from and carries the date that document was published, because a capacity number without a date is not a fact, it is a rumor with a decimal point.

What is deliberately absent: material nonpublic information. I have spent more than two decades in this industry and a good deal of what I know about these companies I learned under NDA. Those obligations do not expire and they do not bend for a website. Nothing I have been told in confidence appears here in any form, and nothing on this page — or missing from it — should be read as a signal about what I know privately. I hold NDAs absolutely. It is the reason clients tell me things.

Judgment is the other thing left out on purpose. This page reports what has been published and who published it. Whether a target is credible, whether a ramp will hold, whether a capacity figure survives contact with the plant behind it — that is the work I do for clients, and it does not belong in a free reference page.

Where public sources disagree, I say so rather than picking a winner. Where a figure has not been published, the field says so rather than carrying an estimate. An empty field is information too.

Public filings tell you what a company has said. Whether it holds up is a different question, and the one I get hired to answer.

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