You qualify a magnet supplier in China the same way you qualify any process vendor: check who they are, what they can actually make, and whether it can legally reach you. Seven checks, in that order, because each one is cheaper than the one after it.
What does it take to qualify a magnet supplier in China?
| Check | Ask for this | Red flag |
|---|---|---|
| 1. Manufacturer | Business licence, and a live unedited video of a named workshop | Photo folder only |
| 2. Documents | Certificate number, dates, and the scope line | Scope says trade, not production |
| 3. Magnetics | Br, Hcj, BHmax and the demag curve at your temperature | Grade name repeated instead of data |
| 4. Drawing | Your drawing back, marked with what they can't hold | A price by lunchtime, no questions |
| 5. Samples | Same tooling as production, acceptance criteria in writing | "Samples are always fine" |
| 6. Export | Licence position for your country and end use, in writing | A guaranteed number of days |
| 7. Commercial | Tooling ownership, Incoterms, failure clause | Only the unit price is firm |
Read the right-hand column first. Every red flag there can be raised by email, before anyone quotes anything. Print the table and fill the middle column as they answer.
Is it a factory or a trading company?
Almost everyone opens with "are you ISO 9001 certified?" The certificate proves a management system exists. It proves nothing about whether the company owns a sintering furnace.
The document that answers the question is the business licence, and specifically its business scope line. A manufacturer's scope names production of magnetic materials. A trader's names wholesale or import and export, and nothing about making anything. Certificate numbers are searchable in the issuing body's own registry[9][10], so a scope line that says trade rather than production is checkable in two minutes.
A trading company isn't automatically disqualified. Some run tight quality control and carry real engineering knowledge. But you need to know which one you're talking to, because it changes who you escalate to when a lot fails, and how many margins are stacked into your price.
Four questions sort it out faster than any certificate, and none of them need you to be a magnet engineer:
- How many sintering furnaces do you run, and what's the chamber loading?
- Is plating in-house or subcontracted, and which stack do you run most?
- What's your press tonnage range, and is the field alignment axial or transverse on this part?
- Can you walk the sintering line on video right now, unedited?
The last one sorts people fastest. Anyone can send a photo folder. A live walk through a named workshop, with someone answering while the camera moves, is hard to fake.
We started in 1992 as a rare-earth sourcing house and only began our own production in 1994, so we've sat on both sides of this question. It's why we'd rather you ask it early and get a straight answer either way than find out at the first failed lot.
How do you read a magnetic test report?
The grade is on the PO, on the packing list, on the label. It still tells you almost nothing about whether the part survives your duty cycle.
| Instrument | What it measures | What it tells you |
|---|---|---|
| B-H tracer | Material properties on a test slug | Whether the alloy is the grade it claims to be |
| Helmholtz coil | Total magnetic moment of a finished part | Whether piece 5,000 matches piece 1 |
You want both, at different stages. A supplier who confuses the two is telling you something about their lab.
Why Hcj is the number that matters
Remanence tells you how strong the magnet is at room temperature. Intrinsic coercivity, Hcj, tells you how much heat and opposing field it survives before that strength stops coming back[1]. A part that measures beautifully on the bench and fades in service failed on Hcj, not on Br. That's why the report matters more than the grade stamp: two suppliers can both ship "N45SH" and only one of them has the curve to show at 120 °C.
Ask which standard the declared values sit against: IEC 60404-8-1:2023 specifies minimum values for the principal magnetic properties of permanent magnet materials, plus dimensional tolerances[2]. Naming it separates a lab from a spreadsheet.
Ask for the curve at your operating point
The working point depends on geometry and the circuit around it. A thin disc in open air and the same disc closed by a steel yoke behave differently at the same temperature[3], so a free-space curve can look fine and still mislead you. Send the assembly context with the request.
If your part runs hot, ask how they raise coercivity. Adding dysprosium is the blunt route and it costs both money and remanence. Grain boundary diffusion puts the heavy rare earth at the grain boundaries where it does the work, so Hcj goes up using less of it[4]. Grade-by-grade numbers are on our NdFeB magnet grade chart.
Can they hold your drawing?
Most drawings we see come back with a price and nothing else. The useful reply is the opposite: your own drawing, returned with two dimensions flagged and a note about the chamfer. So send it before the RFQ and ask them to mark what they can't hold. Here's what to pin down while they have it open:
| Spec | What to ask | What we run |
|---|---|---|
| Tolerance | Which faces are ground, which are as-pressed | ±0.05 mm on ground dimensions |
| Grade | Standard or high-temperature family | N35–N55 · N35H–N33AH |
| Coating | Stack by name, thickness range, corrosion test in hours | NiCuNi · Ni · Zn · epoxy · Parylene |
| Edge condition | Accept or reject criteria for chips and cracks | Agreed per drawing |
| Magnetisation | Shipped magnetised or not, and what that does to freight | Either, decided at quotation |
| Traceability | Whether material can be traced back per batch | Full material traceability per batch |
The coating row is the one people skim. "Nickel plated" isn't a specification: ask for the stack and the salt spray or PCT hours it's qualified to. Restricted-substance declarations belong against the coated part, not the alloy alone, checked against the current ECHA candidate list[5]. And a supplier who quotes tighter than ±0.05 mm without asking which feature needs it is selling you a number, not a process. Custom geometry runs through the same route as our custom neodymium magnets.
The sample question people forget
Prototype samples are often cut or ground from a sintered block. Production parts are pressed to near shape in a die under an aligning field. Same grade name, different edges, different alignment quality.
Ask in writing whether your samples come off production tooling, then agree acceptance criteria before anything ships: which dimensions, measured how, what flux window in your fixture, and what happens to a lot that falls outside.
Can they legally ship to your country?
Since 2025, some NdFeB shipments out of China need an export licence, so settle this before the PO rather than after. Licensing is handled case by case, and with complete documentation it generally runs around two to four weeks[6].
Be careful with anyone who promises a fixed number of days. The timeline depends on your end use, your destination and the paperwork you provide, none of which the factory controls. Expect to supply an end-user statement and a description of the end use, sometimes the importer's details[7].
Two questions sort this out: have you filed successfully for my country before, and what do you need from me to start. A supplier who answers both has done it. One who says "no problem, we always ship" hasn't read the rules. For why the supply base sits in China at all, the USGS mineral commodity summaries are the neutral source[8].
Which red flags should end the conversation?
- A quote with no question about your operating temperature or assembly. Nobody selects a grade without knowing the working point.
- A grade number above N55. Standard sintered NdFeB tops out there, so anything higher is a relabelled part or a fabrication.
- A price far below everyone else on the shortlist. That gap is a different grade, a thinner coating or a different plating stack. Ask which.
The decision in one line
Run checks 1, 2 and 6 before you spend any engineering time. They're free and they eliminate the most suppliers. Spend real effort on 3, 4 and 5 only with whoever is left.
Business scope, certificate registry lookup, export licence position. All three are email questions, and a weak answer to any of them ends it.
Test report at your temperature, marked-up drawing, samples off production tooling. These cost weeks, so run them only on a shortlist that already passed the cheap checks.
The sequence from marked-up drawing to first delivery is in our custom magnet ordering process[11]. If you're still deciding what to buy rather than who from, start with the neodymium magnet buyer's guide[12].
Frequently asked questions
How can I tell if a Chinese magnet supplier is a factory or a trading company?
Read the business scope on the licence: a manufacturer's names production of magnetic materials, a trader's names wholesale or import and export. Then test it with process questions about sintering furnaces, press tonnage and whether plating is in-house, and ask for an unedited live video walk of a named workshop. A trader can send photos and certificates but cannot walk you through a line it does not own.
Which certifications should a neodymium magnet supplier hold?
ISO 9001:2015 as the baseline and IATF 16949 for anything going into a vehicle, plus RoHS and REACH declarations against the coated part. Check the number in the issuing body's registry and read the scope line: a valid certificate for the wrong scope is the most common document problem. Mainrich holds ISO 9001:2015, IATF 16949, RoHS, REACH, CE and CCC.
What dimensional tolerance can a magnet factory realistically hold?
Our standard is ±0.05 mm on ground dimensions. As-pressed faces don't carry the same tolerance, so specify which features are critical instead of applying one figure to the whole part. If a supplier offers something tighter without asking which dimension needs it, ask them to explain the measurement method first.
Do I need an export licence to import neodymium magnets from China?
Some NdFeB shipments have required a Chinese export licence since 2025, depending on the material, the end use and the destination. Applications are handled case by case and, with complete documentation, generally take around two to four weeks. Treat a promised fixed number of days as a warning sign, and raise the topic before the PO because you will need to supply an end-user statement.
Is there a minimum order quantity, and how fast is a quote?
There is no MOQ on custom orders at Mainrich, and we quote in 24 hours from a drawing or a clear specification. Tooling cost and unit price both move with quantity, so a prototype run prices differently from a production release, but a low quantity does not block the order. Ask any supplier to state sample and production lead times separately rather than giving you one number.
Get a quote with the data behind it
Send your drawing with the operating temperature and quantity. We quote in 24 hours, with a grade recommendation for your thermal case and the demagnetisation curve behind it.
Get a quoteSince 1992 · No MOQ · We quote in 24 hours
References
- Intrinsic coercivity (Hcj) · Mainrich magnet glossary
- IEC 60404-8-1:2023, Magnetic materials, Part 8-1: Specifications for individual materials · International Electrotechnical Commission
- NdFeB magnet grade chart and selector · Mainrich Magnets
- Grain boundary diffusion (GBD) · Mainrich Magnets
- Candidate list of substances of very high concern for authorisation · European Chemicals Agency
- China's 2025 dual-use export controls: what is in scope · Mainrich Magnets
- Rare earth magnet export compliance: documents buyers must supply · Mainrich Magnets
- Rare earths statistics and information · U.S. Geological Survey
- ISO 9001:2015, Quality management systems, Requirements · International Organization for Standardization
- IATF 16949:2016, Automotive quality management system standard · IATF Global Oversight
- Custom magnet ordering process · Mainrich Magnets
- The neodymium magnet buyer's guide · Mainrich Magnets
