Magnets

When selecting magnets, the most critical factor is the Magnetic Grade (e.g., N35, N52 for Neodymium), which determines the Maximum Energy Product (BHmax). You must also specify the Remanence (Br) and Coercivity (Hcb/Hcj) to ensure the magnet performs under specific loads. For high-temperature environments, verify the Maximum Operating Temperature; for instance, standard Neodymium magnets lose magnetism above 80°C, whereas Samarium Cobalt (SmCo) or high-grade SH/UH/EH Neodymium can withstand up to 200°C+.

Raw magnet material, especially NdFeB, is highly prone to oxidation. You must specify the Coating/Plating type, such as Ni-Cu-Ni (Nickel), Zinc, Epoxy, or Gold. For outdoor or medical use, Epoxy coating provides superior salt spray resistance. Always request a Salt Spray Test Report (typically 24-48 hours) to validate the coating quality and prevent long-term corrosion in your end product.

Magnets must comply with RoHS (Restriction of Hazardous Substances) and REACH regulations to ensure they are free from toxic elements. If the magnets are used in toys, they must meet EN71 or ASTM F963 standards regarding magnetic flux index to prevent ingestion hazards. For electronics, ensure the supplier provides MSDS (Material Safety Data Sheet) for safe handling and transport.

Do not rely solely on theoretical values. Request a Hysteresis Graph (Demagnetization Curve) from the supplier's testing lab. For bulk orders, implement a Pull Force Test using a digital tension meter and a Gaussian Meter to check surface magnetism. Ensure the Dimensional Tolerance is strictly controlled (typically ±0.05mm) to avoid fitment issues in precision assemblies.

Magnets are classified as 'Dangerous Goods' for air freight because they can interfere with aircraft navigation systems. You must ensure the supplier provides Magnetic Shielding Packaging (using iron sheets and foam). An Air Transport Safety Test Report (Magnetism Inspection) is mandatory for air shipments. For sea freight, while less restrictive, proper moisture-proof vacuum packaging is essential to prevent oxidation during long transit times.

The biggest risk is 'Grade Substitution', where a supplier provides N33 instead of N38. To mitigate this, use Made-in-China.com's Secured Trading Services to hold payment until quality is verified. Conduct a Pre-shipment Inspection (PSI) by a third party to test the magnetic flux of random samples from the batch. Always clarify the Incoterms (e.g., FOB vs. DDP) to understand who bears the cost of specialized magnetic clearance.

Magnet prices are heavily influenced by Rare Earth market fluctuations (PrNd metal prices). Negotiate a Price Adjustment Formula based on public market indices to ensure fairness. For long-term contracts, seek Volume-Based Rebates or tiered pricing. Since magnets are heavy, negotiating palletized packaging included in the unit price can save significant costs on labor and damage claims during unloading.

Ensure the supplier holds the necessary Patent Licenses, especially for Sintered NdFeB, to avoid customs seizures related to Section 337 investigations (common in the US market). Verify the HS Code (typically 8505.11) is correctly declared to avoid tariff penalties. For large-scale B2B buyers, sourcing from Audited Suppliers on Made-in-China.com ensures the factory has been physically verified for production capacity and legal compliance.