Round magnet

The most critical factor is the material type, typically Neodymium (NdFeB), Ferrite (Ceramic), or Alnico. For high-performance applications, NdFeB grades like N35 to N52 are standard, where higher numbers indicate stronger magnetic pull. You must also specify the Maximum Operating Temperature, as standard Neodymium magnets lose magnetism above 80°C (176°F) unless high-coercivity grades (e.g., SH, UH, or EH series) are selected.

Since Neodymium is highly prone to oxidation, a robust coating is essential. The industry standard is Ni-Cu-Ni (Nickel-Copper-Nickel) plating, which offers excellent corrosion resistance. For outdoor or medical use, consider Epoxy coating or Zinc plating. Ensure the supplier provides a Salt Spray Test report (typically 24 to 48 hours) to verify the coating's durability in humid environments.

B2B buyers should demand a tolerance of ±0.05mm for precision applications. You must also clarify the Magnetization Direction: most round magnets are Axially Magnetized (poles on the flat surfaces), but some applications require Diametrical Magnetization (poles on the curved sides). Incorrect orientation will render the product unusable for your specific assembly.

Magnets must comply with RoHS (Restriction of Hazardous Substances) and REACH regulations to ensure they are free from toxic elements. If the magnets are intended for toys or consumer electronics, they must meet EN71 or ASTM F963 standards to prevent ingestion hazards. Always request Material Safety Data Sheets (MSDS) from the manufacturer.

Magnets are classified as Class 9 Dangerous Goods in air transport if their magnetic field strength exceeds specific limits. You must ensure the supplier uses Magnetic Shielding Packaging (iron sheets and foam) to ensure the external field is below 0.00525 gauss at 4.6 meters. A Magnetic Inspection Report from a certified body (like DGM) is mandatory for air freight clearance.

Utilize secure payment methods and prioritize suppliers on Made-in-China.com who have undergone Audited Supplier verification. Conduct a Pre-shipment Inspection (PSI) to verify the Gaussian value (magnetic strength) using a Tesla meter, as visual inspections cannot confirm magnetic performance. This prevents the risk of receiving 'weak' magnets that do not meet technical specs.

Magnet prices are highly sensitive to the market price of Rare Earth elements (like Neodymium and Dysprosium). Negotiate based on a formula-based pricing model linked to raw material indices. For bulk orders, aim for a 10-15% discount by increasing the volume to meet the supplier's Minimum Order Quantity (MOQ) for a single production run, which reduces setup waste.

Ensure the HS Code (typically 8505.11) is correctly declared on the Commercial Invoice. Be aware of Anti-dumping duties that some regions (like the EU or USA) may impose on specific magnetic products from China. Providing a clear Certificate of Origin and detailed technical data sheets will help expedite the customs process and avoid unnecessary seizures.