Speaker magnet

The three primary materials are Ferrite (Ceramic), Neodymium (NdFeB), and Alnico. Ferrite is the most cost-effective and resistant to corrosion, ideal for mass-market speakers. Neodymium offers the highest magnetic energy product (BHmax), allowing for powerful yet lightweight and compact designs, though it is sensitive to high temperatures. Alnico provides excellent temperature stability and a classic 'warm' sound profile, often preferred in high-end vintage-style audio equipment.

Buyers must confirm the Remanence (Br), Coercivity (Hcb/Hcj), and Maximum Energy Product (BHmax). For high-performance speakers, ensure the magnet has high magnetic flux density to improve sensitivity and transient response. Additionally, check the dimensional tolerances (typically ±0.05mm to ±0.1mm) to ensure a perfect fit within the voice coil gap, which is critical for preventing distortion.

For Neodymium magnets, Nickel-Copper-Nickel (NiCuNi) plating is the industry standard to prevent oxidation. In high-humidity environments, Epoxy coating is recommended for superior corrosion resistance. Ensure the products pass a 24 to 48-hour Salt Spray Test and comply with RoHS and REACH directives to meet international environmental and safety regulations.

Request information on the magnetization direction (Axial, Radial, or Multi-pole). For automated pick-and-place systems, consistency in magnetic strength uniformity across a batch is vital. Suppliers should provide CPK (Process Capability Index) reports to prove that their manufacturing process maintains tight control over magnetic properties and physical dimensions.

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) and a Non-Magnetic Inspection Report from a recognized authority like DGM. For sea freight, ensure the pallets are properly fumigated and the magnets are vacuum-sealed to prevent moisture ingress during long transit times.

Neodymium prices fluctuate based on rare earth market trends. To manage this, consider long-term framework agreements with price adjustment clauses or hedging strategies. When sourcing via Made-in-China.com, prioritize Audited Suppliers who have stable raw material supply chains to avoid sudden lead-time delays or price hikes.

Never release the final balance without a Pre-Shipment Inspection (PSI). Use a third-party agency to perform a Gaussian test to verify magnetic field strength and a drop test to check for brittleness/cracking. Ensure the inspector verifies the quantity and magnetization orientation against the Proforma Invoice (PI) to avoid receiving unusable stock.

Speaker magnets often require custom molds. Negotiate for a sample fee rebate where the cost of the prototype is deducted from the first mass-production order. Clearly define the Acceptable Quality Level (AQL) in the contract, specifically for surface defects like chips or cracks, which are common in brittle magnetic materials but can impact speaker performance.