Bonded NdFeB Ring Magnets

Compression bonded magnets contain 97% magnetic powder with higher remanence and density, ideal for applications requiring strong magnetic force, while shape flexibility is limited. Injection bonded magnets hold 80–90% magnetic powder with slightly weaker magnetism, but support ultra-thin complex shapes and insert molding with high production efficiency. Our engineers will recommend the optimal process according to your power output and structural layout.

There is no hard theoretical limit. Actual maximum poles depend on outer diameter and magnetizer capacity. Larger OD allows more poles; tiny rings under 10mm OD can only achieve 24–32 poles due to narrow pole pitch. We have manufactured rings ranging from 2 poles to 120 poles. Our team will optimize pole quantity matching your motor speed and control precision.

Bonded magnets feature 1–12 MGOe max energy product versus 12–55 MGOe for sintered counterparts. Even with lower intrinsic magnetism, multi-pole radial bonded rings can reach equivalent torque via optimized magnetic circuit design and narrow air gap. For miniature stepper and BLDC motors, bonded rings deliver balanced performance at much lower total cost. We provide free magnetic comparison simulation for both solutions.

Simple circular ring molds cost USD 280–700 with 7–10 days lead time. Complex structures with embedded inserts cost USD 700–2800 with 15–25 days development cycle. Sample fees apply separately based on size and quantity. We offer full mold cost rebate once clients hit agreed annual mass order volume to lower upfront investment.

Yes. Base polymer binders offer basic corrosion resistance, but extra surface coating is recommended for long-term exposure to moisture or chemical gas. Available options include epoxy coating (48–500 hours salt spray resistance), electrophoretic coating, Parylene conformal coating and full nylon overmolding. We suggest epoxy + composite metal coating for underwater or corrosive working conditions.

Max working temperature ranges from 80℃ to 180℃ based on magnetic powder grade. Standard M-series grades support 80–120℃, while high-temperature resistant grades withstand up to 180℃. Permanent demagnetization will occur once exceeding rated temperature. Our engineers select matched powder grades and verify thermal stability based on your actual operating temperature and magnetic circuit layout.

Standard stock bonded rings accept low MOQ starting at 100 pieces. New custom molded items require annual mass order quantity of 5,000–10,000 pieces. For R&D verification, we support small trial batches of 20–50 samples with higher unit price. 3D printed plastic prototypes are available at low cost for assembly dimension validation without magnetic function.

Magnetic consistency is measured by flux and magnetic moment deviation. General industry standard allows ±5% flux deviation, while Fullzen internal control restricts it within ±3%, tightened to ±2% for automotive electronics. Other key indicators include dimensional tolerance, concentricity, verticality, surface defect rate, mechanical strength and thermal stability. Fullzen issues traceable full inspection reports including dimension, flux and appearance test data for every shipment.