Industrial grade permanent magnet solutions with custom inner diameters and structural configurations
Permanent magnets containing central through-holes, countersunk apertures, or custom counterbores represent a specialized branch of magnetic component engineering. In modern product design, these geometries are crucial because they permit direct mechanical fastening using non-magnetic screws or locating pins. Sintered Neodymium-Iron-Boron (NdFeB) ring and countersunk magnets are widely adopted due to their high magnetic flux output relative to physical footprint.
However, the presence of a hole complicates the mechanical integrity and the internal magnetic circuit. Sintered NdFeB is inherently brittle, acting similarly to structural ceramics. Machining processes such as diamond-wheel drilling, wire-cut EDM, and CNC grinding must be managed under strict coolant flow and feed-rate controls to avoid introducing micro-cracks along the perimeter of the inner diameter (ID).
A through-hole removes magnetic volume, thereby shifting the operating load line (or permeance coefficient, Pc) of the magnet to a lower value. When designing ring magnets or countersunk blocks, engineers must calculate the demagnetizing fields around the aperture to ensure the selected material grade (e.g., N42SH, N45UH) can resist working demagnetization under operating temperature extremes.
Established in 1999, Zhejiang Laysun Magnetics Ltd. has built a reputation as a national high-tech leader in the rare earth permanent magnet sector. Headquartered in Hangzhou, China, our main production infrastructure spans 100,000 square meters in Suining, Sichuan. This geographic layout aligns our operations with Western China's raw material mining clusters, securing stable supply lines and pricing for rare earth metals like Praseodymium-Neodymium (PrNd), Dysprosium (Dy), and Terbium (Tb).
Our production facility processes sintered NdFeB from raw oxide melting to final vacuum sintering, machining, plating, and testing. Supporting an annual capacity of 5,000 metric tons, Laysun delivers reliable magnetic components to major players in the electric vehicle, industrial automation, consumer electronics, and wind generation sectors.
When sourcing China permanent magnets with holes, specifying correct physical dimensions and mechanical constraints is key to manufacturing success. Sintered magnets are finished using grinding rather than standard cutting, requiring defined tolerances:
Through-hole magnets can be axially oriented (poles on flat faces), radially oriented (demanding customized multi-polar pressing molds), or diametrically oriented to suit specific encoder or sensor arrays.
Our NdFeB hole magnets feature complete coating coverage within the internal hole, utilizing NiCuNi, black/grey epoxy, Zn, or chemical vapor deposition (CVD) Parylene to prevent environmental corrosion.
We utilize Dysprosium (Dy) and Terbium (Tb) grain boundary diffusion (GBD) technologies to manufacture high-coercivity grades (such as N52SH or N48UH) while minimizing total heavy rare earth content.
Industrial applications of NdFeB magnets across sectors including transportation, automation, and consumer electronics
For motor design engineers, the mechanical design of permanent magnet rotors has shifted toward complex geometric arrays. Ring magnets with inner locating holes are preferred for high-speed brushless DC (BLDC) motors and automotive Electronic Power Steering (EPS) assemblies. The inner diameter mates directly with the motor shaft, reducing rotational imbalance and simplifying assembly compared to gluing segmented arc magnets.
In voice coil motors (VCM) for optical pick-up drives and camera focusing units, ring magnets provide linear magnetic fields with low hysteresis. Zhejiang Laysun Magnetics works with automation engineers to supply magnet assemblies that meet mechanical tolerances and precise magnetic field distributions, helping to ensure system reliability.
Understanding the supply chain factors behind China's position in rare earth magnet manufacturing is valuable for global procurement teams:
Custom geometries engineered to meet specific industrial and commercial requirements
To serve as a Tier-1 supplier to global industrial markets, Zhejiang Laysun Magnetics maintains a comprehensive quality management system. Our manufacturing process and testing procedures are certified under ISO9001 and ISO14001, providing structural quality control from raw materials to final shipment.
For applications in the oil and gas sector, our engineering team manages product testing in line with API 6D and API 607 specifications. Additionally, we provide CE declaration compliance and material trace certificates upon request. Our testing labs are equipped to perform Salt Spray Testing (SST), Highly Accelerated Life Testing (HAST), and demagnetization curve analysis (using hysteresigraphs) to verify chemical and magnetic properties prior to shipping.
Detailed design and purchasing guidelines for international procurement teams
Industrial components including pot assemblies, magnetic badges, and specialized lifting solutions
Laysun Magnetics