Precise control of the dimensions and tolerances of NdFeB (neodymium-iron-boron) magnets is the key to meeting manufacturing requirements, ensuring product yield, and controlling overall costs.
Dimension Range of NdFeB Magnets
Minimum size: 0.5mm × 0.5mm × 0.5mm.
Maximum size: Conventional products can reach 200mm × 200mm × 50mm (e.g., magnets for large motors), while special custom products can be even larger.
Tolerance Range of NdFeB Magnets
| Round / Cylindrical / Disc Magnets
Standard tolerance: ±0.05mm (the most common, applicable to diameter and thickness, striking a good balance between precision and cost).
Strict tolerance: ±0.03mm or tighter (suitable for high-precision magnetic products such as instruments, meters, and testing equipment; some precision requirements can reach ±0.002mm).
| Square / Block Magnets
Standard tolerance: ±0.1mm for length/width, ±0.05mm for thickness.
Strict tolerance: ±0.05mm for length/width, ±0.03mm for thickness.
Factors Affecting the Dimensions and Tolerances of NdFeB Magnets
| Shape and size: Standard shapes (e.g., blocks, discs) are relatively easy to control in size, whereas complex shapes (e.g., arc/segmented, fan shapes) are harder to machine and have more dimensional restrictions. Moreover, the larger the size (e.g., ultra-large magnets over 100mm), the more difficult it is to control dimensions and tolerances during machining.
| Machining process: Slicing/grinding is limited by the machining size — for example, when cutting internal holes — which restricts the minimum machinable size; in such cases, wire cutting (EDM) is required. Wire cutting is suitable for large or complex shapes but has low machining efficiency. Similarly, if the magnet requires drilling, the drilling operation is limited by the drill bit size and the hole-sleeving process.
| Magnet grade: Higher-grade NdFeB materials, such as N52, are hard and brittle, making them prone to micro-cracks or edge chipping during machining. They demand stricter machining parameters, which in turn affects dimensional accuracy.
| Equipment precision: The precision, stability, and degree of automation of the equipment directly determine the ability to control dimensions and tolerances. The more precise the equipment, the more accurate the control of dimensions and tolerances.
Magnets Manufacturer
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