Understanding NdFeB Grades: N35 to N55

Every NdFeB grade follows a simple naming convention: a letter prefix (N for standard), a number (BH Max in MGOe), and an optional temperature suffix.

• •N = Standard (Sintered NdFeB)
• •Number = Nominal BH Max (e.g., N52 = 52 MGOe)
• •No suffix = 80°C max operating temperature
• •M = 100°C, H = 120°C, SH = 150°C, UH = 180°C, EH = 200°C, AH = 220°C

N55 is the strongest grade available, but it comes with lower coercivity, higher cost, and more brittleness. Most applications are perfectly served by N42 or N45 grades. Over-specifying wastes money without meaningful performance improvement.

• •N35–N40: Cost-effective, good for general-purpose applications
• •N42–N48: Sweet spot — best performance-to-cost ratio for motors and sensors
• •N50–N55: Ultra-high performance, use only when every gram matters

The temperature suffix is arguably more important than the number. Under-specifying the temperature grade causes irreversible demagnetization in the field — the most common cause of magnet failures we see.

• •Always add a safety margin: if your max temp is 100°C, specify SH (150°C) grade
• •Consider the Permeance Coefficient: thin magnets with large air gaps are more susceptible to demagnetization at temperature
• •GBD-processed magnets offer high-temp grades (SH, UH, EH) at near-standard cost — ask us about this option

Key parameters to check on any NdFeB datasheet: Br (remanence), Hcj (intrinsic coercivity), BH Max (energy product), and the demagnetization curves at various temperatures. The curves tell the full story — the numbers are just summary statistics.