Bonded NdFeB Magnet

Overview

Product Specifications

Bonded NdFeB magnets are available in various forms: injection-molded (complex 3D shapes, thin walls down to 0.5mm), compression-molded (higher magnetic properties, simpler shapes), and extruded (long rods/tubes). Typical magnetic specifications include remanence (Br: 0.6-1.1 T), coercivity (Hcj: 600-1600 kA/m), maximum energy product ((BH)max: 6-18 MGOe), and working temperature (-40°C to 150°C depending on binder). Physical specifications include density (5.0-6.1 g/cm³), hardness (Shore D 70-85), and tolerance (±0.05mm for injection molding).

Product Grades

Grades are classified by magnetic performance and temperature resistance. Common grades include: QP-10/5 (low cost, general purpose), QP-15/7 (medium performance), QP-20/9 (high performance), and HT grades (heat-resistant, e.g., QP-18/120 for 120°C operation). Some manufacturers use proprietary grading systems indicating (BH)max and maximum operating temperature, such as BMF-12H (12 MGOe, 120°C). Isotropic grades (most common) can be multi-pole magnetized, while anisotropic grades (higher properties) require orientation during molding.

Coatings

Bonded NdFeB has inherent corrosion resistance due to polymer binders encapsulating magnetic particles, reducing the need for additional coatings. However, for harsh environments, optional surface treatments include: Epoxy painting (improved chemical resistance), Nickel plating (enhanced durability), and Parylene coating (thin, uniform protection for medical/electronics). The binder itself (e.g., nylon, PPS) often acts as the primary corrosion barrier, with salt spray resistance ranging from 500 to 1000 hours depending on formulation.

Application Scope

Bonded NdFeB magnets are widely used in: Electronics (micro-motors in hard disk drives, printers, camera modules, sensors), Automotive (ABS sensors, fuel injectors, dashboard motors, HVAC systems), Consumer Goods (toys, power tools, magnetic closures, headphones), Medical Devices (miniature pumps, surgical instruments, hearing aids), and Industrial (linear actuators, robotics, encoders, magnetic couplings). Their ability to be molded into complex shapes makes them ideal for miniaturized and integrated components.

Packaging Information

Packaging typically includes: Small components in anti-static plastic trays or blister packs to prevent scratching and electrostatic damage. Bulk quantities in sealed polyethylene bags with desiccants to control moisture. For precision parts, vacuum-sealed packaging with foam inserts to maintain dimensional stability. Labels include grade, magnetization direction, quantity, binder type, and storage conditions ("Store in dry environment, avoid temperatures exceeding 80°C"). Shipping packaging uses cardboard boxes with dividers to prevent movement, and magnetic shielding is rarely required due to lower magnetic flux density compared to sintered NdFeB.

Common Questions

· Magnetization: Can they be multi-pole magnetized? Yes, isotropic bonded NdFeB is ideal for multi-pole magnetization (e.g., ring magnets with 8/12 poles) due to uniform magnetic properties in all directions.

· Temperature Sensitivity: How do they perform at high temperatures? Binder type determines limits: nylon (80-120°C), PPS (150-200°C). Exceeding limits causes binder degradation, not irreversible demagnetization.

· Mechanical Strength: Are they brittle? Less brittle than sintered NdFeB but still require careful handling; injection-molded grades have higher impact resistance than compression-molded.

· Design Flexibility: What shapes are possible? Complex geometries (gears, threads, undercuts) via injection molding, which is not feasible with sintered magnets.

· Cost: Why choose bonded over sintered? Lower tooling costs for high-volume production, elimination of secondary machining, and ability to integrate multiple features reduce overall manufacturing costs.