We supply precision 8-Pole Axial Neodymium Rings (Face Multi-Pole). The entire top face of standard ring magnets is North and the bottom is South. But these specialized magnets feature 8 alternating poles (4N / 4S) distributed radially across the flat surface. This “Surface Magnetization” configuration creates a dense, shallow magnetic circuit. These loops are directly across the face of the ring. This geometry is the industry standard for Rotary Encoders, Speed Sensors, and high-efficiency Magnetic Couplings. Their the magnetic field must interact with a sensor or steel plate parallel to the magnet’s face. The Engineering Logic: Why “Surface” Magnetization? Explain the physics. Why do they want this weird pattern? 1. Sensor Resolution (4 Pulses per Rev): The Application: – Rotary speed detection. The Function: – As the ring rotates, a Hall Effect sensor placed near the surface detects 4 distinct North-South cycles per revolution. The Benefit: – This provides 4x the data resolution of a standard 2-pole magnet. – Such feature allows for precise speed and position control in robotics and motor feedback systems. 2. Superior Holding on Thin Steel: The Application: – Magnetic latches on thin sheet metal. The Physics: – Standard magnets shoot their field deep into space. – Multi-pole magnets loop their field tightly between the N and S sectors on the face. The Benefit: – This concentrates 100% of the magnetic energy right at the surface. – And it provides exceptionally strong holding force on thin steel sheets (where standard magnets would “bleed” through and lose grip). Manufacturing & Tooling Pulse Magnetization: – Creating this pattern on Sintered Neodymium requires a specialized High-Voltage Magnetizing Fixture (Coil). Standard Sizes: – We often have existing fixtures for common ODs (e.g., 20mm, 30mm), saving you tooling costs. Custom Sizes: – For unique dimensions, a one-time fixture fee may apply to build the custom coil. Applications Rotary Encoders: Volume knobs, robot joints, and control dials. Brushless DC (BLDC) Motors: Axial flux pancake motors. Magnetic Couplings: Driving a mixer or pump through a flat plastic wall. Smart Accessories: Tablet case attachments (the tight field doesn’t damage internal electronics). Ordering Guide: Critical Data To quote this item, we need to know: 1). Dimensions: OD x ID x Thickness. 2). Sensor Match: Are you using this with a specific Hall Sensor chip? (Knowing the “Operating Gap” helps us verify the strength). 3). Reference Mark: Do you need a physical mark (laser dot or notch) to indicate the “Zero Position” (Start of Pole 1)? 4). Back-Iron: Will this be glued to a steel shaft? (This boosts the performance).