Injection molded ferrite magnets are magnetic composite materials produced by blending ferrite magnetic powder with polymer resins (e.g., PA6, PA12, PA66, PPS) and forming them via injection molding. The manufacturing process involves key steps such as magnetic powder surface treatment, feedstock compounding/pelletizing, and magnetic field-oriented injection molding. The resulting products exhibit magnetic properties including a remanence of 178.5 mT and a coercivity of 244.4 kA/m, making them suitable for permanent magnet DC motors, variable-frequency AC motors, automated equipment signal sources, and other applications. Industrial production employs 50–160 T fully闭环注塑机 (fully closed-loop injection molding machines) and multi-directional orientation systems. By optimizing the feedstock formulation, core density can be increased to 5.25 g/cm³, with flexural strength exceeding 50 N.

Materials and Process
Injection molded ferrite magnets consist of a magnetic powder system comprising 70%–95% ferrite powder and 5%–30% binder. The ferrite powder is formulated with iron oxide (60%–70%), nickel oxide (10%–20%), copper oxide (2%–10%), and zinc oxide (15%–25%). The binder includes polyformaldehyde (86%–90%), high-density polyethylene (2%–4%), and ethylene-vinyl acetate copolymer (3%–6%). The production process involves three stages:

1. Magnetic Powder Pretreatment: Raw materials are ball-milled, calcined at 800–1000°C, and ball-milled again to achieve a particle size of 0.5–2.0 μm.

2. Feedstock Preparation: Powder and binder are intensively mixed at 120–200°C for 45–120 minutes, then crushed into 3–8 μm particles.

3. Molding: Injection molding is conducted at barrel temperatures of 250–280°C, with a 0.5–2 T orientation field applied to achieve grain alignment.

Primary Applications

• Permanent Magnet Motors: Used as constant magnetic sources in DC motors and variable-frequency AC motors, enhanced by radial multi-pole magnetization for improved magnetic field stability.

• Precision Instruments: Serve as signal sources in instrument motors, offering low remanence, low recoil permeability, high coercivity, and strong resistance to demagnetization.

• Automated Equipment: Replace neodymium magnets in magnetic locking mechanisms, reducing costs by 40% while improving corrosion resistance.

• Packaging Industry: Manufactured magnetic latch systems for packaging boxes, achieving directional magnetic force via 0.5–2 T orientation fields.

Ningbo Buji Magnetic-Electronic Technology Co., Ltd. leverages over two decades of expertise in magnetic materials. Core products include:

1. Injection molded magnets (categorized by primary material: neodymium iron boron/ferrite; by binder: PPS/PA);

2. Bonded pressed neodymium iron boron magnets;

3. Sintered neodymium iron boron magnets;

4. Various magnetic assemblies.
   The company aims to be a professional and reliable supplier of magnets and components, delivering cost-effective solutions for magnetic applications.