Injection-Moulded Plastic Magnets: Properties, Complex Geometries and Applications

Application - 23 Oct , 2026

Injection-moulded plastic magnets combine low weight, dimensional accuracy and magnetic performance, providing efficient solutions for complex industrial components.
To assess the materials, geometries and feasibility of your project, contact the CIBAS team.

Permanent magnets such as sintered ferrite and Neodymium-Iron-Boron have traditionally been associated with rigid, brittle and heavy materials that are difficult to machine without costly post-sintering grinding. Injection-moulded magnets break with these limitations by combining the magnetic properties of filler powders with the outstanding forming capabilities of engineering polymers. For a complete overview of the available materials and processes, see our guide to bonded magnets.

What Are Injection-Moulded Plastic Magnets?

Injection-moulded magnets are composite materials made from two fundamental elements:

The polymer matrix (binder): Usually an engineering thermoplastic such as polyamide (PA6 or PA12) or polyphenylene sulphide (PPS).
The magnetic filler: Permanent magnetic powders made from ferrite, rare-earth materials such as Neodymium-Iron-Boron (NdFeB), or a hybrid combination of the two.

The manufacturing process closely follows conventional plastic injection moulding. The polymer and magnetic-powder mixture is melted inside the moulding machine barrel and injected under high pressure into a metal mould. During injection or cooling, an external magnetic field may be applied to the mould to align the magnetic particles, producing an anisotropic magnet. Without this field, the process produces an isotropic magnet.

Physical and Magnetic Properties of Bonded Magnets

To fully understand the value of these materials, it is necessary to consider the balance between magnetic performance and mechanical properties.

Density and Composition

Because the plastic binder occupies part of the component’s volume—generally between 20% and 40%—the energy density of an injection-moulded magnet is lower than that of a pure sintered magnet. However, the binder provides unique mechanical characteristics:

Resistance to brittle failure: Unlike sintered magnets, which tend to chip or break easily under stress, plastic magnets are resilient and non-brittle.
Electrical insulation: The plastic matrix dramatically reduces eddy currents within the magnet, providing a crucial advantage in high-frequency applications.
Corrosion resistance: The polymer encapsulates and protects the magnetic particles, often eliminating the need for costly surface treatments such as nickel plating or epoxy coating.

Thermal Resistance

The choice of polymer determines the component’s maximum operating temperature:

PA12 (Polyamide 12): Excellent dimensional stability, low water absorption and a maximum operating temperature of approximately 100–120°C.
PA6 (Polyamide 6): Good mechanical properties and operating temperatures up to 140–150°C, but greater sensitivity to moisture.
PPS (Polyphenylene Sulphide): Excellent chemical and thermal resistance, ideal for under-the-bonnet automotive applications, with operating temperatures up to 180–200°C.

The Main Advantage: Complex Geometries and Co-Moulding

The key strength of plastic magnets lies in their design freedom. Designers of electromechanical components are no longer limited to simple shapes such as blocks, cylinders or conventional rings.

A sintered magnet almost always requires grinding with diamond tools to achieve very tight tolerances, increasing costs and waste. Injection moulding delivers the dimensional tolerances typical of plastic components directly from the mould.

Integration of Mechanical Functions

Injection moulding makes it possible to incorporate functional features into a single magnetic component, including:

Gears and toothed wheels
Drive shafts and pins
Bearing seats
Snap-fit clips
Threads and slots

Overmoulding and Insert Moulding

The overmoulding of inserts is a particularly efficient application. A metal shaft or laminated magnetic rotor can be positioned inside the mould, and the plastic magnet can then be injected around it. This eliminates subsequent rotor assembly, bonding and dynamic-balancing operations, significantly reducing the production chain and overall manufacturing costs.

Flexible Multipole Magnetisation

When an anisotropic magnet is moulded, magnetisation channels integrated into the mould can orient the magnetic domains in configurations that cannot be reproduced in a conventional magnet. This makes it possible to create:

Rings with dozens of alternating north and south poles on the internal or external surface.
Skewed magnetisation patterns that reduce cogging torque in electric motors.
Integrated Halbach configurations that concentrate the magnetic flux on only one side of the component.

Industrial Applications of Injection-Moulded Magnets

Their unique combination of magnetic properties and geometric flexibility makes these materials suitable for high-technology markets and high-volume production.

Automotive and E-Mobility

In the automotive industry, reducing component weight and ensuring long-term reliability are essential requirements. Plastic magnets are used in:

Position and speed sensors: ABS sensors, steering-angle sensors, crankshaft-position sensors and transmission sensors.
Small electric motors and actuators: Motors for electric windows, seat adjustment, windscreen wipers and electric coolant pumps, where PPS magnets withstand direct contact with coolant without corroding.
EPS (Electric Power Steering): Electric power-steering systems that require extremely accurate torque sensors.

Home Appliances and White Goods

Inverter motors used in household appliances make extensive use of plastic-magnet rotors:

Drain and circulation pumps for washing machines and dishwashers.
Fans and compressors for air conditioners and refrigerators. In these applications, low operating noise—enabled by continuous and accurate multipole magnetisation—is a key selection factor.

Automation, Robotics and Sensors

Accurate feedback is essential in industrial robotics and automation equipment:

Rotary magnetic encoders: Injection-moulded multipole rings provide extremely accurate pulses to Hall-effect sensors, making it possible to track the angular position of robotic joints.
Flow meters and utility meters: Injection-moulded impellers combine the functions of a hydraulic blade and a signal-transmission magnet.

Injection-moulded plastic magnets represent the ideal meeting point between polymer-material engineering and permanent-magnet physics. They improve overall efficiency wherever low weight, component integration, complex shapes and the elimination of assembly operations are required.

Do you have a project that requires customised magnetic components? Our team can assess its technical feasibility, optimise the geometry and identify the ideal polymer. Contact us.