Manufacturing Routes
Manufacturing Processes
Primary production methods for permanent magnets, explaining differences in magnetic alignment, dimensional tooling, and volume economics.
Production Routes
How Each Route Is Made and Where It Stops
Each card reads from the route's own record: the material system it is run in, what it does well, the limits to plan for around it and the applications it typically serves.
Hard Ferrite (Ceramic) Magnets
Wet Pressed Ferrite
Ferrite slurry compacted in an orienting field and drained during pressing. The route for parts that need more flux per unit volume than dry pressing.
Key Advantages
- More flux per unit volume than the dry-pressed route in the same envelope, argued from the grade evidence for the part
- Long arcs, rings, blocks and discs, pressed from a slurry that holds an alignment the dry route reaches less of
- Anisotropic alignment set in a strong orienting field while the part is compacted, so the direction is designed into the magnetic circuit
- Multipole and radial-oriented patterns on arcs and rings, confirmed against the forming orientation and the magnetizing fixture
- Pressed close to the drawing, with the finishing allowance agreed from the tolerance callouts
Limitations to Plan For
- Tooling is drawn per part and lands before the first good part, so the route is chosen where the performance or the quantity earns it back
- Cycle time is slower than dry pressing, so unit cost and the time to a first batch stay project figures
- Not every large size, thin section or open structure is pressable; the drawing answers that before tooling is discussed
- Post-machining is a per-part question, planned from the drawing and the tolerance callouts
- A higher Hcj does not follow from the route name; it is argued from the grade and process evidence
- Arc segment designs add bonding or fixing, fixtures and consistency checks on top of pressing
Typical Applications
- DC and BLDC motor arc segments
- Automotive booster motors
- Windshield wiper motors
- Industrial pump rotors
- Power tool motors
- Appliance fan and drain pump motors
Related Products
Hard Ferrite (Ceramic) Magnets
Dry Pressed Ferrite
Dried ferrite powder compacted in a press. Suits simple rings, blocks and discs in repeat production; alignment is lower than wet pressing.
Key Advantages
- Rapid cycles and simple tooling, which hold unit cost down on repeat production of standard parts
- Rings, blocks and discs compacted in one stroke, with no complex drainage tooling to amortise
- A good fit where the design's flux requirement is moderate rather than the constraint
- Isotropic or anisotropic grade, chosen against the flux the part actually needs
- Normally supplied uncoated, so there is no plating step to schedule or pay for
Limitations to Plan For
- Alignment is lower than in wet pressing, so achievable magnetic performance is lower
- Minor density gradients can appear within a part, which matters where flux uniformity across the part is critical
- Not the route where flux per unit volume is the constraint; wet pressed ferrite or another material system takes that part
- Anisotropic grades outperform isotropic ones, so the orientation direction has to be defined with the magnet design
Typical Applications
- Loudspeaker magnet assemblies
- Magnetic separators
- Door latches
- Holding and clamping magnets
- Magnetic chucks and workholding
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Hard Ferrite (Ceramic) Magnets
Injection Molded Ferrite
Ferrite powder in a thermoplastic binder, molded to shape — thin walls and complex geometry in a single step; the polymer matrix lowers flux density.
Key Advantages
- Thin walls and complex geometry are molded in one step, which is why this route is chosen over pressing for a difficult part
- Shafts, bushings and mounting features are molded in with the magnet, taking parts and glue joints out of the assembly
- Tolerance comes from the tool, so dimensions a pressed part would need post-machining to hold can be molded directly
- The polymer matrix absorbs impact, so a thin section is less likely to chip than a sintered ceramic part of the same wall
- The binder encapsulates the ferrite particles, so the part normally needs no coating
- Multipole and radial-oriented patterns on thin rings for motors and sensors, evaluated against the tooling and the magnetizing fixture
Limitations to Plan For
- Polymer matrix lowers the magnetic volume fraction and overall flux density compared with sintered magnets
- Not the route for high-flux motor arcs
- Mold and magnetizing fixture costs are project-specific
- Feasibility depends on shape, magnetization pattern and quantity
- Operating temperature depends on the magnetic grade, binder system and application. Moisture absorption, dimensional change, chemical compatibility and long-term mechanical stability must be evaluated for the selected formulation.
Typical Applications
- Laser printer and photocopier magnetic rollers
- Small DC and BLDC motor rotors, including fan and pump motors
- Multipole sensor rings for commutation and position sensing
- Automotive instrument clusters, actuators and small auxiliary motors
- Smart meter and flow sensor rotors
- Insert-molded assemblies, where the magnet is molded onto a shaft or bushing
- Thin-wall rings in appliances and power tools
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Neodymium (NdFeB) Rare Earth Magnets
Sintered NdFeB
NdFeB strip cast, milled, pressed in a field, sintered and heat treated. Rings, discs, blocks and arcs; the parts are brittle, so handling needs care.
Key Advantages
- The highest energy product of the NdFeB family, so the flux comes from the smallest envelope available
- Above bonded NdFeB and above ferrite, which is why compact high-torque motors end up on this route
- High-coercivity series extend the usable working temperature where the magnetic circuit allows
- Machined to the drawing after sintering, so demanding dimensional and functional requirements are met rather than approximated
- Grade, coating and magnetization are specified together against the operating conditions, not left to a default finish
Limitations to Plan For
- Brittle material: handling, packaging and mechanical support need attention in the design
- Corrosion protection is part of the specification, selected for the environment and the assembly process
- Grade selection has to bring in the actual magnet temperature, the magnetic circuit and the demagnetizing conditions
- Machining is a real cost line, because a sintered blank is ground to the drawing rather than molded to it
- Material price and quotation validity are confirmed in the quotation rather than held as a list price
Typical Applications
- Industrial servo motors
- EV traction motors
- Linear actuators
- High-torque robotic joints
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Neodymium (NdFeB) Rare Earth Magnets
Compression Molded NdFeB
Rapidly quenched NdFeB powder in an epoxy matrix, compression molded into thin-wall rings and arcs. Remanence is below sintered; the gain is in shape.
Key Advantages
- Isotropic material, so the magnetization direction is set after molding and not fixed by the tool
- Multipole and skewed multipole patterns, which is what sensor and encoder duty asks for
- Thin-walled rings and arcs molded close to net shape, with the tolerance set on the drawing
- The epoxy matrix reduces the chipping a brittle sintered part of the same section shows
- Grades from PMC-1 to PMC-13 are published on this page, so the flux level can be checked before a quote
Limitations to Plan For
- Remanence is lower than sintered NdFeB, because the resin dilutes the magnetic volume fraction
- Operating temperature is set per grade — 100–160 °C across the listed range — and confirmed against the application
- Not the route for maximum flux in a very small envelope; sintered NdFeB remains the answer there
- Tooling and powder supply are more specialised than on the ferrite routes
Typical Applications
- Spindle motors for optical drives
- Office automation equipment
- Stepping motors
- Sensor and encoder rings
- Small BLDC fan motors
Related Products
Neodymium (NdFeB) Rare Earth Magnets
Injection Molded NdFeB
NdFeB powder in a thermoplastic binder. Suits sensor rotors and small actuators; output is below sintered NdFeB and the binder sets the heat limit.
Key Advantages
- Magnetic powder and binder are one compound, so a complex geometry is molded rather than pressed and machined
- Bores, bosses, wall sections and the pole-carrying face are formed by the mold, which takes assembly steps out of the part
- A shaft or insert can be molded in where the design allows, with insert compatibility evaluated per project
- Multipole patterns on sensor rotors and small actuators, evaluated against the geometry and the magnetizing fixture
- Post-machining is limited to what the drawing actually calls for
- Reference grade data for NBI-4 to NBI-8 is published on this page, so a design can be checked before a quote
Limitations to Plan For
- Magnetic output is generally lower than sintered NdFeB, and follows the powder loading and the formulation
- Usable temperature is set by the powder, the binder system and the magnetic circuit, not by the route name
- Mold material and wear resistance have to be selected for the compound, which is a tooling decision
- Corrosion exposure and binder compatibility are reviewed before the specification is fixed
- Not the route where the flux requirement is set by the envelope; sintered NdFeB takes that part
Typical Applications
- Position sensor rotors
- Micro-actuators
- Contactless automotive throttle sensors
- Sensor rings for motor commutation
- Small fan and pump motor rotors
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Production Route Allocation
Need to Validate Tooling Feasibility for Wet vs. Dry Pressing?
Tooling questions — cavity shrink rates, orientation coils and grinding tolerance — are agreed with the producing factory before steel is cut.