Technomag Inc. manufactures Alnico magnets (cast and sintered) in various sizes and specifications. We meet the highest quality standards set by MMPA (Magnetic Materials Producers Association).
Applications
Alnico magnets are widely used in applications that require high temperature stability, strong magnetic fields, and resistance to demagnetization. They are commonly found in electric motors, generators, sensors, and loudspeakers due to their ability to maintain performance in extreme environments. Their durability makes them suitable for measuring instruments, magnetic clamps, and holding devices, while their consistent magnetic strength at elevated temperatures supports use in aerospace, automotive, and industrial machinery. Additionally, Alnico’s reliability and stability make it valuable in scientific equipment and specialized medical devices.
Key Features
- Material Composition: Alloys of aluminum (Al), nickel (Ni), cobalt (Co), with iron (Fe) as the base, and small amounts of copper (Cu) or titanium (Ti) for property enhancement.
- Manufacturing Methods: Typically produced by casting into sand molds or by powder metallurgy (sintering), followed by heat treatment and magnetic field annealing to optimize magnetic properties.
- Magnetic Strength: Moderate magnetic strength (lower than rare-earth magnets, higher than ferrites) but excellent stability over a wide temperature range.
- Shapes & Complexity: Cast Alnico allows production of large or complex shapes; sintered Alnico offers tighter tolerances but is generally limited to simpler geometries.
- Mechanical Properties: Hard and brittle, prone to chipping or cracking under mechanical or impact stress; requires careful handling and machining.
- Magnetic Orientation: Usually anisotropic (field-oriented during heat treatment for higher performance), though isotropic grades also exist with lower magnetic performance.
Classification
Alnico magnets are typically classified into cast and sintered types, with further sub-grades based on composition and performance:
1. Cast Alnico Magnets
- Process: Produced by casting molten alloy into sand molds, then heat-treated and magnetically oriented.
- Features:
- High magnetic output (stronger than sintered types).
- Can be made in large or complex shapes.
- Slightly lower dimensional accuracy than sintered magnets.
- Grades: Often designated as Alnico 2, 3, 5, 8, 9 (each differing in composition, coercivity, and energy product).
- Alnico 5: Most widely used, offers a good balance of strength and stability.
- Alnico 8 & 9: Higher coercivity, better suited for applications with strong demagnetizing fields.
2. Sintered Alnico Magnets
- Process: Produced by pressing powdered alloy into a mold and sintering in a furnace.
- Features:
- Better dimensional accuracy and uniformity.
- Generally smaller sizes compared to cast Alnico.
- Slightly lower magnetic strength than cast types.
- Grades: Available in similar numbering (e.g., Alnico 5S) but optimized for smaller, precise parts.
3. Isotropic vs. Anisotropic
- Isotropic: Can be magnetized in any direction; lower performance.
- Anisotropic: Magnetized in a preferred orientation during heat treatment; higher performance.