Product Overview
Shallow pot magnets are compact permanent magnet assemblies in which a permanent magnet core is fitted into a shallow steel cup or housing. The metal housing protects the brittle magnet material and provides a defined mechanical mounting structure while directing magnetic flux toward the exposed working face.
They are specified when a project requires a low-profile magnetic mounting point rather than a bare permanent magnet. For industrial purchasing and engineering design, the complete assembly-including pot geometry, magnet dimensions, mounting method, working surface, air gap, and operating temperature-determines actual holding performance.
Key Technical Specifications for Selection
|
Specification |
Engineering Consideration |
|
Magnet Material |
NdFeB, ferrite, SmCo, or AlNiCo based on energy and environmental needs. |
|
Magnet Grade |
Selected according to required magnetic output and operating conditions. |
|
Outer Diameter (OD) |
Determines available mounting space and overall footprint. |
|
Overall Height |
Critical for low-profile and restricted-depth installations. |
|
Pot Depth |
Defines the internal space allocated for the magnet and housing wall. |
|
Mounting Type |
Plain body, threaded stud, internal thread, or countersunk hole. |
|
Pull Force |
Must be evaluated under defined test conditions (plate thickness and air gap). |
|
Magnetization |
Axial or application-specific multi-pole configuration. |
|
Surface Finish |
Nickel, zinc, epoxy, or passivated stainless steel for corrosion control. |
|
Operating Temperature |
Must match the metallurgical limits of the magnet material. |
|
Dimensional Tolerance |
Essential for mechanical fit, alignment, and repeatable assembly. |
Magnetic Circuit and Working Principle
The steel cup functions as an active component of the magnetic circuit, not merely a protective shell:
Flux Concentration: The steel housing channels magnetic flux lines toward the working face, significantly increasing holding force on flat steel plates compared to an unshielded magnet of identical volume.
Shielding Effect: The magnetic field is largely contained within the steel pot on the sides and back, preventing unwanted attraction to surrounding metal components.
Geometrical Optimization: Modifying pot diameter, wall thickness, or depth alters the magnetic field distribution. Replacing a shallow pot magnet with a bare disc magnet of identical dimensions will not yield equivalent mounting performance.
Material Performance Profiles
NdFeB Shallow Pot Assemblies
Neodymium-iron-boron is selected when a compact assembly requires maximum magnetic force. They are deployed where installation space is strictly limited but high holding forces are mandatory. Standard grades such as N35, N42, or N52 must be evaluated alongside the complete housing geometry rather than as isolated values.
Ferrite Shallow Pot Assemblies
Ceramic (ferrite) options suit applications where extreme holding strength is not required. Their lower material cost and inherent corrosion resistance make them practical for cost-sensitive fixtures, large-volume production assemblies, and environments where moisture resistance is prioritized over high energy product.
SmCo and AlNiCo Options
Samarium-cobalt and AlNiCo serve specialized thermal requirements. SmCo remains stable at elevated temperatures where NdFeB experiences irreversible magnetic loss. AlNiCo offers stable thermal performance with distinct magnetic and mechanical characteristics, suiting specific instrumentation and high-temperature positioning tasks.
Standard Mechanical Mounting Configurations
Assemblies can be supplied with various mechanical interfaces to suit integration requirements:
Plain Cylindrical Bodies
Secured via press-fit, clamping, or adhesive bonding.
Countersunk Holes
Accommodates flat-head screws for flush mounting surfaces.
Threaded Studs or Bosses
Allows direct screw-in attachment to panels or equipment.
Internal Threaded Holes
Accepts bolts or threaded rods from the mounting side.
Custom Interfaces
Tailored pin configurations, step diameters, or non-standard threads.
Packaging, Magnetic Shielding, and Compliance
For industrial export and bulk delivery, pot magnets require professional handling:
Magnetic Shielding: Steel keepers or spatial air-gap padding are used during transit to contain stray magnetic fields, ensuring compliance with international air and ocean freight safety standards (IATA regulations).
Corrosion Protection: Components are treated with anti-rust oil or individually sealed in moisture-barrier bags to prevent oxidation during international shipping and extended warehouse storage.
Batch Traceability: Cartons are labeled with material grade, batch numbers, and production dates to support strict quality control requirements.
Custom OEM Engineering Support
While standard dimensions fit many applications, custom projects often require tailored parameters. Engineering modifications include:
Non-standard outer diameters and restricted overall heights
Specific thread sizes, pitch, or custom mounting geometry
Specialized coatings for chemical, marine, or food-grade environments
Tailored magnetic pull force to match specific operating loads
FAQ
Q: What causes a pot magnet to lose holding force in actual operation?
A: Actual holding performance drops when the mating steel plate is too thin to absorb the magnetic flux, when an air gap exists due to surface roughness, paint, or debris, or when operating temperatures exceed the thermal threshold of the specific magnet material.
Q: Can shallow pot magnets be used outdoors or in humid environments?
A: Yes, provided the correct material and surface finish are specified. Standard NdFeB assemblies require protective coatings such as nickel-copper-nickel or epoxy to prevent oxidation, while stainless steel housings or ferrite alternatives can be selected for corrosive environments.
Q: What is the difference between direct pull-off force and shear force?
A: Pull-off force measures the perpendicular load required to detach the magnet from a standard steel plate. Shear force measures the resistance to sliding parallel along the mounting surface. Shear capacity is typically a fraction of the direct pull force and depends heavily on friction and clamping design.
Q: How do you prevent demagnetization at elevated temperatures?
A: Demagnetization is prevented by selecting the appropriate magnet alloy matching the maximum operating temperature. While standard NdFeB grades lose strength above eighty degrees Celsius, high-temperature grades like SmCo or specialized high-coercivity NdFeB variants maintain magnetic stability under elevated thermal conditions.
Q: What file formats are accepted for custom OEM drawing reviews?
A: Engineering teams can review standard CAD formats including STEP, IGES, DXF, and PDF drawings. Providing clear dimensional tolerances, thread specifications, and operating load requirements ensures rapid evaluation and quotation.
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