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Neodymium Cup Magnets

High-Clamping Steel-Cased NdFeB Assemblies

Neodymium Cup Magnets (Rare Earth Round Mounting Bases)

CMS Magnetics manufactures commercial and industrial-grade neodymium cup magnets (rare earth pot magnets and round base assemblies) engineered for maximum clamping force in compact footprints. By encasing a high-energy sintered NdFeB permanent magnet inside a precision-machined, triple-plated mild steel cup, the steel walls redirect magnetic flux lines from the rear and sides directly onto the open face. This closed-circuit shunt focuses magnetic saturation to produce up to 5x the direct perpendicular pull force of an unencased magnet, while mechanically protecting the brittle neodymium core from impact, edge chipping, and premature fracture.

Looking for rectangular profiles, high-heat outdoor ferrite, or raw discs? For narrow door jambs and extrusion tracks, view our Neodymium Channel Magnets. For rust-proof, high-temperature (up to 250°C) outdoor mounting, explore Ceramic Cup Magnets. If your assembly requires unshielded raw magnets, browse Neodymium Disc Magnets or pair cups with Steel Magnet Strikers.

Need pre-threaded hanging hardware for workshops or lockers? Browse our selection of heavy duty magnetic hooks built with high-pull neodymium pot bases."

Focused Flux Circuit

Steel cup redirects both poles to a single plane, multiplying contact clamping force up to 300+ lbs.

Full Mechanical Armor

Machined steel sidewalls absorb repetitive direct impacts, preventing brittle NdFeB from cracking.

Multiple Mounting Styles

Available with countersunk center holes, external male studs, and internal female threaded bushings.

Triple Ni-Cu-Ni Plating

Electrolytic nickel-copper-nickel barrier resists atmospheric oxidation and operational wear.

Filter by Mounting Fastener Style: Countersunk Hole Cups Male Threaded Stud Female Threaded Stud Internal Threaded Hole Channel Magnets All Cup & Pot Magnets

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Engineering Guide: Neodymium Cup Magnet Mechanics, Mounting Styles & Saturation

Neodymium cup magnets are engineered to solve the inherent challenges of sintered rare earth material: high mechanical brittleness and omnidirectional flux dispersal. Enclosing a neodymium disc or ring inside a ferromagnetic steel cup transforms an ordinary magnet into an integrated, industrial-grade workholding assembly.

Neodymium Cup Magnet Mounting Configurations

Mounting Configuration	Fastener Interface	Mechanical Installation	Primary Industrial Applications
Countersunk Hole	82° or 90° flat-head machine/wood screw	Fastens flush to non-magnetic walls, beams, or jigs	Concealed cabinet catches, tool hanging, access panels
Male Threaded Stud	External metric or imperial threaded shank	Screws into tapped equipment holes or secures with lock nut	Vehicle roof antennas, emergency beacons, camera mounts
Female Threaded Stud	Raised cylindrical boss with internal threads	Receives threaded bolts, eyelets, or threaded rods	Suspension rigging, conduit routing, hanging signage
Internal Threaded Hole	Flush internally tapped center hole	Threaded fastener bolts through from behind substrate	Blind-mount tooling fixtures, low-profile holding assemblies

The Magnetic Shunt: Why Cased Neodymium Outperforms Raw Magnets

When an uncased neodymium disc magnet is placed against a steel surface, half of its magnetic flux radiates uselessly into the surrounding air from the opposite pole. Enclosing the magnet in a low-carbon steel cup creates a high-efficiency magnetic circuit:

Focused Working Face: The steel cup conducts flux from the rear pole forward to the cup rim. This places both the North and South magnetic poles on the same working plane, concentrating magnetic field lines directly into the contact surface.
Steel Thickness & Saturation: Cup magnets require an adequately thick steel target (typically 1/4" to 1/2" thick clean, low-carbon steel) to absorb the focused flux. Thin sheet metal (such as 18- or 20-gauge steel) quickly saturates magnetically, allowing flux to bleed through and reducing holding strength by 50% or more.
Steep Air Gap Drop-Off: Because the flux path between the central magnet face and the outer steel lip is tightly constrained, neodymium cup magnets achieve extreme clamping power on direct surface contact, but experience a steeper loss of pull strength over air gaps compared to unshielded neodymium blocks or discs.

Holding Physics: Perpendicular Breakaway vs. Vertical Shear Slide

Published holding capacities reflect direct perpendicular pull force (Case 1) tested on flat, clean, ground 1/2-inch structural steel. When mounting cup magnets vertically against gravity:

The Shear Slide Factor (μ): The coefficient of friction between smooth nickel-plated steel surfaces is typically μ ≈ 0.15 – 0.20. As a result, a vertical cup magnet will begin sliding downward under approximately 15% to 20% of its rated perpendicular pull force unless physically supported.
Preventing Slide: To resist vertical shear loads, recess the cup into a shallow pocket, use rubber-coated mounting assemblies, or attach mating pre-drilled Steel Magnet Strikers.
Anti-Twist Linear Mounts: Because round cup magnets can rotate around a single mounting fastener under torque, use rectangular Neodymium Channel Magnets for rigid linear alignment on door jambs and machinery fences.

Frequently Asked Questions

What is the difference between a raw countersunk disc magnet and a countersunk cup magnet?

A raw countersunk disc is an unencased piece of sintered NdFeB that is brittle, vulnerable to cracking under screw torque, and emits flux from both poles. A countersunk cup magnet encloses the magnet inside a steel cup. The steel shell protects the magnet from mechanical shock, absorbs fastener torque, and channels flux forward to generate significantly higher clamping force on contact.

Can neodymium cup magnets be used outdoors or in washdown environments?

Our neodymium cup magnets feature triple-layer nickel-copper-nickel plating on both the steel cup and the magnet core, providing corrosion resistance for indoor and dry industrial use. For permanent outdoor, marine, or washdown applications where moisture can pool inside the cup, choose naturally rust-proof Ceramic Cup Magnets or protect the assembly with silicone sealant.

What is the maximum operating temperature for neodymium cup magnets?

Standard neodymium cup magnets are rated for maximum continuous use up to 80°C (176°F). Operating above this threshold causes irreversible loss of magnetic pull force. For high-heat applications, consider high-temperature NdFeB grades or explore AlNiCo Pot Magnets (up to 500°C) or Ceramic Cup Magnets (up to 250°C).

How do I select between male threaded, female threaded, and countersunk cups?

Select Countersunk Hole Cups for flush screw mounting directly to walls, fixtures, or cabinets. Select Male Threaded Stud Cups when threading into a tapped hole or securing through sheet metal with a hex nut. Select Female Threaded Cups when you need to attach standard bolts, threaded rods, or lifting eyelets.

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Neodymium Cup Magnets

Neodymium Cup Magnets (Rare Earth Round Mounting Bases)