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Female Threaded Cup Magnets
Internal Threaded Bushing & Collar Mount Assemblies
Female Threaded Cup Magnets (Internal Thread Mounting Bases)
CMS Magnetics engineers industrial-grade female threaded cup magnets (also termed female threaded pot magnets or internal thread mounting bases) built for heavy-duty hardware attachments, suspended ceiling rigging, and modular tooling fixtures. Each assembly encloses a high-energy sintered NdFeB permanent magnet inside a precision-machined, triple-plated mild steel cup fitted with a raised cylindrical steel boss containing internal standard threads. The steel cup serves as a high-efficiency magnetic shunt, focusing magnetic saturation directly onto the front contact rim to generate up to 5x the direct perpendicular pull force of an unencased magnet, while the rear female threaded bushing accepts standard machine bolts, threaded rods, eye bolts, and lifting hooks without placing stress on the brittle neodymium core.
Looking for external studs, flush screws, or rectangular bases? For assemblies with protruding threaded shanks, explore our Male Threaded Cup Magnets. For flat-head screw mounting flush to walls, view Countersunk Cup Magnets. If you need linear door latches, see Neodymium Channel Magnets, or pair assemblies with Steel Magnet Strikers.
Heavy-Duty Steel Boss
Raised cylindrical collar provides deep thread engagement to prevent stripping under tension.
Focused Flux Shunt
Steel cup directs magnetic lines forward to the rim, producing intense direct breakaway clamping.
Standard Thread Compatibility
Precision metric (M4, M5, M6, M8, M10) and imperial pitches mate with standard machine fasteners.
Triple Ni-Cu-Ni Armor
Electrolytic nickel plating protects the internal rare-earth core and outer steel cup from corrosion.
Filter by Cup & Assembly Style: Female Threaded Cup Magnets Male Threaded Cup Magnets Countersunk Cup Magnets Neodymium Channel Magnets All Neodymium Cups
Engineering Guide: Female Threaded Cup Magnet Mechanics, Thread Depth & Load Ratings
Female threaded cup magnets function as heavy-duty magnetic anchor points for mechanical equipment, overhead ceiling suspensions, lighting brackets, and removable fixturing. By integrating an internally tapped steel collar onto the rear of a ferromagnetic cup, these assemblies isolate the fragile sintered NdFeB magnet core from fastener engagement stresses while redirecting magnetic flux for maximum holding power.
Female Threaded Bushing Sizing & Pull Force Guide
| Cup Outer Diameter (OD) | Internal Thread Size | Direct Breakaway Pull Force | Max Vertical Shear Load | Primary Mechanical Installation |
|---|---|---|---|---|
| 0.79 in (20 mm) | M4 × 0.7 or #8-32 | 20 – 30 lbs | 3.0 – 5.0 lbs | Retail signage hooks, security camera brackets |
| 0.98 in (25 mm) | M5 × 0.8 or #10-24 | 40 – 55 lbs | 6.0 – 9.0 lbs | Electrical conduit mounts, light fixture hanging |
| 1.26 in (32 mm) | M6 × 1.0 or 1/4"-20 | 65 – 90 lbs | 10.0 – 15.0 lbs | Overhead ceiling rigging, eyebolt attachments, antenna bases |
| 1.89 in – 2.95 in (48 – 75 mm) | M8 × 1.25, M10, or 3/8"-16 | 160 – 400+ lbs | 25.0 – 65.0 lbs | Industrial machinery workholding, structural beam clamps |
Mechanical Advantages of Female Threaded Bushings
Choosing a female threaded cup magnet provides several distinct installation advantages over male threaded or countersunk designs:
- Interchangeable Fasteners: The internal thread accepts standard metric or imperial machine screws, custom-length threaded studs, eye bolts, swivel hooks, or ball-joint mounts, allowing one magnetic base to serve multiple fixture designs.
- Protection of Thread Integrity: Unlike male threaded studs whose exposed external threads can get damaged, bent, or nicked during transport or aggressive handling, female threads are protected inside the solid steel collar.
- Torque Distribution: Fastening into a raised steel collar prevents the bolt from bottoming out directly onto the brittle sintered NdFeB magnet, protecting the rare-earth core from mechanical cracking under high tightening torque.
Load Engineering: Perpendicular Breakaway vs. Vertical Shear Slide
Published holding values reflect direct perpendicular pull force (Case 1) tested on flat, clean, ground 1/2-inch structural low-carbon steel. When mounting female threaded cup magnets vertically on equipment frames or steel walls:
- The Sliding Friction Factor (μ): The coefficient of friction between smooth nickel-plated steel surfaces is approximately μ ≈ 0.15 – 0.20. Under pure gravity shear load, a vertical cup magnet will begin sliding downward at approximately 15% to 20% of its rated perpendicular pull force unless mechanically supported.
- Steel Substrate Thickness: To achieve maximum clamping force, the steel substrate must be at least 1/4" to 1/2" thick. Attaching to thin 18- or 20-gauge sheet metal results in premature magnetic saturation, allowing magnetic field lines to bleed through and cutting holding capacity by 50% or more.
- Non-Ferrous Mating: When mounting against wood beams, drywall, or non-magnetic aluminum panels, pair the assembly with matching Steel Magnet Strikers.
Frequently Asked Questions
What is the difference between a female threaded cup and an internal threaded hole cup?
A female threaded stud cup magnet features a raised cylindrical steel boss or collar welded to the back of the cup, providing a deeper thread engagement depth. An internal threaded hole cup typically features a thread tapped flush directly into the flat back of the steel cup or central steel pole piece.
Will screwing a bolt in too far damage the magnet inside?
Our female threaded assemblies are engineered with a solid steel floor or blind collar stop that prevents the bolt shank from contacting the internal sintered neodymium magnet. However, always select a bolt length matching the usable thread depth of the collar to ensure tight clamping against the collar shoulder.
What is the temperature limit for female threaded neodymium cup magnets?
Standard neodymium female threaded cup magnets are rated for maximum continuous operating temperatures of 80°C (176°F). Exceeding this limit causes permanent loss of magnetic pull force. For higher-temperature industrial environments, explore Ceramic Cup Magnets (up to 250°C) or AlNiCo Pot Magnets (up to 500°C).
Can I use female threaded cup magnets outdoors?
Yes, in dry or light outdoor environments. The entire assembly (steel cup, collar, and NdFeB core) is protected with a commercial triple-layer nickel-copper-nickel (Ni-Cu-Ni) electroplated finish. For continuous marine, salt-spray, or washdown conditions, apply an exterior silicone sealant or choose naturally corrosion-proof ceramic cup magnets.