Attaching Magnets with Screws & Bolts

Attaching magnets with screws is one of the most reliable ways to mount magnets when you need a highly secure attachment, repeatable positioning, and good resistance to shock, vibration, and long-term handling. A properly clamped magnet doesn’t creep like tape, doesn’t age like many adhesives, and it’s easy to service or replace without destroying the surrounding parts.

This guide covers the practical details that make screw mounting work in the real world: hardware choices (screw materials, head styles, washers, and thread-locking options), magnet hole styles (countersunk, counterbored, thru-hole, and steel cup/housing options), and installation practices that prevent the most common failures — cracking brittle magnets, screws backing out, and corrosion from damaged plating or wet environments. The goal is simple: keep the magnet seated flat, keep clamp load stable for the life of the product, and avoid introducing gaps or stress risers that reduce holding force and increase breakage.

Disclaimer:

Screws Vs Other Attachment Methods

Screws are the “mechanical insurance policy” option. They’re predictable, removable, and very secure, especially when the product might be dropped, vibrated, heated, or exposed to moisture. The problem with glues and adhesive tapes: Adhesives can fail over the long term, and it’s hard to verify bond quality during assembly. Screws don’t depend on surface cleanliness or cure conditions, and they’re easy to validate on the line.

Magnetic Vs Non-Magnetic Screws

Choosing a magnetic (ferromagnetic) screw versus a non-magnetic screw can meaningfully change how a magnet assembly performs.

A magnetic (steel) screw can improve magnet performance by providing a low-reluctance path for the flux to travel through, often increasing holding force. Pairing it with a steel washer/backer can boost performance further by directing the flux and reducing field leakage. A non-magnetic screw (brass, aluminum, and many stainless grades) won’t help the magnetic circuit as the flux ignores these materials.

Non-Ferromagnetic Screw	Ferromagnetic Screw
Force results may vary	Force results may vary

Non-Ferromagnetic Screws

The magnetic field will virtually ignore non-ferromagnetic materials. These screws are essentially “invisible” to the magnetic circuit, so they do not increase holding force. Choose these when you want the screw to be purely mechanical (mounting/retention) and not part of the magnet’s performance.

Material	Appearance	Typical relative permeability, μr	Force results will vary	Force results may vary
Stainless Steel (300 Series)		~1.003 -1.02μ (Not Ferromagnetic)	Force results will vary
Titanium		~1.0 μ (Not Ferromagnetic)	Force results will vary
Aluminum		~1.0 μ (Not Ferromagnetic)	Force results will vary
Brass		~1.0 μ (Not Ferromagnetic)	Force results will vary
Copper		~1.0 μ (Not Ferromagnetic)	Force results will vary

Ferromagnetic Screws

A ferromagnetic screw can give a small performance boost because it can act like a low-reluctance flux path through the center of the magnet assembly. How much it helps depends on the magnet size, thickness, and polarity orientation.

In typical real assemblies, the increase in holding force is usually 0–20%, and in many cases it’s closer to “a little” than “a lot.”

Treat it as a bonus, not the main performance lever. If you need a big step up in force, the washer/backer shown below is the right tool.

Material	Appearance	Typical relative permeability, μr	Force results will vary	Force results may vary
Stainless Steel (400 Series)		~100–500 μ e.g., 430 SS (Ferromagnetic)	Force results will vary
Black-Oxide Alloy Steel		~200-800 μ (Ferromagnetic)	Force results will vary
Zinc-Plated Alloy Steel		~200-800 μ (Ferromagnetic)	Force results will vary
Low Carbon Steel		~200-800 μ e.g., 1018 LCS (Ferromagnetic)	Force results will vary

Ferromagnetic Washer/Backer

Adding a ferromagnetic washer (or backer plate) behind the magnet can greatly increase holding force because it provides a much larger, more effective return path for the flux and helps reduce “wasted” leakage field behind the magnet.

This is often the single easiest way to increase performance without changing the magnet itself.

A realistic performance increase is often 10–150%, depending on geometry and materials.

Best practice is to use a washer/backer that is wider than the magnet. Wider is generally better, but you’ll hit diminishing returns as you keep increasing diameter/area. Balance performance against cost, packaging space, and weight. If you can’t go wider, a washer about the same size as the magnet can still help quite a bit.

Material	Appearance	Typical relative permeability, μr	Force results will vary	Force results may vary
Stainless Steel (400 Series)		~100–500 e.g., 430 SS (Ferromagnetic)	Force results will vary
Black-Oxide Coated Alloy Steel		~200-800 (Ferromagnetic)	Force results will vary
Zinc-Plated Alloy Steel		~200-800 (Ferromagnetic)	Force results will vary
Low Carbon Steel		~200-800 e.g., 1018 LCS (Ferromagnetic)	Force results will vary
Pure Iron		~2000-10000 (Ferromagnetic)	Force results will vary

Proper Screw Installation

Proper screw installation is where things either go right, or you end up with a cracked magnet, a breached coating, or a loose assembly. The goal is simple: keep the pressure even, keep the magnet seated flat, and make sure the hardware stays tight over time.

Screw Taper Angle

• Match the countersink angle in the magnet to the screw head angle so the screw head seats fully and spreads pressure evenly. If the angles don’t match, the head contacts in a thin ring, which creates high stress and chips plating or cracks the magnet during tightening. And it can wear away the plating if the device experiences vibration or movement from constant attaching and detaching.
• Common angles you’ll run into: 82° (many imperial flat heads), 100° (some imperial/structural and specialty flat heads), and 90° (common metric flat heads). The exact standard depends on the screw family, so don’t assume.

82° Taper (Flat Head) Typical for Imperial Screws	90° Taper (Flat Head) Typical for Metric Screws	100° Imperial (Flat Head) Special Imperial Screws
Pan Head Screws Fit Counterbore Magnets	Socket Head Screws Fit Counterbore Magnets	82° Wood Screws Typical for Wood Screws

	Over-Tightening Concerns More torque is not “more secure” once the magnet is seated. Over-tightening can crush the countersink edge, start a crack in the brittle NdFeB, or breach the coating. This gets worse fast if the taper angles don’t match, because the load is concentrated instead of distributed. Use controlled torque and stop as soon as the magnet is firmly seated and cannot rock.
	Thread Locking If the assembly will see vibration, temperature cycling, or repeated impacts, assume the screw will eventually try to back out. Use a thread-locking strategy that matches the product: threadlocker “glue” (removable or permanent), nylon patch, lock nut, or a locking washer. The goal is simple: keep clamp load consistent for the life of the product.
	The Importance of the Screw Angle The screw head angle is not just a “fit” issue, it directly controls the stress in the magnet. A matched countersink spreads load across a larger area and seats the head cleanly. A mismatched angle concentrates pressure at a thin ring, which is exactly how you chip plating and crack brittle magnets when you tighten. It also affects holding force. If the screw doesn’t seat fully below the attaching face of the magnet, it can create an air gap that lowers the pull force of the magnet. Even a tiny gap can noticeably reduce pull force.
	Coating Breach For NdFeB magnets, the coating is your corrosion barrier. A small scratch at the countersink edge caused by a misalignment of the countersink angles or a screw inserted at a bad angle can become the starting point for rust, swelling, and eventually failure. Use controlled torque, avoid sharp edges, and consider a washer or finishing washer when it helps distribute load without causing rocking.

Flush Mount Magnets

For a flush-mounted countersunk magnet, the magnet needs to sit flat on the bottom of the pocket before you ever tighten the screw. If the pocket has a cone-shaped bottom, a ridge, or a burr, the magnet will “rock” and the screw will clamp it unevenly. That’s how you end up with chipped plating, cracked magnets, and loosening over time.

Methods good for flat seating:

End mill (best choice) Creates a true flat-bottom pocket
Forstner bit For a clean, flat-bottom recess
Counterbore cutter or Spotfacer Flattens the bottom and creates a through hole. Make sure the through hole is not too large to fit the screw threads if you plan to screw the magnet into the same material.
AVOID: Standard Twist Drill Bits leaves a conical bottom which makes it very difficult to seat the magnet flush in the pocket.

The Importance of Pocket Depth

If you don’t properly control the pocket depth, you may overshoot the hole depth, causing the magnet to sit too far down inside the pocket. If the magnet is further away from the target, the force will reduce significantly. Even small gaps can create large performance drops.

What if you did go too deep? Add a steel washer behind the magnet to bring it closer to the surface. This not only reduces the gap, but the steel backer can significantly increase your pull force.

Pocket Too Deep

Corrected with Steel Washer

Magnets With Screw and Nut Mounting Options

This section is a quick tour of the main “screw-mount” magnet styles you’ll run into at AmazingMagnets.com. Each option solves a slightly different problem: flush mounting, higher durability, better corrosion protection, or easier installation when you only have access from one side

	Countersunk Neodymium Magnets A simple magnet with a tapered hole for a flat-head screw so the head sits flush. Clean and low-profile, but the magnet is brittle and the countersink edge is easy to chip if the screw angle is wrong or the screw is over-tightened.
	Attracting	Repelling	If you want to attach a countersunk magnet to another countersunk magnet then you will need one magnet with a countersink on the north pole and another with the countersink on the south pole because opposite poles attract.
	Counterbore Neodymium Magnets A magnet with a straight counterbore pocket for a socket head or pan head screw. The screw head has a flat bearing surface, which can be gentler on the magnet than a countersink, and it’s easier to get consistent seating without concentrating stress.
	Countersunk Neodymium Cup Magnets A countersunk magnet captured in a steel cup. The cup protects the magnet, spreads the load, and usually increases the holding force by providing a low-reluctance path. This is often the better “default” when you need a countersunk fastener but want durability and extra power when attaching to a metal surface.
	Counterbore Neodymium Cup Magnets A cup magnet with a counterbore style mounting hole. You get the protection and performance boost of the steel cup, plus the more forgiving, flat head contact of a counterbore. Great for shock, vibration, and real-world abuse.
	Male Threaded Neodymium Cup Magnets A cup magnet with an external threaded stud. Fast installation, easy positioning, and no need to pass a screw through the magnet. Best when you can only access one side and want a clean, repeatable mounting method.
	Female Threaded Post Neodymium Cup Magnets These are cup magnets with a raised, female-threaded post on the top side. You mount your bracket or part by running a screw into the post from above. This gives you a little standoff height, keeps the hardware on the “working side,” and is handy when you don’t want a protruding stud or a nut on the back.
	Internal Threaded Neodymium Cup Magnets These are cup magnets with threads built into the cup magnet body itself (the threaded hole goes into the assembly rather than a raised post). You run a screw directly into the magnet assembly. This is the cleanest, lowest-profile threaded option, and it’s ideal when you want the magnet to sit tight to a surface with minimal extra height.