We supply precision-ground Flat Ring Neodymium Magnets (also known as Magnetic Washers or “Donut” Magnets).
As shown in our product example (22 mm OD×1.5 mm T), these components feature a low-profile, flat geometry with a central clearance hole.
They can integrate seamlessly with standard hardware.
And function as magnetic spacers or locking washers in assemblies where vertical space is restricted.
These Straight-Hole Rings are for “Pass-Through” applications.
They allow a bolt, shaft, or axle to pass freely through the center.
Meanwhile, the magnet provides a clamping force on the surrounding flat face.
Why use a Magnetic Washer?
1. “Zero-Profile” Fastening:
The Application:
– Adding magnetism to a bolt or screw.
The Function:
– Slide this magnet onto a non-magnetic screw (like a washer).
The Benefit:
– It instantly turns a standard screw into a magnetic catch or latch.
– But without requiring complex housing or glue.
– The 1.5mm thickness is designed to fit under standard screw heads, but not interfering with the thread engagement.
2. Shaft Collars & Spacers:
The Function:
– The ring fits over a rotating shaft.
The Benefit:
– It can act as a magnetic spacer to repel other components (magnetic bearings) or trigger a stationary sensor as the shaft rotates.
Expert Warning: Fragility (The “Snap” Risk)
A 22 mm ring that is only 1.5 mm thick is extremely fragile.
Handling Thin Rings:
Please note that Sintered Neodymium is a brittle ceramic.
A ring with this High Diameter-to-Thickness Ratio (22:1.5) is sensitive to bending forces.
Installation:
– It must be installed against a perfectly flat surface.
– If you screw it down onto an uneven surface, the torque will crack the ring instantly.
Torque:
– Do not over-tighten the screw passing through the hole.
– The washer is designed for clamping magnetic force, not structural compression force.
Magnetization Orientation
Axial (Through Thickness):
– The standard.
– One flat face is North, the other is South.
– This is used for clamping/holding.
Diametric:
– Magnetized across the diameter.
Use:
– If the ring is placed on a shaft to trigger a Hall Effect rotational sensor.
Surface Coatings
Nickel (Ni-Cu-Ni):
– As shown.
– Provides a clean, bright finish.
Zinc (Zn):
– Good for industrial washers.
Parylene:
– Recommended if the washer is used in a fluid environment (e.g., inside a valve).
Rubber Coated:
– We can coat larger rings in rubber to provide friction.
– And prevent the magnet from sliding down a vertical surface.
Applications
Magnetic Fasteners: Holding signs or covers where a screw is present.
Suspension Systems: Repelling magnet rings on a shaft (Magnetic Spring).
Sensors: “Floating” ring magnets for liquid level sensors.
Crafts & Closures: Sew-in magnets for handbags (the hole allows for stitching).
Ordering Guide: What We Need
To quote this, we need 3 dimensions:
1). OD: Outer Diameter (22 mm).
2). ID: Inner Diameter (Hole Size).
– Tip: Tell us “Fits M5 screw” and we will calculate the clearance.
3). Thickness: (1.5 mm).
4). Quantity: (Thin rings are produced in large batches).
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