We offer custom disc Neodymium magnets with scalloped edges.
They have cutouts or notches machined into the outer circumference.
Typically combined with a central mounting hole.
The scallops serve multiple functions:
– Mechanical anti-rotation (the magnet cannot spin in a housing with matching features).
– Clearance for wires or cables passing alongside the magnet.
– Fluid flow-through in sealed assemblies.
The geometry can be symmetric (e.g., three evenly spaced scallops).
Or asymmetric (single keyway notch for indexed orientation).
Common in sensor housings, actuators, pumps.
And assemblies where precise rotational alignment or cable routing is required.
The Engineering Logic: Why the “Scallops”?
1. Anti-Rotation (The Locking Feature):
A standard ring magnet secured by a single central screw can loosen and spin under vibration.
The Solution:
– The scallops on the outer edge fit against molded posts or pins in your plastic/metal housing.
The Benefit:
– The magnet is mechanically locked.
– It cannot rotate, ensuring that sensors remain aligned or that the screw does not back out over time.
2. Component Clearance:
The Function:
– In tight electronic assemblies, you may need to run wires or fit a screw pillar right next to the magnet.
The Benefit:
– The cutout provides a “tunnel” for wires.
– Or other components to pass by the magnet without increasing the overall assembly height.
Production Method: Precision Wire EDM
Standard grinding wheels cannot cut these side notches easily.
We need to make good use of cutting techniques.
No Tooling Costs for Custom Shapes:
To achieve the complex perimeter profile shown in the photo, we use Wire Electrical Discharge Machining.
Flexibility:
– We can cut any notch shape – round, square, or V-shaped – directly from your CAD file.
Cost Efficiency:
– Unlike stamped parts, there is no expensive mold fee for Wire EDM.
– This makes it ideal for prototyping or small-to-medium production runs of custom shapes.
Tolerance:
– We hold profile tolerances of ±0.03mm.
– Ensure the notches fit your housing posts snugly.
Magnetization Orientation
Axial (Through Thickness):
– The standard.
– The flat face with the hole is the North/South pole.
Multi-Pole:
– We can also supply these with multi-pole magnetization on the face for sensor triggers (rotary encoders).
Surface Coatings
Nickel (Ni-Cu-Ni):
– As shown.
– Provides a clean, durable finish that covers the inside of the notches and the center hole evenly.
Epoxy:
– Recommended if the magnet is exposed to moisture or outdoor elements.
Parylene:
– For medical or micro-fluidic applications.
– The scallops might allow fluid to flow past.
Applications
Sensor Mounts: The scallops lock the magnet in a specific angular orientation for accurate Hall Effect sensing.
Motor Assemblies: Custom stators where the notches allow for cooling airflow or wire routing.
Fluid Systems: The cutouts allow oil or water to flow around the magnet while it captures ferrous debris.
Automotive Sensors: Vibration-proof mounting points.
Ordering Guide: What We Need
Standard dimensions (OD/ID/Thickness) are not enough.
We require a Drawing or the following details:
1). Outer Diameter (OD): The full diameter.
2). Inner Diameter (ID): The center hole size.
Notch Detail:
3). How many notches? (e.g., 3 scallops).
4). What is the Radius or Width of the notch?
5). What is the Bolt Circle Diameter (BCD) or position of the notches?
6). Thickness: The height.
Note:
Please provide a DXF or DWG file for the fastest quotation.
