We can offer minimum sizes of sintered Neodymium magnets.
– Such micro-cylinders come with diameters as small as 0.5mm.
– Roughly the size of a mechanical pencil lead and custom lengths from 1mm to 10mm.
At this microscopic scale, standard Nickel plating is often too thick (adding 20+ microns) and too slippery for assembly.
Instead, we offer Red Shellac Coating.
This traditional industrial resin acts as a surface binder.
It seals the brittle magnetic powder while adding negligible thickness.
It provides a “tacky” surface texture that grips incredibly well into machined holes.
This feature makes it the preferred choice for micro-instrumentation, horology (watchmaking), and precision sensor assemblies.
Why Shellac?
In the world of micro-parts, standard plating can cause failure.
Here is why Shellac is the engineer’s choice for the tiniest magnets:
1. Dimensional Preservation (Zero-Bulk):
The Problem:
– A standard Ni-Cu-Ni coating adds ~20 microns to the diameter.
– On a 0.5mm magnet, this is a 4% dimensional change, which can ruin a precision press-fit.
The Shellac Solution:
– Shellac is an ultra-thin infiltration coating (approx. 5–8 microns).
– It seals the magnet against oxidation without significantly altering the tolerance of the raw machined part.
2. The “Grip” Factor (Adhesion):
The Problem:
– Nickel is smooth and slippery.
– Glue often fails on micro-nickel parts because there is no surface area for the adhesive to bite into.
The Shellac Solution:
– Shellac is naturally resinous.
– It acts as a primer, bonding aggressively with industrial epoxies and Loctite.
– If you are gluing a micro-magnet into a watch hand or a sensor needle, Shellac ensures it never falls out.
3. Gentle Processing:
The Physics:
– Tumbling 0.5mm magnets to plate them with Nickel often breaks them.
– Shellac coating is a gentle dipping/spraying process.
– It puts less mechanical stress on these fragile micro-rods during manufacturing.
Micro-Manufacturing Capabilities
Dimensional Range:
Diameter (Ø): 0.5mm – 2.0mm.
Length (L):
– 1.0mm – 10.0mm.
– We can customize the Aspect Ratio to suit your housing depth.
Tolerances:
Standard: ±0.03mm.
Precision: ±0.01mm (Available upon request for Swiss-style turned parts).
Magnetic Grade: N48 – N52.
– Since the volume is tiny, we almost exclusively use high-grade material.
– Ensure the magnet is actually functional despite its microscopic size.
Handling & Assembly Advisory
Working with 0.5mm magnets requires specific protocols.
Tweezers Only:
– These magnets are too small to handle by hand.
– Non-magnetic (ceramic or brass) tweezers are required.
The “Dust” Warning:
– A cluster of 0.5mm magnets looks like a pile of crumbs.
– If dropped, they are difficult to find.
– We recommend opening packages over a white tray.
Moisture Sensitivity:
– Shellac is a basic protective coating.
– It is not suitable for underwater use or high-humidity environments.
– It is designed for protected internal assemblies (e.g., inside a sealed device case).
Ideal Applications
Horology (Watchmaking): Micro-rotors or magnetic latches inside mechanical movements.
Micro-Guidance Systems: Steering magnets in catheter tips or endoscopes.
Optical Instrumentation: Actuating tiny mirrors or lenses in laser systems.
Micro-Sensors: Hall effect triggers for miniature switches.
Ordering Guide: Specifying Micro-Magnets
To quote these accurately, we need to know:
1). Exact Dimensions: Diameter x Length (e.g., Ø0.5 x 3mm).
2). Tolerance Requirements: “Is this being glued into a hole? What is the hole size?”
3). Application Environment: “Is this an internal dry assembly?” (Verifying Shellac is suitable).
4). Quantity: (Due to the difficulty of handling, MOQ for micro-magnets is typically higher, e.g., 1,000+ pcs).
