N35 Neodymium Cylinder Magnet 4mm x 25mm - Buy for Electronics Projects

Quick Specification Overview

When you see "N35 neodymium 4x25mm cylinder", these are the key attributes to confirm before buying: material grade (N35), shape (cylindrical), diameter (4 mm), length (25 mm), coating (nickel, zinc or epoxy), and polarity (axial through the cylinder). These attributes determine field strength, corrosion resistance, and mechanical handling requirements.

Typical spec table

Why N35 and where it suits best

N35 is a common neodymium magnet grade that provides strong flux density for its size while remaining one of the more economical grades. For a 4x25mm cylinder, N35 gives a good balance of pull force and cost for hobby electronics, sensor trigger magnets, magnetic latches, and light-duty magnetic couplings in robotics or moving assemblies. See uses in robotics projects for examples.

Practical project uses

• Reed switch or hall-effect sensor activation (ensure face orientation matches sensor geometry). — How to use cylinder magnets in electronics
• Magnetic mounting for small PCBs, enclosures, or removable panels.
• Rotor magnets for small brushless motors or DIY encoders (observe safe separation distances).
• Magnetic couplers for sealed shafts where a mechanical feedthrough is undesirable.

Selection & Compatibility Guidance

Match magnet size and grade to your sensor or assembly. For hall sensors specify required field strength at the sensor's switch distance. For reed switches, confirm the required pull-in distance with a supplier datasheet or test sample. Note that two faced magnets produce different fields than ring or disc magnets, so always verify geometry against the sensor mounting.

Handling, safety and assembly notes

• Neodymium magnets are brittle; avoid sharp impacts and clamp/pinch risks during assembly.
• Strong magnets can affect magnetic storage and nearby sensors; keep safe clearances from compasses, credit cards and sensitive electronics.
• If mounting inside metal housings, remember ferrous materials will change the effective field and pull force; allowance for shielding/air gap is needed.

Practical examples and calculations

Exact pull force depends on grade, plating, and mounting. As an example of how to think in practical terms: if a cylindrical magnet is used to trip a hall sensor at 5 mm distance, confirm the sensor's switching flux threshold in its datasheet and test with a single sample before committing to a batch. For load-bearing magnetic latches, use magnets rated with pull force specified by the supplier and include at least 25-50% safety margin for vibration and surface finish variability. Where you need to estimate field decay with distance, remember magnetic flux density typically falls quickly (roughly with inverse square or faster depending on geometry) so doubling the distance can reduce field substantially.

Accessory and bundle suggestions

• Adhesive disks or mounting cups for secure placement in plastic/wood housings.
• Thin non-ferrous spacers (plastic or brass) to set precise sensor gaps.
• Protective coatings or epoxy for magnets used in humid or corrosive environments.

Choosing a supplier and testing

Buy a small sample to verify polarity, coating, and fit before purchasing bulk. When testing, use a non-ferrous jig to measure switch distance to a hall sensor or reed switch and record values for repeatability. For classroom or maker-space purchases, buy extra for spares and include safe handling training for students and technicians.

Sources

• Overview of neodymium magnets - Wikipedia
• Magnet supply reference and datasheets - K&J Magnetics
• Communica product categories and collections
• Communica branches and collection details