MW 20x5 / N38 - cylindrical magnet

Strengths and weaknesses of NdFeB magnets.

Besides their remarkable strength, neodymium magnets offer the following advantages:

• Their power is maintained, and after around ten years it drops only by ~1% (according to research),
• They maintain their magnetic properties even under strong external field,
• By using a decorative coating of nickel, the element acquires an nice look,
• Neodymium magnets ensure maximum magnetic induction on a contact point, which ensures high operational effectiveness,
• Through (appropriate) combination of ingredients, they can achieve high thermal strength, allowing for operation at temperatures approaching 230°C and above...
• Possibility of custom machining and adjusting to concrete applications,
• Universal use in innovative solutions – they are commonly used in HDD drives, electric motors, diagnostic systems, and complex engineering applications.
• Compactness – despite small sizes they offer powerful magnetic field, making them ideal for precision applications

Disadvantages of NdFeB magnets:

• To avoid cracks upon strong impacts, we suggest using special steel holders. Such a solution protects the magnet and simultaneously increases its durability.
• Neodymium magnets lose their power under the influence of heating. As soon as 80°C is exceeded, many of them start losing their power. Therefore, we recommend our special magnets marked [AH], which maintain durability even at temperatures up to 230°C
• Due to the susceptibility of magnets to corrosion in a humid environment, we recommend using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• Limited ability of producing threads in the magnet and complicated forms - recommended is cover - magnet mounting.
• Potential hazard resulting from small fragments of magnets pose a threat, if swallowed, which becomes key in the aspect of protecting the youngest. Furthermore, small elements of these devices are able to disrupt the diagnostic process medical after entering the body.
• High unit price – neodymium magnets are more expensive than other types of magnets (e.g. ferrite), which hinders application in large quantities

Best holding force of the magnet in ideal parameters – what affects it?

Breakaway force was determined for the most favorable conditions, taking into account:

• using a sheet made of mild steel, acting as a ideal flux conductor
• with a cross-section of at least 10 mm
• with an ground touching surface
• without any air gap between the magnet and steel
• for force applied at a right angle (pull-off, not shear)
• at conditions approx. 20°C

What influences lifting capacity in practice

During everyday use, the actual holding force is determined by many variables, ranked from crucial:

• Clearance – the presence of foreign body (paint, tape, gap) interrupts the magnetic circuit, which lowers power rapidly (even by 50% at 0.5 mm).
• Direction of force – highest force is available only during pulling at a 90° angle. The resistance to sliding of the magnet along the surface is typically many times lower (approx. 1/5 of the lifting capacity).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet limits the lifting capacity (the magnet "punches through" it).
• Material type – the best choice is high-permeability steel. Cast iron may attract less.
• Smoothness – full contact is possible only on smooth steel. Any scratches and bumps create air cushions, reducing force.
• Thermal environment – temperature increase causes a temporary drop of force. Check the thermal limit for a given model.

* Lifting capacity was measured with the use of a smooth steel plate of optimal thickness (min. 20 mm), under vertically applied force, however under parallel forces the load capacity is reduced by as much as 5 times. Additionally, even a small distance {between} the magnet and the plate decreases the lifting capacity.