MW 38x3.5 / N38 - cylindrical magnet

Strengths and weaknesses of NdFeB magnets.

In addition to their magnetic efficiency, neodymium magnets provide the following advantages:

• They retain full power for around ten years – the drop is just ~1% (in theory),
• They are extremely resistant to demagnetization induced by external magnetic fields,
• Thanks to the smooth finish, the plating of Ni-Cu-Ni, gold, or silver-plated gives an clean appearance,
• Neodymium magnets ensure maximum magnetic induction on a their surface, which increases force concentration,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and are able to act (depending on the form) even at a temperature of 230°C or more...
• Thanks to versatility in shaping and the ability to customize to client solutions,
• Universal use in future technologies – they are commonly used in computer drives, drive modules, diagnostic systems, as well as technologically advanced constructions.
• Thanks to their power density, small magnets offer high operating force, with minimal size,

Drawbacks and weaknesses of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We advise keeping them in a special holder, which not only secures them against impacts but also increases their durability
• We warn that neodymium magnets can lose their strength at high temperatures. To prevent this, we suggest our specialized [AH] magnets, which work effectively even at 230°C.
• Due to the susceptibility of magnets to corrosion in a humid environment, we advise using waterproof magnets made of rubber, plastic or other material immune to moisture, in case of application outdoors
• We suggest cover - magnetic holder, due to difficulties in creating nuts inside the magnet and complicated forms.
• Potential hazard resulting from small fragments of magnets can be dangerous, when accidentally swallowed, which becomes key in the context of child health protection. It is also worth noting that small elements of these products are able to disrupt the diagnostic process medical after entering the body.
• Due to neodymium price, their price is relatively high,

Maximum holding power of the magnet – what it depends on?

Information about lifting capacity is the result of a measurement for ideal contact conditions, assuming:

• using a plate made of high-permeability steel, serving as a magnetic yoke
• possessing a massiveness of minimum 10 mm to avoid saturation
• with a plane perfectly flat
• with direct contact (no coatings)
• for force acting at a right angle (pull-off, not shear)
• at temperature approx. 20 degrees Celsius

Practical aspects of lifting capacity – factors

It is worth knowing that the application force will differ subject to elements below, in order of importance:

• Space between magnet and steel – every millimeter of distance (caused e.g. by varnish or unevenness) diminishes the magnet efficiency, often by half at just 0.5 mm.
• Force direction – catalog parameter refers to pulling vertically. When attempting to slide, the magnet holds much less (typically approx. 20-30% of maximum force).
• Substrate thickness – for full efficiency, the steel must be adequately massive. Paper-thin metal limits the lifting capacity (the magnet "punches through" it).
• Metal type – not every steel reacts the same. Alloy additives weaken the attraction effect.
• Surface finish – full contact is possible only on polished steel. Any scratches and bumps create air cushions, weakening the magnet.
• Operating temperature – neodymium magnets have a negative temperature coefficient. When it is hot they are weaker, and at low temperatures gain strength (up to a certain limit).

* Holding force was checked on the plate surface of 20 mm thickness, when the force acted perpendicularly, whereas under attempts to slide the magnet the lifting capacity is smaller. Additionally, even a small distance {between} the magnet and the plate lowers the lifting capacity.