MP 30x6x10 / N38 - ring magnet

Advantages as well as disadvantages of NdFeB magnets.

In addition to their pulling strength, neodymium magnets provide the following advantages:

• Their strength is durable, and after around 10 years it decreases only by ~1% (theoretically),
• They possess excellent resistance to magnetism drop when exposed to external magnetic sources,
• The use of an refined layer of noble metals (nickel, gold, silver) causes the element to present itself better,
• The surface of neodymium magnets generates a powerful magnetic field – this is a distinguishing feature,
• Through (adequate) combination of ingredients, they can achieve high thermal resistance, enabling action at temperatures reaching 230°C and above...
• Thanks to flexibility in constructing and the ability to modify to unusual requirements,
• Wide application in future technologies – they are used in mass storage devices, electric motors, diagnostic systems, also other advanced devices.
• Thanks to concentrated force, small magnets offer high operating force, in miniature format,

Drawbacks and weaknesses of neodymium magnets: application proposals

• At very strong impacts they can break, therefore we recommend placing them in strong housings. A metal housing provides additional protection against damage, as well as increases the magnet's 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
• Magnets exposed to a humid environment can corrode. Therefore during using outdoors, we suggest using water-impermeable magnets made of rubber, plastic or other material protecting against moisture
• We suggest a housing - magnetic holder, due to difficulties in creating threads inside the magnet and complicated forms.
• Potential hazard resulting from small fragments of magnets pose a threat, in case of ingestion, which becomes key in the aspect of protecting the youngest. Additionally, tiny parts of these products are able to be problematic in diagnostics medical after entering the body.
• Due to complex production process, their price is relatively high,

Maximum magnetic pulling force – what affects it?

Information about lifting capacity is the result of a measurement for the most favorable conditions, assuming:

• using a base made of high-permeability steel, acting as a circuit closing element
• with a thickness of at least 10 mm
• with an ground touching surface
• with direct contact (no paint)
• under vertical force vector (90-degree angle)
• at room temperature

Determinants of practical lifting force of a magnet

Bear in mind that the magnet holding may be lower subject to the following factors, in order of importance:

• Air gap (betwixt the magnet and the metal), since even a very small distance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Force direction – note that the magnet holds strongest perpendicularly. Under shear forces, the holding force drops drastically, often to levels of 20-30% of the nominal value.
• Steel thickness – insufficiently thick steel does not accept the full field, causing part of the flux to be lost to the other side.
• Chemical composition of the base – low-carbon steel gives the best results. Alloy steels decrease magnetic properties and holding force.
• Surface finish – full contact is obtained only on smooth steel. Rough texture create air cushions, reducing force.
• Operating temperature – neodymium magnets have a sensitivity to temperature. At higher temperatures they are weaker, and in frost gain strength (up to a certain limit).

* Lifting capacity was measured with the use of a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular detachment force, in contrast under parallel forces the lifting capacity is smaller. In addition, even a minimal clearance {between} the magnet and the plate lowers the lifting capacity.