HH 20x7.2 [M4] / N38 - through hole magnetic holder

Strengths and weaknesses of NdFeB magnets.

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

• Their power remains stable, and after around 10 years it drops only by ~1% (theoretically),
• They maintain their magnetic properties even under strong external field,
• In other words, due to the reflective layer of nickel, the element gains a professional look,
• Magnetic induction on the top side of the magnet turns out to be strong,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the shape) even at a temperature of 230°C or more...
• Thanks to freedom in designing and the capacity to adapt to complex applications,
• Universal use in advanced technology sectors – they are commonly used in computer drives, brushless drives, advanced medical instruments, also industrial machines.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

Characteristics of disadvantages of neodymium magnets and ways of using them

• Susceptibility to cracking is one of their disadvantages. Upon intense impact they can break. We recommend keeping them in a special holder, which not only protects them against impacts but also increases their durability
• When exposed to high temperature, neodymium magnets experience a drop in force. Often, when the temperature exceeds 80°C, their power decreases (depending on the size, as well as shape of the magnet). For those who need magnets for extreme conditions, we offer [AH] versions withstanding 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 stable to moisture, when using outdoors
• Limited ability of creating nuts in the magnet and complicated shapes - preferred is casing - magnetic holder.
• Potential hazard resulting from small fragments of magnets can be dangerous, in case of ingestion, which becomes key in the context of child health protection. Additionally, tiny parts of these devices can complicate diagnosis medical in case of swallowing.
• With large orders the cost of neodymium magnets is a challenge,

Breakaway strength of the magnet in ideal conditions – what it depends on?

The force parameter is a result of laboratory testing executed under standard conditions:

• with the contact of a yoke made of low-carbon steel, guaranteeing full magnetic saturation
• with a cross-section of at least 10 mm
• with an polished touching surface
• without the slightest air gap between the magnet and steel
• under vertical force vector (90-degree angle)
• at ambient temperature approx. 20 degrees Celsius

Determinants of practical lifting force of a magnet

It is worth knowing that the magnet holding may be lower subject to the following factors, in order of importance:

• Gap (betwixt the magnet and the metal), since even a very small distance (e.g. 0.5 mm) leads to a drastic drop in force by up to 50% (this also applies to paint, corrosion or dirt).
• Force direction – remember that the magnet holds strongest perpendicularly. Under sliding down, the capacity drops drastically, often to levels of 20-30% of the nominal value.
• Substrate thickness – for full efficiency, the steel must be adequately massive. Thin sheet restricts the lifting capacity (the magnet "punches through" it).
• Steel type – low-carbon steel gives the best results. Higher carbon content lower magnetic properties and lifting capacity.
• Smoothness – ideal contact is possible only on smooth steel. Rough texture reduce the real contact area, weakening the magnet.
• Thermal factor – hot environment reduces pulling force. Too high temperature can permanently damage the magnet.

* Lifting capacity testing was carried out on plates with a smooth surface of optimal thickness, under a perpendicular pulling force, in contrast under shearing force the holding force is lower. In addition, even a minimal clearance {between} the magnet and the plate decreases the holding force.