Holding force: The attractive force of magnets

The adhesive force describes the strength with which a magnet adheres to a magnetic surface. It is measured in the unit Newton (N) and indicates how much weight or load a magnet can hold before it tears away from the surface. The holding force is one of the most important properties of a magnet, especially in practical applications such as fastening, lifting technology and construction.

How is the holding force calculated?

The holding force of a magnet depends on several factors that influence its ability to hold a magnetic surface:

• Magnetic flux density: The higher the flux density of the magnet, the stronger the holding force.
• Contact area: A larger contact area between the magnet and the surface increases the adhesive force.
• Surface material: Materials with high permeability, such as iron or steel, increase the adhesive force. Aluminium or wood, on the other hand, are not magnetic and do not affect the adhesive force.
• Surface finish: Smooth and clean surfaces improve the adhesive force, while rough or dirty surfaces reduce it.

Typical values for adhesive force

• Neodymium magnets: Adhesive forces of 5-200 kg depending on size and shape.
• Death magnets: holding forces of 200-2,000 kg depending on size and shape.
• Ferrite magnets: holding forces of 0.5-20 kg, depending on size.
• Electromagnets: Holding forces can reach several tonnes, e.g. in industrial lifting magnets.

How is the holding force tested?

The holding force is usually measured using a force gauge. A magnet is applied to a magnetic surface and the tensile force required to release the magnet from the surface is measured. This method provides precise results and is often used in quality control. It is particularly important that the applied tensile force is applied at the correct angle to the magnet, as any deviation can affect the values and lead to an inaccurate reading.

Applications of adhesive force

The adhesive force is a decisive factor in many areas of technology and everyday life:

• Industrial lifting magnets: For lifting heavy metal parts in production and logistics.
• Magnetic fasteners: For tool holders, magnetic boards or door fasteners.
• Electric magnets: In crane systems and robots where controlled holding forces are required.
• Medical technology: In surgical tools and implants that are based on magnets.

Interesting facts about holding force

Did you know that the holding force of a magnet depends not only on its size, but also on its shape? Flat magnets often have a higher adhesive force than spherical magnets as they offer a larger contact surface. Magnets can also increase their adhesive force even further through special arrangements, such as the combination of several magnets.