Can magnetic fields be blocked?

Magnetism like a sponge?

To understand how permeability and saturation work, imagine a sponge. Some sponges have larger holes, others have a denser structure, but all absorb water up to a certain point. Similarly, with materials used to redirect magnetic fields: they have different permeability capacities and saturation points. Ultimately, the choice of material depends on specific applications and needs.

Protection against magnetic fields

One cannot block a magnetic field, but it can be redirected. This process is called "Magnetic Shielding." To achieve this, equipment requiring protection is placed inside a structure made of a material with high magnetic conductivity, such as steel. Magnetic field lines then flow through this material, protecting sensitive components, such as delicate electronics.

MuMetal® - Specialist among materials

MuMetal® is a unique alloy that is exceptionally effective in magnetic shielding. It is characterized by very high magnetic conductivity, allowing it to effectively "absorb" magnetic fields. As a result, it is widely used in various applications, from medicine to electronics.

Challenges in air transport

Moving magnetic separators calls for careful logistics, largely because of tight air transport regulations. Why is this critical? Uncontained magnetism could disrupt navigation systems, leading to a significant flight hazard.

To solve this employing specific packing techniques. We start by orient the magnets with alternating polarity - North against South - which naturally neutralize the magnetic emission. Crucially, we use steel sheeting as a shield. Thanks to its magnetic properties, meaning it absorbs the magnetic flux rather than allowing it to leak from the container.

Finally, documentation is key: carriers will refuse shipments that lacks a DGD declaration and proper shielding certification.

What documents does magnetic cargo have?

To ensure a smooth logistics process and compliance with global safety standards (like IATA DGR for air cargo), a complete set of documents is mandatory. Incorrect documentation is the #1 reason for shipment rejection at customs. Key requirements include:

• Dangerous Goods Declaration (DGD): The 'passport' for your cargo. It certifies that the shipment complies with regulations (e.g., IATA Packing Instruction 953) and poses no risk to navigation systems.
• Safety Data Sheet (SDS/MSDS): A detailed technical report on the material's chemical composition (NdFeB), physical properties, and emergency handling procedures.
• Packaging & Shielding Certificate: Verification that the package is properly shielded with steel plates and that the magnetic field outside the box does not exceed permissible limits.
• UN 2807 Labeling: Specific markings for 'Magnetized Material' to alert handling crews and pilots.

Evolution of knowledge about magnetism

Our understanding of magnetism has come a long way from the times when people believed that magnets possessed magical powers. Today, magnetism is one of the pillars of physics and is widely used in technology, medicine, and other scientific fields.

Beware of Magnets!

Managing and controlling magnets can be a challenge, mainly because it's not possible to completely block the magnetic field. The choice of the appropriate shielding material depends on specific needs. Often, steel proves to be an ideal solution, but in some cases, specialized materials such as MuMetal may be more suitable.