SmCo Magnet Air Freight Compliance and Shielding Packaging Guide (IATA 953)

When procurement teams issue a Purchase Order for Samarium Cobalt (SmCo) magnets, the focus is overwhelmingly on magnetic properties, dimensional tolerances, and high-temperature performance. Logistics is often treated as an afterthought—a simple line item marked "Air Freight (FCA/DAP)."

However, because of the extreme magnetic strength of SmCo alloys, shipping these materials by air is strictly regulated. If a shipment arrives at the origin airport without adequate magnetic shielding or proper documentation, it will be flagged by airline safety inspectors, resulting in immediate rejection, indefinite customs holds, and severe supply chain delays.

This guide provides purchasing managers, logistics coordinators, and engineering teams with a clear framework for navigating the IATA Dangerous Goods Regulations (DGR) Packing Instruction (PI) 953. We cover the exact classification thresholds, the engineering behind magnetic shielding, the hidden impact on volumetric freight costs, and the verification checklists you must enforce with your supplier before a shipment ever leaves the factory.

The Aviation Risk: Why Magnets are Regulated

Commercial aircraft rely on highly sensitive navigation equipment, particularly magnetic compasses and automated flight control sensors. A stray magnetic field emanating from the cargo hold can interfere with these critical instruments, causing compass deviation and navigational errors.

Standard ferrite magnets or small, low-grade Neodymium magnets rarely possess a magnetic field strong enough to penetrate commercial cargo containers and reach the flight deck. However, Samarium Cobalt (SmCo5 and Sm2Co17) and high-grade Neodymium (NdFeB) magnets are entirely different. A single high-performance Sm2Co17 block magnet can project a measurable magnetic field several meters away. When hundreds or thousands of these magnets are packed into a single pallet, the cumulative magnetic flux can easily breach the walls of standard packaging, presenting a severe risk to aviation safety.

To mitigate this, the International Air Transport Association (IATA) developed strict guidelines classifying highly magnetic materials as Dangerous Goods, explicitly regulating how they must be tested, shielded, and declared.

Understanding IATA PI 953: The Testing Distances

IATA PI 953 defines the acceptability of magnetized materials for air transport based on magnetic field strength or compass deflection measured from the outer surface of the fully prepared package. The testing must be performed using a calibrated gauss meter or a precise magnetic compass, and the buyer should request a report showing measurement distance, maximum reading or deflection, test device, and calibration date.

1. The 4.6 Meter (15 Foot) Threshold

At a distance of 4.6 meters (15 feet) from any point on the surface of the packaged shipment, the magnetic field strength must not exceed 0.418 A/m (0.00525 gauss), or produce a compass deflection of more than 2 degrees.

• If the package exceeds this limit: It is strictly prohibited from air transport under standard conditions. It cannot be flown on passenger or standard cargo aircraft. The shipment must either be re-packed with thicker shielding, split into smaller batches, or shipped via sea freight.

2. The 2.1 Meter (7 Foot) Threshold

At a distance of 2.1 meters (7 feet) from any point on the surface of the packaged shipment, the key question is whether the package still causes more than 2 degrees of compass deflection. DG test references often express the "not restricted" floor as below 0.159 A/m (0.002 gauss) at 2.1m. Do not apply the 4.6m acceptance ceiling of 0.418 A/m (0.00525 gauss) as if it were the 2.1m "not restricted" threshold.

• If the package causes more than 2 degrees of compass deflection at 2.1m, BUT passes the 4.6m test: The shipment is treated as UN 2807 - Magnetized Material under PI 953 controls. It can be shipped by air, but it requires prior arrangement with the operator, a magnetized material handling label, and air waybill or transport-document wording. A Shipper's Declaration is generally not required for UN 2807 alone when the required wording is shown, but carrier surcharges and pre-approval can still apply.
• If the package causes no more than 2 degrees of compass deflection at 2.1m: The shipment is typically considered Not Restricted as magnetized material. It can be shipped as general cargo without Class 9 magnetic material controls, though a supplier test report is still highly recommended to prevent airline delays.

The IATA 953 Classification Workflow

Magnetic Shielding Engineering: How Suppliers Pack SmCo

To ensure a shipment of SmCo magnets passes the 2.1m "Not Restricted" test, suppliers must employ specific magnetic shielding techniques. You cannot simply place SmCo magnets into a standard cardboard box and hand it to FedEx or DHL. The magnetic flux will easily penetrate standard materials like wood, plastic, and corrugated cardboard.

Proper magnetic shielding relies on two primary principles: Flux Routing and Distance.

1. Flux Routing (High-Permeability Materials)

To prevent the magnetic field from radiating outward, the supplier lines the inner walls of the shipping carton with a high-permeability material—most commonly thick iron or mild steel plates. High-permeability materials provide a path of least resistance for the magnetic field. Instead of traveling outward into the air, the magnetic flux lines are "captured" and routed through the steel plates, creating a closed magnetic circuit within the box.

Depending on the cumulative strength of the shipment, the iron sheets may need to be 1mm to 3mm thick. If the shipment is exceptionally strong, multiple layers of iron shielding may be required.

2. Distance (Cushioning)

Magnetic field strength drops exponentially as distance increases (following the inverse cube law). By placing the magnets in the absolute center of a large box and filling the remaining space with rigid foam (EPS or EPE), the supplier artificially increases the distance between the magnet surface and the outside of the package. This is a highly effective, low-weight method for reducing the field strength at the package surface, though it significantly increases the overall volume.

3. Pole Neutralization

Before packing, experienced suppliers will arrange the SmCo magnets so that their polarities oppose one another (North to South, South to North). This causes the individual magnetic fields to cancel each other out to a significant degree, drastically reducing the net magnetic field of the entire block before shielding is even applied.

The Hidden Cost: Shielding, Volumetric Weight, and Freight Economics

When purchasing SmCo magnets from overseas, procurement teams often miscalculate the freight cost because they base their estimates strictly on the net weight of the magnets. They fail to account for the massive impact of magnetic shielding.

Air freight charges are calculated based on Chargeable Weight, which is the greater of the Actual Gross Weight or the Volumetric (Dimensional) Weight.

• Actual Gross Weight Increase: The iron plates used for magnetic shielding are incredibly dense. A standard 400x300x300mm carton lined with 2mm thick steel plates can easily add 10 to 15 kg of pure dead weight to your shipment.
• Volumetric Weight Increase: To utilize the "distance" shielding method, suppliers must use excessively large outer cartons filled with lightweight foam. IATA volumetric weight is calculated as (Length × Width × Height in cm) / 5000 or 6000 depending on the courier. A box that is 80% foam will have a volumetric weight far exceeding its actual weight.

Economic Reality: If you purchase 20 kg of SmCo magnets, the final packed shipment with iron shielding and foam spacing will likely result in a chargeable weight of 45 kg to 60 kg. When budgeting for your SmCo programs, you must mandate that your supplier provides a Chargeable Weight Estimate inclusive of IATA 953 shielding during the RFQ phase, not just the net weight of the goods.

Packaging Acceptance Checklist for Buyers

To prevent your shipment from being impounded at the origin airport, mandate the following requirements on your Purchase Order. This structural checklist ensures the supplier is liable for compliance before the goods are handed to the freight forwarder.

Do not assume a supplier knows how to ship magnets simply because they manufacture them. Manufacturing and logistics compliance are entirely separate skill sets.

When to Transition to Sea Freight

For prototype runs, pilot builds, and urgent replacement parts, air freight is unavoidable. However, as your SmCo program transitions into mass production, the economics of air freight quickly deteriorate due to the shielding requirements.

The Break-Even Point: As a general rule of thumb, once your continuous order volume exceeds 150 kg to 200 kg of net magnet weight per month, the cost of iron shielding and air freight surcharges makes sea freight highly attractive.

Sea freight (LCL or FCL) is not subject to IATA PI 953. While magnets still need basic protection for handling, the stringent 2.1m and 4.6m compass deflection tests do not apply. This allows the supplier to pack the magnets much more densely, eliminating the cost of heavy iron plates and bulky foam distance-packaging. The savings on the freight rate and the packaging materials will often offset the cost of holding an additional 4 weeks of inventory buffer.

Internal Engineering Alignment

Procurement teams must align with engineering regarding the state of the magnets at the time of shipping.

• Unmagnetized Shipping: Can the SmCo magnets be shipped in an unmagnetized state and magnetized at your facility (post-assembly)? If yes, the entire IATA PI 953 regulation is bypassed. Unmagnetized SmCo poses zero aviation risk and requires zero iron shielding. However, magnetizing Sm2Co17 post-assembly requires massive energy pulses (often >35,000 Oersted) and specialized magnetizing coils that many OEMs do not possess.
• Assembled Shipping: Shipping a fully assembled rotor with SmCo magnets already glued and secured is often easier to shield than shipping loose magnets, as the steel rotor hub acts as a natural magnetic return path, containing much of the flux.

Frequently Asked Questions (FAQ)

What happens if my supplier ships strong SmCo magnets by air without shielding?

If the shipment bypasses origin screening and causes compass deviation on the aircraft, it is a severe aviation safety violation. The airline will investigate the airway bill, and both the supplier and the importer of record can face heavy fines, loss of shipping privileges, and potential legal action from the aviation authority (such as the FAA or EASA).

Do courier services like DHL, FedEx, and UPS accept SmCo magnets?

Yes, but they are incredibly strict. They typically require a third-party magnetic test report (such as a DGM certificate) proving the fully packed shipment meets the current "Not Restricted" criteria at 2.1m before they will even pick up the box from the factory.

Why is my supplier asking for an extra fee for "Magnetic Inspection"?

At major export hubs in China (such as Shanghai Pudong or Shenzhen Bao'an), airports mandate that an independent, certified testing laboratory conducts the magnetic field test before the goods are allowed into the cargo terminal. This fee (usually around $10 to $30 per shipment) is legitimate and unavoidable for air freight.

Does the iron shielding affect the magnets inside?

No. The iron sheets used for the outer packaging do not degrade or alter the permanent magnetic properties of the SmCo magnets inside. The shielding merely redirects the ambient field. Once unpacked, the magnets will operate exactly to specification.

We are buying SmCo5 instead of Sm2Co17. Does IATA 953 still apply?

Yes. While SmCo5 has a slightly lower Maximum Energy Product than high-end Sm2Co17, it is still an incredibly powerful rare earth magnet. Any bulk shipment of SmCo5 will easily violate the 2.1m threshold if not properly shielded.

Closing Recommendations for OEMs

Shipping Samarium Cobalt by air is an exercise in balancing urgency with compliance. If your project requires urgent delivery, you must accept the financial penalty of iron shielding and volumetric weight multipliers. To maintain control over your supply chain:

1. Demand transparency on chargeable weight during the RFQ stage.
2. Mandate IATA PI 953 test reports as a condition of final payment.
3. Transition to sea freight as early in the production lifecycle as your inventory buffers allow.

For further insights on managing SmCo supply chain risks, review our guides on Incoming Inspection Checklists for OEMs, End-Use Certificate Compliance, and SmCo Cost Drivers.

To discuss your specific SmCo magnet requirements, packaging constraints, or to request a fully landed freight estimate, contact our engineering team via RFQ.

Field Evidence Snapshot

• Air-shipment delays usually happen after final packaging, when the closed carton or pallet is measured and the actual field exceeds the booking assumption.
• RFQs should request package-level magnetic test data, shielding photos, gross weight, volumetric weight, and carrier pre-alert evidence before goods leave the factory.
• Buyers should treat "not restricted" as a measured shipment condition, not a material property of SmCo magnets alone.

Related Internal Guides

• SmCo Incoming Inspection Checklist for OEMs
• SmCo End-Use Certificate and Export Compliance
• SmCo Magnet Cost Drivers and Tolerance Yields
• SmCo RFQ Checklist for OEM Buyers

External Standards and References

• IATA Dangerous Goods Regulations (DGR)
• FAA PackSafe - Magnets
• 49 CFR 173.21 - Forbidden materials and packages
• DGM New York - Shipping Magnetized Material by Air (UN 2807)

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Disclaimer: This guide is for informational purposes only. Aviation safety regulations are subject to change. Always consult the most current version of the IATA Dangerous Goods Regulations (DGR) or a certified Dangerous Goods Safety Advisor (DGSA) before shipping magnetic materials.