The workpiece determines capacity
Not all steels respond equally to a magnetic field. Thickness, stiffness, shape and effective contact area must match the conditions for which the device was selected. A thin plate can behave differently from a solid block of the same mass.
The complete arrangement of Slings and lifting accessories also includes connections and the carrying machine. Magnet self-weight, orientation and the load’s centre of gravity must be considered. Its connection needs to accommodate the intended position without being forced against the hook.
Do not improvise at the contact surface
Rust, paint, dirt or a protective layer can separate the magnet from the material and reduce holding force. A covering must not be added to prevent surface marks unless the manufacturer has allowed for it in the application.
IMCA reported a dropped load after one protective layer was replaced by a thicker material. The task had previously been completed without incidents. The lesson is to assess the physical change and document the method rather than treat previous successful lifts as proof of safety.
Anticipate loss of retention
Permanent, electromagnetic and electropermanent lifters behave differently during power failure. Safeguards, warnings and backup arrangements must suit the design and application. None of these technologies removes every other cause of a load becoming detached.
Lifting stacked pieces or bundles needs specific assessment. Holding the upper piece does not demonstrate that those beneath it are secure. Transport banding is not automatically a rated means of lifting the whole bundle, and its appearance gives no reliable assurance of lifting capacity.
Protect the surrounding area
Travel and landing areas must prevent people reaching beneath the load or entering its potential fall zone. Possible interaction of magnetic fields with medical implants and control systems also needs assessment using technical information and specialist advice.
Inspections cover the contact face, suspension, wiring, controls and backup systems where fitted. Training should explain material limitations and responses to faults. These principles do not replace manufacturer capacity tables or authorise improvised load testing, and the site’s applicable inspection requirements must still be followed.
