Benefits |
Universality: EM can generate a very deep magnetic field making them suitable for many different applications, including situations where contact between magnet pole shoes and load or the different elements constituting the load is limited with significant spaces (air-gaps). Typical examples are ferrous scrap or bundle applications where the bundle is made of many structural pieces. Flexibility: Easy to partialize the force of the magnet by partializing the voltage or current provided to the magnet. Suitable for hot applications, up to 650°C (1,200°F). |
Limits |
Need for Battery back-up: The lifting force of an EM depends on continuous electrical feeding which, when safety is a sensitive factor, requires a battery back-up system to cover possible electrical power (main) interruptions as well as suitable protection and maintenance of the power cables to prevent possible accidental interruption. |
Benefits |
Safety: The lifting force of an EPR is exclusively based on the intrinsic force of its permanent magnets and is independent from any external source of energy. The load does not drop in case of accidental power failure or cable interruption. No battery back-up needed. Duty cycle. After activation through a short current impulse, the EPRs do not generate heat which means that their lifting force remains constant and independent from duty cycle (except for hot material applications). |
Limits |
Shallow magnetic field: EPRs generate a shallower magnetic field than EMs which means that they are suitable for applications where contact between magnet pole shoes and load presents limited air gaps. Temperature. Standard EPRs can be used for hot material applications up to 250°C (480 °F)and special EPRs can work for material applications up to 450°C (840°F). |
Application |
EM |
EPR |
|
---|---|---|---|
Ferrous scrap | x | ||
Slabs | x | x | |
Billets | x | x | |
Coils, eye horizontal | Hot rolled | x | |
Cold Rolled | x | x | |
Coils, eye vertical, annealing bay | x | x | |
Wire coils, eye horizontal or vertical | x | ||
Rails | Single, layers | x | x |
Bundles | x | ||
Single beams | x | x | |
Bundles of structurals, rebars,… | x | ||
Plates | Single | x | x |
Multiple | x | ||
Pipes | Single, layers | x | x |
Bundles | x |
When both the EM and EPR technologies can be used for an application, the recommendation for one technology versus the other depends on the possible limitation of material temperature and on the safety level requirement of the application. Moving slabs in a slab yard is not as critical, from a safety point of view, as loading or unloading slabs into or from a vessels in a port. EPR technology is particularly suitable for remote operation because force is constant and duty cycle is not an issue.
For hot applications and intensive duty cycle ones, typically at the exit of a caster , SGM disposes of a proprietary magnet called Convection Electro Lifting Magnet which, thanks to its special design for heat dissipation, drastically extends its duty cycle and life time.