Simple attraction7 June 2000
A UK company has made several developments in the field of magnetic lifting
A new range of permanent magnet lifters for lifting ferrous material is promoted as ‘a revolution in the field of magnetic lifting’. Greatly improved portability is a primary benefit of the range, introduced earlier this year.
The Ultralift range from Eclipse Magnetics has a vast size and weight advantage over the previous EPL range. Each magnet in the new series is four times smaller than the corresponding magent in the old series. So the new 2t capacity UL2000 weighs just 91kg compared with the 300kg of the 2t capacity model in the old EPL series.
This has been achieved using a different magnetic material with a much higher power to weight ratio. Ultralift uses Neodymium iron boron which is a sintered material.
Five models are available, with lifting capacities from 250kg to 2t.
Correspondingly, unit weight is between 6kg and 91kg. List price of the UL2000 is nearly £600 ($900) less than the equivalent type it replaces, it has zero running costs and it is sealed for life which makes it maintenance free, according to the manufacturer.
A V-shaped groove in the base of the unit allows both flat and round sections to be lifted without the need for any adaptation. Magnetic lifters need less floor space than conventional slings and chains as access to the load is only needed from the top face, so loads can be stored closer together. Time is also saved as it is quicker to attach a magnet than it is to set slings or chains. There is also less risk of damage to surface coatings.
Eclipse Magnetics reckons it takes around £13m of the £16m UK market for lifting magnets, according to UK sales manager Tony Vargas. Despite the fact that some electromagnetic lifters have a variable depth of field to alter the amount of material or number of items that are picked up, manually operated permanent magnet lifters are more popular. Vargas says that manual versions are preferred because they are smaller, less setting up is needed, there are no trailing power cables and transferring lifters between cranes is easier. Battery operated electromagnets are also limited because time is needed for recharging.
All new Ultralift magnets come with the new Safety Shim, which – like all the best ideas – is so simple that it is amazing that no one has thought of it before. The Safety Shim (for which a patent is pending) is a simple metal plate, just a millimetre or two thick, which is used to test the safety of a lift. Quite simply, if the magnet picks up the load with the shim placed between the magnet and the load, you know that when the shim is taken out, the load can be lifted with the necessary 3:1 safety factor guaranteed.
It works regardless of whether the surface is uneven, rusty or otherwise coated. Nor is it necessary to know the weight of the load beforehand, or whether the material is an alloy or below the recommended thickness.
Lifting magnets have a known pull gap curve which shows how the holding power reduces as the air gap, or distance, between the magnet and the load increases. A magnet that can actually lift 6t in test loading is given a safe working load of 2t. Therefore it can lift 2t with the Safety Shim inserted. The shim must be removed for the actual lift to have the 3:1 safety factor. Forgetting to remove the shim after a successful test might be the only problem.