Lifting magnets are used in many areas, particularly where plate steel is handled, such as scrap yards, ship yards and steel workshops. They are used to lift and manoeuvre both flat and round steel in the horizontal position; however the steel must be ferro-magnetic to allow the powerful magnets within the lifting device to connect magnetically. Handling sheet metal with lifting magnets makes the task much easier.
What is a Lifting Magnet?
A lifting magnet or magnet lifter as they are sometimes referred to as is a piece of lifting equipment that is designed for lifting ferro-magnetic materials such as steel. Steel is produced from a mix of several metals, producing an alloy; the main ones being iron, nickel and manganese, these substances and their compounds are ferro- magnetic . However some types of stainless steel are not magnetic because of their make up. Metals with different make-ups have differing abilities to hold magnetism, so for materials other than mild steel (which this article mainly refers too) such as; high carbon steels, cast iron and ferrous alloys a reduction in the lifting capacity must be applied, this varies between the materials, so always refer to the lifting magnet manual.
A lifting magnet is a manual device and can be operated by a single person; they are able to create an extremely powerful magnetic field enabling it to grab the steel securely. However the steel must be clean and smooth for the optimum secure hold; if the steel is rough, dirty or badly machined, or even covered in paint or dust, then this can cause air gaps where the magnet will not hold, even if small these air gaps will have a significant effect on the magnetic force and so will be reduced.
Full contact with the steel surface is necessary, so for poor surfaces, air gaps and other factors; the lifting capacity will need to be reduced.
The thickness of the steel plate also needs to be thought about as some magnets have a minimum thickness that they can safely lift.
A lifting magnet is an easy device to operate, they are commonly used attached to a hoisting device; the magnet is simply placed onto the steel surface and the lever locked down, this creates the magnetic force. Don’t forget to ensure the magnet is placed about the centre of gravity to produce a balanced lift; more than one magnet lifter may be used together for larger materials. Permanent magnets, battery magnets and hand held magnetic grabs / claws are all available from Lifting Gear Direct.
The Contact Area for Lifting Magnets:
The full lifting capacity of the lifting magnet can only be accomplished if the magnet makes full and total contact with the load being lifted, If the contact surface (i.e. sheet steel) has holes in or maybe has an uneven, distorted or rough surface then the performance will be affected accordingly.
You should always carry out a trial lift, (slightly raised) in these circumstances to confirm that the load is safe and correct prior to completing the transport of the load to its intended destination.
The high magnetic forces that are produced by the TPM permit the magnet to clamp components throughout the air gap, nevertheless air gaps will reduce the magnetic performance since they supply a barrier amid the contact surfaces.
Air gaps can occur in various ways such as paint, dust, and heavy mill scale; surfaces which have not been machined very well can also constitute an air gap. You should down rate the magnets capacity accordingly, as recommended.
Using a Lifting Magnet Safely.
As with all lifting devices, safety is imperative, so here are some basic tips for ensuring optimum safety whilst using a lifting magnet.
- Ensure the crane or hoist’s hook is suitable for the magnet and the SWL is appropriate.
- A load suspended with a lifting magnet should not be left unattended for long.
- Test / trial lifts should always be carried out to ensure the hold is secure.
- When more than one lifting magnets are used together to lift larger objects then a spreader beam should be used for stability.
- Ensure the surface of the steel is in good condition to prevent air gaps.
- Never lift or move loads whilst people are in the area of movement.
- Never magnetize the magnet lifter (by locking the handle down) without a load.
- Never de-magnetize the device (by raising the handle) until the load has been completely set down.
- If lifting round objects like pipes the lifting capacity will be reduced as full contact will not be made.
- NEVER use a magnet lifter around medical equipment, pacemakers and/or insulin pumps, as the magnetic force can cause the equipment to fail.
A lifting magnet should be inspected and serviced at least every 12 months to confirm its safety for use, however a visual check should be made by the operator prior to each use checking for any issues which may affect its performance, things such as cracked housing, broken handles, damaged suspension eyes should be looked for and it should be clean and clear of dust and debris.
Browse our full selection of lifting magents below for full technical details and call our team on 01384 76961 to discuss any requirements.