What to Check Before Using a Magnetic Lifter

A permanent magnetic lifter is simple to use. Set it on the load, turn the handle, and lift. The hold depends on the load as much as on the lifter, so a few checks are needed before every lift.

This guide lists them in order.

1. Is the load within the rating?

Every lifter has a safe working load for a flat plate of low carbon steel, at a given minimum thickness, with a clean flat surface. This is the flat rating. A round bar touches the base along a single line, so the round rating is half the flat rating.

Know the weight of the load. If you are not sure, work it out from the size. A steel plate weighs about 7.85 kg for every square metre of area per millimetre of thickness.

2. Is the plate thick enough?

The magnetic field passes into the load. A thin plate cannot carry the whole field, and some of it passes through to the other side. The hold is weaker. Each SMAG Maxx model has a minimum job thickness, from 15 mm on the smallest to 100 mm on the largest. Below that thickness, the rated load is reduced.

3. Is the contact surface clean and flat?

The hold falls quickly with any gap between the base and the load. Rust, scale, paint, oil, swarf and a rough surface all count as a gap. Clean the contact area before the lift. A machined or ground surface gives the full rating.

4. What is the load made of?

Low carbon steel gives the full rating. Other materials hold less:

• Medium carbon and alloy steels hold a little less.
• Cast iron holds roughly half.
• Hardened steel holds less than soft steel of the same grade.
• Austenitic stainless steel, aluminium, copper and brass are not held at all.

5. How hot is the load?

Heat weakens the magnets. Keep the load below 80 degrees Celsius. Do not lift material straight from a furnace or a hot cutting process.

6. Is the load one piece?

Lift one plate at a time. Two stacked plates may seem to lift together, then separate in the air. Long thin plates may sag at the ends and peel away from the base. Place the lifter over the centre of gravity.

7. Is the lifter in good condition?

Look at the base. It should be clean, flat and free of dents and swarf. Check that the handle turns fully and locks in the on position. Check the shackle and the crane hook.

8. Test the lift

Raise the load a few centimetres. Pause. Check that the load is level and holding. Then move it, keeping it low and clear of people.

After the lift

Set the load down fully before turning the handle off. Turn the handle to the off position and lift the lifter clear. Never leave the lifter switched on with no load. Store it on a wooden or non-magnetic surface.

The SMAG range

Santosh Magnetic Works makes the Maxx series of permanent magnetic lifters in twelve sizes from 100 kg to 6,000 kg. Every lifter is tested to three times its safe working load before dispatch. See the range or contact us.