Magnetic lifters are a lightweight and cost-effective way of transporting heavy materials in situations where another method of material handling would be difficult, dangerous, or expensive.
These lifters use magnets to hold heavy materials securely without requiring clamps, slings and other holding equipment. They are most beneficial in situations in which another method of material handling would be difficult, dangerous, or expensive.
Lifting magnets vary widely in size. Usually, the larger ones are hung from a chain on a crane that is able to move the lifting magnet into the location necessary to retrieve the material. This type of lifter can be used for a wide variety of purposes, including automobile junking, construction, and demolition and cleanup.
How Lifting Magnets Work
There are two types of lifting magnets: permanent magnets and electromagnets. Permanent magnets use permanently magnetized material to create a magnetic field. They can be used to lift loads up to 2,200 pounds. These lifters can be moved easily to various work locations. However, one disadvantage of permanent magnets is that they have a restricted lifting capacity. If a variable lifting capacity is required, the optimum choice is the electromagnetic lifter.
Electromagnetic lifters use an energized electrical coil wound around a steel core to orient magnetic domains within ferrous materials in a common direction, thus, creating a magnetic field. Unlike permanent magnets, electromagnets require a constant DC power source. Hence, a power failure can be a safety issue with electromagnets unless an emergency power or backup supply is integrated with this type of lifting system.
Permanent magnets are favored (1) when electricity is not available, (2) when power failures are a common occurrence, or (3) when adjustable magnetic force is not necessary. Electromagnets are the choice for applications where varying strength or remote magnet control is required.
Suitable Applications for Lifting Magnets
Smooth, Flat Surfaces: Permanent lifting magnets are manually operated. They create a very strong but low magnetic field so they are sensitive to air gaps between the magnet and the load. When an air gap increases, the magnetic force will be significantly reduced. They work best on smooth, flat surfaces rather than rough and irregular ones.
Type of Material: While ferromagnetic materials are inherently magnetize-able, paramagnetic materials, such as aluminum and magnesium are not. (Diamagnetic materials, such as copper, lead, and silver, do not magnetize.) For materials other than iron-based materials, a reduction factor must be calculated to determine the effective holding force.
Thickness of Material: The thickness of the material to be lifted also plays a role factor in selecting a lifting magnet. Thick materials are the best candidates. Materials thinner than the specification for the lifting magnet will have a much lower level of holding force.
Benefits
Lifting magnets save time by reducing and sometimes eliminating blocking and slinging. They can also eliminate or decrease waste. They reduce product damage commonly caused by chains, hooks, and other mechanical grabs. But the significant advantages of lifting magnets are ease of operation and cost-effectiveness.
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