An electromagnetic crane is a type of crane with an electromagnetic lift. Electromagnetic cranes are commonly utilized in lifting and moving various scrap metals. It does not have the mechanical 'pincers' of a regular crane, instead, it has a large flat magnet which draws the metallic materials to it. Using the principle of electromagnetic induction, these large machines are used to handle scrap ferrous metals, such as iron and steel, which can be found in junk yards and recycling plants. Beyond the area of lifting magnetic materials, another use of an electromagnetic crane is that it makes for smooth and safe stops due to its solenoid brakes (electrically controlled brakes which can be turned on and off by a solenoid). These brakes are the ones being used on movable bridges as it allows the passage of boats and barges.
How The Electromagnetic Crane Works: An electromagnet is a type of magnet wherein the magnetic field is produced by electric current, and the field disappears whenever the current is turned off. Electromagnets are being utilized in everyday items, just like loudspeakers and doorbells. An electromagnetic crane has a large electromagnet which can be turned on and off. The electromagnet contains an iron core with a wire around it, and this wire is the medium by which the current travels. The magnetic strength of an electromagnet relies on the number of turns of the wire around the electromagnet's core, the current through the wire and the size of the iron core. Increasing these elements will result in an electormagnet which is significantly larger and stronger as compared to a natural magnet (which explains the enormous size of the crane's magnet). For the electromagnet to be turned off, the core must be made of soft iron. Therefore, turning on the electricity will enable the magnet to work, and turning off the electricity will be able to shut it down.
Dismantling the old crane Over the past years, the existing cranes at voestalpine Rotec GmbH in Krieglach have been successively replaced with new and modern cranes. The magnet crane in the pickling plant which dates back to 1967 has recently been exchanged.
Magnet crane with four electromagnets The new magnet crane with magnets The new magnet crane hoists loads using four electromagnets attached to two mobile spreaders. This has the following advantages: ideal positioning of the magnets on the bundles of tubes
better coupling of the magnetic force, and therefore a significant increase in safety.
The new crane also has more lifting power and height, and is easier to operate. A further crane is scheduled for replacement this year.
Technical data for the new magnet crane:
Breadth: 21 m
Hoisting unit: 10.3 tons
Lifting power on the magnet spreader: 4.8 tons
Lift height: 6.2 m
New category 2 electronic safety control system
Lifiting Battery Magnet Safebat: The Safebat 10 is the first electropermanent battery lifting magnet showing the operator on the display which load can be lifted safely during the lifting operation. The power electronics calculated this data within seconds and automatically while putting the magnet on the work piece. Sheets from 4 mm thickness can also be lifted off the stack individually Even magnetizing and demagnetizing of the electropermanent battery magnetcan take place
automatically. Application: - For flat and round material, as the adhesive surface is provided with a prism pole shoe. - Usable for traverse operation with several magnets - For thin and thick, small and large sheets - also for multi-shift operation - For raw material, semi-finished and finished products - In mechanical engineering, tool manufacturing, plant engineering, steel construction, shipbuilding, steel mill, cutting-, laser operation, transport company or materials store Professional advantages: - Via the pick-up mechanism, the Safebat can be switched without pushing a button - The operator can see the safe lifting power on the display - No current flows during lifting (only a pulse current for a few seconds is required for magnetizing or demagnetizing) - Current load display indication: the magnetic flow is currently calculated based on the material, work piece thickness and air gap, with the safe lifting force being shown within a few seconds on the display during uplift Options: - Special pole shoe for individual applications - Services: Test according to German Accident Prevention Regulations and repair
Used for scrap handling, billet handling in steel industries
Why Lifting Magnets Are Attractive Compared to slings and chains, they save time and protect the part. Here are some of the basics of magnetic lifters. Magnetic lifters are versatile work handling devices that can be used to move a variety of ferrous metals ranging from small bundles of rod or scrap to large, heavy blocks. When used to replace slings and chains, lifting magnets can improve overall productivity by allowing a single person to lift a load that may have required two or more people the old way. The trick is to move the load safely, and to do that the equipment needs to be properly specified and applied. Magnetic lifters offer advantages related to both quality and labor. For example, magnets eliminate the need for drilling and tapping holes in parts so that eyebolts can be attached to move them. In many cases, these holes need to be filled and the surface needs to be refinished, adding cost to the product. An example of how a magnetic lift can positively impact productivity might involve a crate of parts that require machining. Often the parts are situated in such a package side by side, to use all of the area in the container. If the parts are located so that the operator can only access the parts from above, a lifting magnet can be applied to a single part, lifting it vertically out of the container. Assuming the container is filled with round shafts packaged horizontally, using a strap or chain in place of a magnetic lifter would require one end of the part to be lifted
manually so that the strap or chain could be passed underneath—just to lift a single bar. A lifting magnet could be lowered from the crane above, attached to the desired piece and lifted out of the container with minimal effort. Magnets further save time by eliminating blocking and slinging. They also reduce waste. Because magnets won't mar metal surfaces, they decrease the potential for the kind of product damage often caused by chains, hooks and other mechanical grabs. Types Of Lifting Magnets
There are two basic types of lifting magnets: permanent magnets and electromagnets. Permanent magnets are exactly that—permanent. These magnets use permanently magnetized material to build up the magnetic field. Permanent magnets used in work sites generally turn on and off by means of a lever. They can be used to handle flat materials, as well as round parts weighing up to 2,200 pounds. These kinds of lifters are self-contained and can be moved without difficulty to various work sites within machine shops. However, one disadvantage is that permanent magnets have a restricted lifting capacity. Electromagnets employ electricity to charge the magnet and hold the material to the magnet face. Electromagnets use an energized electrical coil wrapped around a steel core to orient particles within ferrous materials in a common direction, thus creating a magnetic field. Electromagnets are generally built to run on DC current, creating the need for a rectifier. Unlike permanent magnets, electromagnets require a constant power source.
This can be viewed as either a detriment or an advantage, depending upon how the magnet is being used. A power failure can be catastrophic when using an electromagnet— though universal power supplies and battery backup systems available in today's market address these concerns. On the other hand, the ability to vary the current being supplied to the magnet allows the user more flexibility than a permanent magnet affords. Permanent Vs. Electromagnets
Both permanent magnets and electromagnets can be constructed to produce different types of magnetic fields. The first consideration in choosing a magnetic circuit is the job you want the magnet to do. Permanent magnets are favored when electricity is not readily available, when power failures are a common occurrence or when adjustable magnetic force is not necessary. Electromagnets are useful for applications where varying strength is required or remote controlling is desired. Magnets should be used only in the manner for which they were originally intended. Using the wrong type of magnet for a specific application can be extremely dangerous and possibly even deadly. Many machining operations are performed on thick, blockshaped material. These applications call for permanent magnets. Many machine shop users believe the greatest advantage of these magnets is the lack of an electrical hookup or a recharging requirement. Permanent magnets feature capacities ranging from 330 pounds to 10,000 pounds. These magnets are easily turned on and off by simply rotating a lever. A safety latch is typically built in to ensure that the magnet is not
accidentally turned off while performing a lift. Multiple magnets can be used for heavier loads that are too long for a single unit to handle. Still, there are times when the part to be machined is thin —0.25 inch or thinner—and the part is presented to the machine operator as one of a stack of similar parts. Permanent magnets are not designed to lift only one piece from the stack at a time. Permanent magnets, while extremely reliable when properly applied, are not able to alter the amount of magnetism produced. In this case, an electromagnet with variable voltage control allows the operator to manage the magnetic strength and select only one piece from the stack. Self-contained electromagnets are the most cost-effective magnets per pound of lift. Capacities can extend up to 10,500 pounds. Reducing costs of equipment and operation, self-contained electromagnets operate on 115-volt AC power. Battery-powered magnets are available. They use a selfcontained gel cell-type battery to expand the lifting capacity, and they allow handling of flat products, rounds and structural shapes. Battery-powered magnets can be moved from hoist to hoist, offering generous lifting capacity without an external power connection. They do require periodic recharging.
Getting Started With Magnetic Lifters
Lifting magnets, whether electric or permanent, all have a rated capacity listed on the nameplate. This capacity relates to a particular thickness. If the magnet is being
used on a material that is thinner than the material it was rated on, the capacity will be reduced. Lifting magnets may be used in multiples on beams to augment the amount capable of being lifted. When multiple magnets are used to lift loads, the magnets should be spaced evenly to carry the whole load. Materials have a tendency to sag when unsupported, so magnets should be sized properly to support the load. When loads are being lifted and rotated to a shear position, it should be noted that the magnet's capacity drops to about one-fourth of what the nameplate states. Additionally, materials tend to slide when subjected to shear forces. Therefore, much care should be taken in these applications. Larger magnets present on overhead cranes are dedicated to the crane mechanism and its range of movement. Multiple magnet mounts give overhead cranes a lifting capacity limited only by the crane itself. The fundamental components of these systems include the magnet or magnets suspended from the crane hook(s), and a spread beam if necessary. Given that magnets operate on DC, a combination AC to DC rectifier and magnet controller is mounted on the crane. This device converts the crane power from AC to DC and turns the magnet on and off. Remotely operated lifting magnets can be cab controlled, or they can be controlled through a pendant switch or a remote control transmitter. These systems are used to deal with single or multiple plate, whether in storage areas, loading or unloading of trucks, or loading and unloading of cutting tables.
A trained professional must install the magnet. The supplier will usually send out personnel to evaluate the application and handle the installation process. Electromagnets require greater setup time and additional equipment because of the DC electrical connection. Electromagnets are also outfitted with battery backups in case of power failure.
The advantage would only be in scrap yards involving the electro-magnetic handling of ferrous-metals. unfortunately stainless steel is non-magnetic there are electric cranes which run on bridge-like structures but these are not electro-magnetic these have some tactical advantages of very precise control, solenoid brakes which are electro -magnetic, and safety and low noise also they do not pollute. These are normally used indoors in factories and warehouses. They usually have (dead man) controls which revert to neutral or stop if the operator lets go they spring back to the central position again aiding safety. Disadvantages are as follows: They only attract ferrous (Iron containing) metals and not even all of them.
Stainless Steel is Non-magnetic, it thus can be used on compass housings (like the Sperry Iron Mike) but is not attracted to magnetic fields. It is not possible to fine-tune the electromagnet to adjust for this. This would be useful in recycling beverage cans, which are nearly all Aluminum. Though some food cans have steel tops as they work with magnetic can openers. This is common with Cat Food. By the way Crane Magnets ONLY function normally on DC.
Applications:
It helps in lifting quite heavy objects. It starts it properties of attraction and repulsion on our command. It is usually used in garbage dumps as helps in lifting garbages. It helps in separating the steel and iron materials from the garbage.
Control
Even the strongest natural magnet cannot lift a heavy steel object, such as an automobile, but industrial electromagnets can. Another advantage of electromagnets is that the magnetic force can be controlled by switching the current that flows through it on or off.
Huge, strong electromagnets are employed in heavy industrial cranes, such as those in salvage yards, to lift, move and drop heavy iron or steel objects. These electromagnets are typically contained in a heavy cage or machined steel casing, insulated from the copper or aluminum windings inside.
Lifting
Braking
In addition to their lifting capability, electromagnets are also employed in the braking systems of certain types of heavy-duty cranes. These are typically coupled at the rear of the crane motor, together with a fan that ensures air circulation.
