How to Choose & Use Lifting Magnets
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Page 1.INTRODUCTION 2.CONSTRUCTION OF LIFTING MAGNETS 3.WEIGHT, SHAPE AND AREA OF LOAD 4.SURFACE CONDITION OF LOAD AND MAGNET 5.STIFFNESS OR FLEXIBILITY OF LOAD 6.SIZES AND SHAPES TO BE LIFTED 7.VARYING LOAD SIZES AND SHAPES 8.PARTIAL MAGNET FACE USE FOR LIFT 9.LIFTING MAGNETS WITH SPECIAL SAFETY FEATURES 10.SAFETY FACTOR 11.NUMBER OF LIFT MAGNETS FOR MAXIMUM EFFICIENCY 12.LIFTING LOADS WITH UNDEFINED SHAPES 13.AUXILIARY POLE PLATES 14.DROP CONTROLLERS 15.TYPICAL APPLICATION EXAMPLES - AUXILIARY POLES 16.TYPICAL APPLICATION EXAMPLES - LIFTING COILS 17.TYPICAL APPLICATION EXAMPLES - LIFTING...

Lifting magnets may be electro or permanent, and may be installed and used assingle magnets or as arrangements of multiple magnets. In all of these cases, making an optimum selection of lifting magnet components to handle steel plate and shapes requires a thorough knowledge of the application.The factors that dominate the lifting magnet selection for any specificapplication are:1. Weight, shape, and contact area of the objects to be lifted.2. Surface conditions of load and magnet. 3. Stiffness of load. 4. Range of sizes and shapes to be lifted. 5. Frequency of occurrence of the different...

CONSTRUCTION OF LIFTING MAGNETS Did you know? All electromagnets use DC power. In applications whereAC power is preferred, a rectifier is needed to convert ACpower to DC. Accordingly, it is possible to operateelectromagnets from a DC battery source. Lifting magnets fall into two general shapeclassifications: round and rectangular.The round lifting magnet is built with a centerpole (or core) and a round outer pole concentric with the center pole. This magnet can be either permanent or electro.The round electro lifting magnet is most efficientwhen considering its face area as related to lift...

But if the same load offers a much larger contact area magnets of a differenttype, or smaller magnets of the same type, but more of them, can be used. These smaller magnets need not produce a field with such deep penetration into the load because the power of each magnet can be multiplied by the number used. Did you know? The number of poles a magnet has is determined by itsintended use. As a general rule of thumb, the more polesӔon the face of the magnet, the shallower the magnetic field.A two-pole magnet typically has a deeper field (extendingfarther from the face) than a magnet with 3 or...

Did you know? Anything that prevents the face of the magnet frommaking full contact with the part being lifted is consideredan air gapӔ. Rust, dirt, ice, snow, machine grooves andholes are just a few examples of an air gapӔ. It isreccommended the magnet make full contact with acleanӔ part before lifting. For holding or lifting magnet applications we are concerned with distancesbetween magnet and load measured in fractions of inches (or only a few millimeters). These distances are very small in comparison to the dimensions of the magnetic poles and loads themselves. Also, we are frequently...

SIZES AND SHAPES TO BE LIFTED For practical reasons most lift-beam andmagnet assemblies are used on a wide range of load sizes. This is particularly true when the assembly is used to unload or load flatcars or trucks where the load can be plates of varying sizes at one time and bars or beams or other structural shapes at another. The assembly must be designed with the proper selection and arrangement of magnets so that it is efficient on the full- range of items handled. If, for example, amagnet and lift-beam assembly is used to unload plates that vary in size from 12' x 8' (3658mm x...

EXAMPLE: 4' x 8' x 1" (1219mm x 2438mm x 25mm) plate is to be handledalmost all the time with a lift magnet assembly. Occasionally, much heavier, larger, and thicker plates are to be encountered. Rather than sizing the mag- netic system for the heavier plates, consider sizing the magnet lift assembly to the common lightweight plates and plan to use other approaches on the rare heavier and larger plates.You could (a) use a sling and hook arrangement to lift the heavier plates bywelding temporary lift eyes on the heavier plates, or (b) perform any burning or cutting that would normally be...

(1) Percentage of sheet area actually contacting flush with the magnet face.(2) Quality of the path the sheet offers to the magnetic circuit from pole to pole. When a load is flat for a definable portion of its overall area, a simple calcula-tion of the proportion of the magnet face that is covered will allow us to esti- mate magnet holding power. For example, corrugated sheet is to be handled as illustrated. In this case half of the magnet face is covered, so the lifting power on this corrugated sheet is estimated to be about one half what it would be on a solid sheet of the same...

the permanent magnet are temporarilydiverted so that the holding power at the pole face is zero. Since there are no moving parts, there is no need for concern about a mechanical malfunction.Similar protection can be obtained frompermanent turn-off type magnets. These permanent lifting magnets use additional permanent elements that can be rotated into position to negate the lifting field. The turn- off cycle is manually activated, thereby making the holding and releasing function completely independent of an electrical power source.The magnetic holding power is never lostwith this type of...

SAFETY FACTOR Published lifting magnet capacities represent ultimate lift strength - the liftingcapacity of the magnet on different loads UNDER IDEAL CONDITIONS - unless clearly specified otherwise.It would be impossible to forsee all varying conditions of operation from oneinstallation to another and to try to rate the magnet for each and every possible condition of operation. Instead, the magnet specifier must do this by applying a Safety Factor to the ultimate lift strength of the magnet, making sure that the safety factor applied represents actual conditions as much as practical.Some of...