A permanent magnetic lifter, also called a permanent lifting magnet, is a below-the-hook device used to lift suitable ferromagnetic loads without an external electrical supply. Its holding ability depends on much more than load weight. Material, thickness, contact area, surface condition, shape, temperature, balance, and the direction of force all affect whether a particular magnet is suitable.
Relevant Liftool product context: permanent magnetic lifters.
Quick Answer
A permanent magnetic lifter uses a switchable magnetic circuit to grip suitable steel loads. Many manual models use a lever to redirect magnetic flux through the load for lifting and back inside the magnet for release. No external power is needed, but the device is not a universal attachment for every metal or every steel shape. Select it from the manufacturer's load chart for the actual material, thickness, flat or round surface, air gap, temperature, orientation, and center of gravity. Before lifting, confirm identification and rated capacity, inspect the magnet and suspension parts, clean the contact area, engage and lock the handle correctly, make a controlled low test lift when permitted, and keep people out of the load path.
What Is a Permanent Magnetic Lifter?
A permanent magnetic lifter is a lifting attachment that creates a magnetic holding force between its pole face and a ferromagnetic load. It is normally suspended from a crane, hoist, or other suitable lifting machine through its lifting eye or attachment point.
In many manually operated designs, permanent magnet elements are arranged inside the body. Moving the operating handle changes the magnetic circuit:
- In the ON position, magnetic flux is directed through the pole face and the load.
- In the OFF position, the flux is largely redirected within the lifter so the load can be released.
- A mechanical lock or latch helps prevent unintended handle movement while the magnet is engaged.
Designs differ, so this description is a general operating principle rather than a substitute for the instructions supplied with a specific unit. A magnet must never be assumed to be safe merely because its handle reached the ON position.
What Materials Can It Lift?
Permanent lifting magnets are intended for materials that provide a suitable magnetic path. Carbon and mild steels are common applications, but alloy, heat treatment, composition, geometry, and surface condition can change magnetic response.
They are not suitable for non-ferromagnetic materials such as aluminium, copper, brass, wood, or plastic. Stainless steel cannot be judged by name alone: some grades are weakly magnetic or effectively non-magnetic in the intended lifting condition. When material identity or response is uncertain, obtain competent technical confirmation rather than relying on a small hand magnet or visual appearance.
Typical applications include:
- steel plate and blocks;
- dies, machine parts, and suitable cast or forged components;
- flat stock at cutting and machining stations;
- round bar or pipe when the magnet has an approved pole shape and a separate round-load rating.
The device should not be treated as general-purpose lifting gear. Suitability must be established for the actual load family and working environment.
Why Rated Capacity Is Conditional
The number on a magnet's nameplate is meaningful only with the conditions defined by its manufacturer. A load can be below the nominal rating and still be unsuitable if the magnetic circuit is poor or the load can peel, tilt, or slide.
| Load factor | Why it matters | What to confirm |
|---|---|---|
| Material | Different metals and steel conditions provide different magnetic response. | Material grade or verified magnetic suitability. |
| Thickness | Thin material may not carry the full magnetic flux assumed by the rating. | Minimum thickness and any capacity reduction in the load chart. |
| Contact area | Partial contact reduces the usable magnetic path. | The pole face sits fully on a suitable area of the load. |
| Air gap | Rust scale, paint, dirt, oil, coatings, weld spatter, and roughness can separate the pole face from the load. | Permitted surface condition and the applicable derating. |
| Shape | Round loads touch a smaller part of the pole face than flat loads. | A specific round-load rating and approved diameter range. |
| Length and stiffness | Long or flexible material can sag and peel away from a single magnet. | Overhang, deflection, and whether multiple magnets or a lifting beam are required. |
| Center of gravity | An off-center magnet can allow a load to tilt or slide. | Magnet position and load balance before travel. |
| Temperature | Heat can reduce magnetic performance or damage components. | Load and ambient temperature limits for the exact model. |
| Lift direction and motion | Side pull, tilt, shock, rapid acceleration, or swinging can impose forces not represented by a vertical static rating. | Approved orientation, operating speed, and movement limits. |
Do not invent a universal safety factor or temperature range. Use the rating plate, instructions, load chart, test documentation, and local lifting plan for the specific magnet.
Flat Loads, Round Loads, and Thin Sheet
Flat loads
Flat, clean steel plate usually offers the most complete contact, but the plate must still meet thickness, material, stiffness, and surface requirements. A large plate may need more than one magnet even when its weight appears to fit one unit, because unsupported ends can droop and create a peeling action.
Round loads
Round bar and pipe provide line contact rather than full flat contact. Use only a magnet designed and rated for round loads, and check the permitted diameter and capacity. A flat-load rating must not be copied across to round stock.
Thin sheet and stacked material
A magnet may attract more than the intended top sheet, while the lower sheet has less direct contact and may separate during travel. Unless the equipment and procedure are specifically designed for the task, lift one identified item at a time and control the area for falling material.
Permanent, Electric, and Electro-Permanent Magnets
These terms describe different ways of producing or controlling the magnetic field.
| Type | Power during holding | Main selection issue |
|---|---|---|
| Permanent lifting magnet | Normally no external power; often switched manually. | Correct engagement, contact conditions, load chart, and mechanical control integrity. |
| Electric lifting magnet | Electrical power produces the holding field. | Power continuity, controls, warning systems, and backup or secondary measures where required. |
| Electro-permanent magnet | Electrical energy changes the magnetic state; continuous power may not be required to hold. | Control design, status indication, release protection, and application-specific instructions. |
The absence of a power cable does not remove the risk of a dropped load. Permanent magnets remain dependent on correct selection, inspection, contact, and operation.
Selection Checklist
Before requesting a quotation, define the load and the operation rather than sending only a maximum weight.
- Load material: grade or a technically reliable description of the steel.
- Weight range: minimum, typical, and maximum load, including any attached parts.
- Dimensions: length, width, thickness, and any curved or irregular surfaces.
- Surface: mill scale, rust, paint, oil, coatings, machining marks, or unevenness.
- Shape: flat plate, block, round bar, pipe, casting, or fabricated assembly.
- Stiffness and balance: expected deflection, overhang, and center-of-gravity position.
- Handling path: vertical lift, travel distance, lift height, acceleration, and any requested tilting.
- Environment: load and ambient temperatures, moisture, contamination, and restricted areas.
- Lifting machine: hook size, headroom, crane or hoist capacity, and attachment arrangement.
- Compliance needs: marking, instructions, test records, examination documents, and site requirements.
If one magnet cannot maintain stable contact and load balance, the solution may require multiple synchronized magnets, a purpose-designed lifting beam, or a different lifting method.
Checks Before Use
The detailed inspection and test process must follow the manufacturer, the employer's lifting-equipment program, and local law. A practical pre-use review normally includes:
- verify the magnet's identity, rating plate, and applicable load chart are legible;
- confirm the inspection or examination status is current for the place of use;
- inspect the lifting eye, body, pole face, handle, latch, fasteners, and any associated chain or connector;
- remove loose contamination from the magnet face and the intended load contact area;
- confirm the load material, weight, thickness, shape, surface, and center of gravity;
- position the magnet so the load can remain balanced without side pull;
- move the handle through the specified sequence and confirm the lock is fully engaged;
- if permitted by the instructions and lifting plan, raise the load only slightly and pause to confirm stable attachment and balance;
- keep the load as low as practicable during travel, avoid shock and uncontrolled motion, and prevent anyone entering the fall zone;
- land the load on a stable support before operating the release control.
Remove the magnet from service if identification is missing, the pole face or suspension parts are damaged, the handle or lock does not operate correctly, the load cannot be verified, or stable attachment is uncertain. Do not improvise repairs or continue by applying an undocumented capacity reduction.
Inspection and Legal Context
The UK Health and Safety Executive's magnetic lifting-device guidance notes that these devices may be lifting equipment or lifting accessories under Great Britain's LOLER framework, depending on how they are installed. Its guidance also emphasizes load material, thickness, shape, contact, flexibility, balance, exclusion zones, training, inspection, and manufacturer information. These principles are useful for risk review, but legal duties and examination intervals must be determined for the country and workplace where the equipment is used.
No article can set one universal inspection interval. The schedule depends on the equipment, service, environment, manufacturer instructions, risk assessment, and applicable regulations. Thorough examination or testing must be carried out by a competent person where required.
FAQ
Does a permanent magnetic lifter need electricity?
Most manual permanent lifting magnets do not need external electrical power to hold the load. Their magnetic circuit is switched mechanically. This avoids power-loss release associated with ordinary electric magnets, but it does not make the lift independent of material, contact, capacity, inspection, or operating conditions.
Can it lift stainless steel?
Not as a general rule. Stainless steels vary greatly in magnetic response. Some grades are effectively non-magnetic for lifting, and others may not provide the performance assumed by the load chart. Confirm the exact material and obtain technical approval for the intended device.
Can the flat-load rating be used for round bar or pipe?
No. Round loads have different contact geometry and normally require a magnet designed for that shape, with a separate capacity and diameter range. Use the manufacturer's round-load chart.
Is a test lift enough to prove the magnet is suitable?
No. A controlled low lift can help reveal imbalance or poor attachment, but it does not replace material identification, capacity calculation, surface assessment, inspection, instructions, or a properly planned lifting operation.