Holding magnets in round design for universal use


  • Holding force up to 2100N
  • Power 3 to 12.5W
  • Diameter 25 to 80mm
  • Armature plate as option
  • Description
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Electro-holding magnets - high force on flat surfaces

Electromagnets develop a high force on flat magnetic materials. We supply both pure steel (magnetic attraction upon energization) and permanent magnet (electrical release) versions of electric holding solenoids. Optional spring-loaded ejector pins are also available to overcome residual magnetism, as well as optional armature plates as magnetic counterparts for optimum holding performance. Most common electro-holding solenoids must be energized to develop force. Applications include door latches and restraints, holding ferromagnetic workpieces during machining or assembly, safety mechanisms, devices in textile machinery, and more. Since the magnetic field drops sharply with greater distance from the mating part, surface flatness and a very thin coating become important features. Therefore, to optimize the magnetic field, we recommend optional armature plates with very good surface.

What is an Electromagnet? General Technical Overview
The electromagnet is a simple holding device. When energized it will attach itself to a flat steel surface with high force. When de-energized the attracting force is switched off. Related devices include the following:
- Holding Magnets – employ a permanent magnet to attach to a flat ferromagnetic surface with high force
- HMER (Holding Magnet Electrical Release) – combines the function of holding and electromagnet to hold to a flat ferromagnetic surface with high force when no power is applied, and release from the surface when energized.

The most common construction for electromagnets is illustrated, the device comprises of a steel pot core with a coil fitted in an annular groove in the face of the electromagnet, the coil is commonly potted in place for environmental protection and improved thermal contact with the pot. The armature plate shown on top of the device is an optional accessory, as is the ejector pin fitted in the center of the part illustrated. The electromagnet is not intended to act over an extended distance, very high force is developed when in direct contact with a flat steel component, this force will reduce rapidly as separation between the electromagnet and steel surface increases. The surface of the mating component should be made as flat as possible and should be kept free from contamination which may cause separation of the two parts and consequent reduction in holding force. When de-energized, some residual magnetism may remain, in cases where this is problematic a spring-loaded ejector pin can be fitted to the device to separate this from the electromagnet when de-energized.

HMER – Holding Magnet Electrical Release 
HMER devices incorporate a permanent magnet so that high holding force is developed to a flat ferromagnetic component without external power being applied. Power is applied to the device with reverse polarity to counter the field due to the permanent magnet and release the ‘keeper’ component.

Electromagnets find application as holding devices in machinery, as latching devices in security systems, and as door holdback devices in large buildings such as hospitals where doors are held open to permit easy access but must be released to close if fire alarms are triggered, or in the case of power failure. HMER devices are used in applications such as cash drawers, drug dispensing trolleys, or key boxes / safes in secure environments where a limited level of security is needed to trace use of materials or prevent misappropriation. Due to the high forces and low power requirements, both constructions can find use as selection elements in applications where power is limited, or heat dissipation a problem such as shutter mechanisms, or selection mechanisms in textiles machinery. In handling and installation, and in many of the applications where they are employed, the device can be subject to harsh treatment which can deform the surface and impair holding force. Geeplus electromagnets can be supplied with a hardened surface finish which makes them highly resistant to such damage, this will become standard for most such devices for future production.

Installation Precautions
It is important that the Electromagnet and/or armature plate have some compliance in mounting allowing them to align parallel and ensure forces act normal to the interface between them.

Article No. Power Holding force at 20°C Dimensions Weight Feature/Option Images 3D Data sheet Order Wishlist
EM0025 3W 150N 25x20mm 60g Armature plate as option Order
EM0032 4W 280N 32x20mm 90g Armature plate as option Order
EM0040 5.5W 500N 40x27mm 200g Armature plate as option Order
EM0050 6W 750N 50x30mm 400g Armature plate as option Order
EM0080 12.5W 2100N 80x40mm 1450g Armature plate as option Order