CM PML-6 / N45 - magnetic gripper

Advantages and disadvantages of rare earth magnets.

Besides their immense pulling force, neodymium magnets offer the following advantages:

• Their magnetic field remains stable, and after around ten years it drops only by ~1% (theoretically),
• They are extremely resistant to demagnetization induced by external disturbances,
• In other words, due to the metallic layer of nickel, the element becomes visually attractive,
• Magnetic induction on the top side of the magnet is maximum,
• Neodymium magnets are characterized by very high magnetic induction on the magnet surface and can work (depending on the form) even at a temperature of 230°C or more...
• Possibility of accurate modeling as well as adapting to precise applications,
• Significant place in modern industrial fields – they serve a role in magnetic memories, brushless drives, medical equipment, also multitasking production systems.
• Compactness – despite small sizes they provide effective action, making them ideal for precision applications

What to avoid - cons of neodymium magnets and proposals for their use:

• Susceptibility to cracking is one of their disadvantages. Upon strong impact they can fracture. We advise keeping them in a special holder, which not only secures them against impacts but also increases their durability
• We warn that neodymium magnets can reduce their strength at high temperatures. To prevent this, we advise our specialized [AH] magnets, which work effectively even at 230°C.
• Magnets exposed to a humid environment can rust. Therefore when using outdoors, we recommend using waterproof magnets made of rubber, plastic or other material protecting against moisture
• Due to limitations in realizing nuts and complex shapes in magnets, we recommend using a housing - magnetic mechanism.
• Potential hazard related to microscopic parts of magnets are risky, in case of ingestion, which becomes key in the context of child safety. Additionally, small components of these devices can be problematic in diagnostics medical in case of swallowing.
• Higher cost of purchase is one of the disadvantages compared to ceramic magnets, especially in budget applications

Maximum lifting capacity of the magnet – what it depends on?

Breakaway force is the result of a measurement for the most favorable conditions, assuming:

• with the contact of a yoke made of low-carbon steel, guaranteeing maximum field concentration
• possessing a massiveness of minimum 10 mm to ensure full flux closure
• characterized by lack of roughness
• without any clearance between the magnet and steel
• for force acting at a right angle (in the magnet axis)
• at ambient temperature room level

Lifting capacity in practice – influencing factors

In practice, the actual lifting capacity is determined by several key aspects, listed from most significant:

• Air gap (betwixt the magnet and the metal), as even a tiny clearance (e.g. 0.5 mm) results in a reduction in lifting capacity by up to 50% (this also applies to paint, rust or dirt).
• Force direction – note that the magnet holds strongest perpendicularly. Under sliding down, the holding force drops significantly, often to levels of 20-30% of the maximum value.
• Steel thickness – too thin steel does not close the flux, causing part of the flux to be lost to the other side.
• Plate material – mild steel gives the best results. Higher carbon content reduce magnetic properties and lifting capacity.
• Base smoothness – the smoother and more polished the plate, the better the adhesion and higher the lifting capacity. Unevenness creates an air distance.
• Temperature – temperature increase causes a temporary drop of induction. Check the maximum operating temperature for a given model.

* Lifting capacity was determined using a steel plate with a smooth surface of optimal thickness (min. 20 mm), under perpendicular pulling force, whereas under parallel forces the load capacity is reduced by as much as 5 times. In addition, even a slight gap {between} the magnet’s surface and the plate decreases the holding force.