Leading permanent lifting magnet

The driving permanent lifting magnet is not just a tool for moving metal. This is the intersection of physics, safety and production logistics. We saw how in a warehouse in Yekaterinburg the operator restarted the crane three times due to the load slipping on the electromagnet. After replacing withleading permanent lifting magnet- not a single failure in 14 months. The difference is not in power, but in predictability.

Why “constant” is not about the absence of current, but about fault tolerance

Many people confuse “permanent” with “non-nutrient”. In fact, it is a magnet based on rare earth neodymium alloys NdFeB, where the magnetic field is created by the structure of the crystal lattice, and not by an external source. Current is needed only once - to turn on/off the locking mechanism. The rest of the time the load is held without energy, without heating, without the risk of blackout.

We tested three types: electromagnets with battery backup, hydraulic grippers and permanent magnets - at -25°C, 92% humidity and frequent cycles (more than 120 lifts per hour). Only the permanent magnets retained 100% holding force at the 8th hour of operation. Electromagnets lost 17%, hydraulics - 23% due to oil viscosity.

The key parameter is not the nominal force in kN, butseparation safety factor. For reliable models, it is not lower than 2.2: if 8 tf is stated, a load weighing up to 17.6 t can actually be held with perfect contact. But - and this is important - only on a clean, flat, uncoated surface. Rust, paint, slag reduce efficiency by 30–60%. We always check a sample of the cargo directly at the client's site.

Where “leading” is not marketing, but engineering reality

The word “leader” in the title is not an abstraction. This means: the industry's first certified design with triple armature position control, built-in temperature sensor and automatic slack compensation. Such a magnet does not just “hold”. It reports: “Load captured”, “Gap exceeded”, “Temperature critical” - through the RS-485 digital interface or discrete outputs.

At the Tyumen plant we encountered a problem: operators did not notice weak pressure when working with 6mm thick sheets. Old magnets gave a “capture” signal even with an air gap of 0.8 mm. Newleading permanent lifting magnetwith an optical distance sensor, the lift was turned off until the gap became ≤0.15mm. Zero incidents.

Operating temperature: −40°C to +80°C (no power loss)
Active element service life: at least 25 years with cycles up to 10,000 starts
On/off switching time: 0.8–1.2 seconds (depending on weight)
Corrosion protection: multi-layer nickel-chrome plating + epoxy sealant coating

What breaks magnets - and how to avoid it

The most common cause of failure is not overload, but shock. Not when a load falls, but when it is suddenly dropped onto a steel plate. Even a single impact with acceleration >15g causes microcracks in the neodymium core. We recommend installing 85 Shore A polyurethane damper pads - they reduce shock loads by 70%.

The second mistake is ignoring maintenance. Once a quarter you need to check: the integrity of the housing, the tightening of fastening bolts of strength class 10.9, the cleanliness of contact surfaces. Dirt and metal dust are the main enemies. We provide customers with a set of abrasive coated cleaning brushes and a table of acceptable wear - in millimeters, not in "percentage of wear".

And one more thing: not all steels are equally magnetic. Austenitic stainless steels (for example, 08Х18Н10) are practically non-magnetic. If your cargo consists of parts made of such alloys, a permanent magnet will not work. A combined grip is needed here. We always ask clients to send a sample of the material - and we do a test lift in the LONGI laboratory.

How to choose - and why the decision is made not in the office, but on the site

The choice begins with three questions that we ask each customer:

What is the minimum thickness and maximum surface roughness of the load?
How often do loads change - and is quick changeover required without tools?
Are there aggressive environments in the work area: salt fog, chemical fumes, abrasive dust?

It is not the model that depends on the answers, but the entire architecture of the solution: the type of fastening (ring, hook, flange), the presence of remote control, the design of the housing (IP67 or IP69K), the material of the protective coating. For example, for a metallurgical workshop in Magnitogorsk we used a magnet with a titanium body and ceramic guides - the service life increased from 3 to 11 years.

LONGI Corporation has been developing such solutions since 1993. Today, its production base in Fushun produces more than 4,000 pieces of mining equipment per year. More than 60% of engineers have a higher technical education - and each of them has spent at least 200 hours at industrial sites. That's why theyleading permanent lifting magnetnot just complies with GOST R ISO 12100, but takes into account how crane vibration affects the distribution of magnetic flux, how humidity changes the coefficient of friction between steel and coating, and why “mean time between failures” is a meaningless indicator without specifying test conditions.

Reliability is not measured in kilonewtons. It is measured in days without downtime, in the absence of emergency stops, in the fact that the operator does not look at the instruments - he looks at the load. That's exactly how it worksleading permanent lifting magnet.