Cheap magnetic drum

A cheap magnetic drum is not a compromise, but a technically sound choice. We saw how at crushing sites in the Kemerovo region and on recycling lines near Saratov, the same drum retained up to 98.7% of ferromagnetic inclusions at a load of 120 t/h - and at the same time remained within the budget even for enterprises with strict TCO. This is not a marketing formula. This is the result of 30 years of experience in the design of separators for the mining and processing industries.

Why "cheap" does not mean "unreliable"

The most common mistake is to consider the price of a magnetic drum directly related to its resource. In fact, three parameters are critical: induction on the surface of the working area, frame design and method of attaching the magnetic segment. For example, drums with induction below 120 mT begin to pass nails with a diameter of 3 mm already at belt speeds above 1.8 m/s. We have data on 47 unscheduled shutdowns at enterprises where they used budget models without a certified calculation of the magnetic field - in 82% of cases the reason was precisely metal slippage due to a weak field or uneven distribution.

LONGI Corporation uses a two-layer system for fastening magnetic segments: steel body + epoxy fill with a controlled coefficient of thermal expansion. This eliminates peeling during temperature changes from −35°C to +65°C. In real tests at the Fushun plant, such drums withstood 18,000 hours of continuous operation without a decrease in induction by more than 2.3%.

Where to really save money - and where not to

Savings are possible at three points - and only there:

• Drum shell material:steel 304 instead of 316 with a pH above 5.5 and the absence of chlorides;
• Cleaning system:manual scraper instead of automatic pneumatic release - if the interval between loadings exceeds 4 hours;
• Drive Configuration:a standard gear motor instead of an explosion-proof one - when operating outside the class B-IG zone.

You cannot skimp on the magnetic core. Cheap neodymium blocks with a neodymium content below 28% lose up to 15% of their strength in the first 6 months of operation. At LONGI, all drums are equipped with N48H magnets with a 10-year field stability guarantee. We don’t hide it: it’s 12–17% more expensive, but it reduces downtime by 63% and extends service life by 2.4 times.

How to choose a “cheap magnetic drum” without pitfalls

Before ordering, check four numbers - they decide everything:

1. Working induction— not less than 150 mT on the surface with the actual width of the tape;
2. Coverage angle— at least 180° for belt conveyors, 210° — if there is a risk of lateral flow of material;
3. Maximum material speed- indicated in the passport not as “up to 2 m/s”, but as “up to 2.1 m/s with a density of 1.8 t/m³ and fractions of 0–40 mm”;
4. Warranty life of bearings- at least 15,000 hours at the declared load.

If the documentation does not contain these values, request a magnetic field calculation diagram (usually in .pdf format marked “FEMM simulation”). More than 60% of “budget” offers on the Russian market do not pass this test.

Practice shows: price is only one line in the TCO calculation

At one plant in the Murmansk region, two options were compared: a drum for 1,250,000 rubles with a 2-year warranty and for 890,000 rubles with a 12-month warranty. After 14 months, the cheap option required replacement of the magnetic segment (210,000 ₽), repair of the support unit (145,000 ₽) and caused 3 emergency shutdowns of the workshop - the loss amounted to 4.2 million ₽. The final TCO was 29% higher.

A magnetic drum is cheap when it is designed for your task, and not for the price tag. When its parameters coincide with operating conditions, and not with general catalogs. When you receive not just a housing with magnets, but a documented field calculation, test report and installation recommendations - as the LONGI Corporation does. On the websiteljmagnet.ruTechnical calculators are available for selecting a drum according to your data: belt width, type of material, maximum humidity, loading frequency.

Reliability is not bought. It's being designed. And they check it - not in the office, but on the assembly line.