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neodymium magnets

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SM 25x325 [2xM8] / N42 - magnetic roller

magnetic separator

catalog number 130349

no reviews

diameter Ø

25 mm


325 mm

max. temperature

≤ 80 °C

910.20 PLN gross price (including VAT) / pcs +

740.00 PLN net price + 23% VAT / pcs

bulk discounts:

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Specification: magnetic separator 25x325 [2xM8] / N42

Characteristics: magnetic separator 25x325 [2xM8] / N42
production / distribution
Dhit sp. z o.o.
country of origin
Poland / China / Germany
customs code
diameter Ø ?
25 mm
height ?
325 mm
max. temperature ?
≤ 80 °C
0.01 g
execution tolerance
± 0.1 mm
rodzaj materiału
AISI 304 - bezpieczna dla żywności
rodzaj magnesów
NdFeB N42
ilość gwintów
2x [M8] wewnętrzne
obwodowa - 12 nabiegunników
indukcja magnetyczna
~ 6 500 Gauss [±5%]
max. temp. pracy
poniżej ≤ 80°C
grubość rury osłonowej
1 mm

Magnetic properties of the material N42

material characteristics N42
remenance Br [Min. - Max.] ?
remenance Br [Min. - Max.] ?
coercivity bHc ?
coercivity bHc ?
actual internal force iHc
≥ 12
actual internal force iHc
≥ 955
energy density [Min. - Max.]
BH max MGOe
energy density [Min. - Max.]
BH max KJ/m
max. temperature
≤ 80

Physical properties of sintered neodymium magnets Nd2Fe14B

Physical properties of sintered neodymium magnets Nd2Fe14B
Vickers hardness
Curie Temperature TC
312 - 380
Curie Temperature TF
593 - 716
Specific resistance
Bending strength
Compressive strength
Thermal expansion parallel (∥) to orientation (M)
(3-4) x 106
Thermal expansion perpendicular (⊥) to orientation (M)
-(1-3) x 10-6
Young's modulus
1.7 x 104
The main mechanism of the magnetic separator is the use of neodymium magnets, which are placed in a casing made of stainless steel usually AISI304. In this way, it is possible to precisely remove ferromagnetic particles from different substances. A key aspect of its operation is the repulsion of N and S poles of neodymium magnets, which enables magnetic substances to be collected. The thickness of the magnet and its structure's pitch determine the power and range of the separator's operation.
Generally speaking, magnetic separators serve to extract ferromagnetic elements. If the cans are ferromagnetic, the separator will effectively segregate them. However, if the cans are made of non-ferromagnetic materials, such as aluminum, the separator will not effectively segregate them.
Yes, magnetic rollers are used in the food industry to clear metallic contaminants, such as iron fragments or iron dust. Our rods are made from durable acid-resistant steel, AISI 304, suitable for use in food.
Magnetic rollers, otherwise cylindrical magnets, are employed in metal separation, food production as well as recycling. They help in extracting iron dust in the course of the process of separating metals from other materials.
Our magnetic rollers consist of neodymium magnets embedded in a stainless steel tube cylinder of stainless steel with a wall thickness of 1mm.
From both sides of the magnetic bar can be with M8 threaded openings, enabling simple mounting in machines or magnetic filter drawers. A "blind" version is also possible in manual separators.
In terms of features, magnetic bars stand out in terms of flux density, magnetic force lines and the area of operation of the magnetic field. We produce them in two materials, N42 as well as N52.
Usually it is believed that the greater the magnet's power, the more effective. Nevertheless, the strength of the magnet's power is dependent on the height of the used magnet and the quality of the material [N42] or [N52], as well as on the area of use and expected needs. The standard operating temperature of a magnetic bar is 80°C.
If the magnet is more flat, the magnetic force lines are short. Otherwise, in the case of a thicker magnet, the force lines will be longer and reach further.
For creating the casings of magnetic separators - rollers, usually stainless steel is used, especially types AISI 304, AISI 316, and AISI 316L.
In a salt water contact, AISI 316 steel exhibits the best resistance thanks to its exceptional anti-corrosion properties.
Magnetic rollers are characterized by their unique configuration of poles and their capability to attract magnetic particles directly onto their surface, as opposed to other separators that often use complex filtration systems.
Technical designations and terms related to magnetic separators include among others polarity, magnetic induction, magnet pitch, as well as the type of steel used.
Magnetic induction for a magnet on a roller is measured using a teslameter or a gaussmeter with a flat Hall-effect probe, seeking the highest magnetic field value near the magnetic pole. The result is verified in a value table - the lowest is N30. All designations below N27 or N25 suggest recycling that falls below the standard - they are not suitable.
Neodymium magnetic rollers offer many advantages, including a very strong magnetic field, the ability to capture even the tiniest metal particles, and durability. On the other hand, among the drawbacks, one can mention higher cost compared to other types of magnets and the need for regular maintenance.
To properly maintain of neodymium magnetic rollers, it is recommended {to clean them regularly from deposits, avoid extreme temperatures up to 80°C, and cleaning regularly, avoiding temperatures above 80 degrees. The rollers have an IP67 waterproof rating, so if they are not watertight, the magnets inside may rust and lose their strength. Roller inspections are advised to be conducted every two years. Care should be taken as there is a possibility of finger injury. If the protective tube is only 0.5 mm thick, it can be worn down, which, in turn, may lead to issues with the magnetic rod becoming unsealed and product contamination. The Roller operating range equals its diameter, fi25mm is approximately 25mm active range, while fi32 is about 40mm.

Compilation of suggested goods

Advantages as well as disadvantages of neodymium magnets NdFeB.

In addition to immense strength, neodymium magnets have the following advantages:

  • They do not lose power over time - after 10 years, their strength decreases by only ~1% (theoretically),
  • They are highly resistant to demagnetization by external magnetic sources,
  • In other words, thanks to the glossy nickel, gold, or silver finish, the element gains an visually attractive appearance,
  • They have exceptionally high magnetic induction on the surface of the magnet,
  • Thanks to their high temperature resistance, they can operate (depending on the shape) even at temperatures up to 230°C and above...
  • Due to the option of accurate forming or adaptation to individual needs – neodymium magnets can be produced in a wide range of shapes and sizes, which expands the range of their possible uses.
  • Significant importance in advanced technologically fields – find application in hard drives, electric motors, medical devices and various technologically advanced devices.

Disadvantages of neodymium magnets:

  • They can break when subjected to a powerful impact. If the magnets are exposed to impacts, we recommend using magnets in a steel housing. The steel housing in the form of a holder protects the magnet from impacts, and at the same time increases its overall strength,
  • Magnets lose their strength due to exposure to high temperatures. In most cases, when the temperature exceeds 80°C, these magnets experience permanent loss in strength (although it is worth noting that this is dependent on the shape and size of the magnet). To avoid this problem, we offer special magnets marked with the [AH] symbol, which exhibit high temperature resistance. They can operate even at temperatures as high as 230°C or more,
  • They rust in a humid environment. For outdoor use, we recommend using waterproof magnets, such as those made of rubber or plastic,
  • The use of a cover or a magnetic holder is recommended due to the limited possibilities of manufacturing threads or complex shapes in the magnet
  • Potential hazard associated with microscopic parts of magnets are risky, in case of ingestion, which becomes significant in the aspect of protecting young children. It's also worth noting that tiny parts of these devices can hinder the diagnostic process when they are in the body.

Safety Precautions

Do not bring neodymium magnets close to GPS and smartphones.

Magnetic fields interfere with compasses and magnetometers used in navigation for air and sea transport, as well as internal compasses of smartphones and GPS devices.

Avoid contact with neodymium magnets if you have a nickel allergy.

Studies clearly indicate a small percentage of people who suffer from metal allergies such as nickel. An allergic reaction often manifests as skin redness and rash. If you have a nickel allergy, try wearing gloves or avoid direct contact with nickel-plated neodymium magnets.

Dust and powder from neodymium magnets are highly flammable.

Do not attempt to drill into neodymium magnets. Mechanical processing is also not recommended. Once crushed into fine powder or dust, this material becomes highly flammable.

Magnets made of neodymium are highly susceptible to damage, resulting in their cracking.

Neodymium magnets are extremely fragile, and by joining them in an uncontrolled manner, they will crack. Neodymium magnets are made of metal and coated with a shiny nickel, but they are not as durable as steel. In the event of a collision between two magnets, there may be a scattering of fragments in different directions. Protecting your eyes is crucial in such a situation.

It is crucial not to allow the magnets to pinch together uncontrollably or place your fingers in their path as they attract to each other.

If have a finger between or on the path of attracting magnets, there may be a severe cut or even a fracture.

  Neodymium magnets should not be around youngest children.

Neodymium magnets are not toys. Do not allow children to play with them. In the case of swallowing multiple magnets simultaneously, they can attract to each other through the intestinal walls. In the worst case scenario, this can lead to death.

People with pacemakers are advised to avoid neodymium magnets.

Neodymium magnets produce strong magnetic fields that can interfere with the operation of a heart pacemaker. Even if the magnetic field does not affect the device, it can damage its components or deactivate the entire device.

You should keep neodymium magnets at a safe distance from the wallet, computer, and TV.

Strong fields generated by neodymium magnets can damage magnetic storage media such as floppy disks, credit cards, magnetic ID cards, cassette tapes, video tapes, or other similar devices. In addition, they can damage televisions, VCRs, computer monitors, and CRT displays. You should especially avoid placing neodymium magnets near electronic devices.

Comparing neodymium magnets to ferrite magnets (found in speakers), they are 10 times stronger, and their strength can surprise you.

Read the information on our website on how to properly utilize neodymium magnets and avoid significant harm to your body and unintentional disruption to the magnets.

Neodymium magnets can become demagnetized at high temperatures.

Although magnets are generally resilient, their ability to retain their magnetic strength can be influenced by factors like the type of material used, the magnet's shape, and the intended purpose for which it is employed.

In order for you to know how powerful neodymium magnets are and why they are so dangerous, read the article - Dangerous strong neodymium magnets.

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tel: +48 888 99 98 98