Neodymium – iron – boron high-gradient magnetic rod
Schematic diagram for NdFeB magnetic rod
- End sections bolted to magnetic rod – better mechanical stability
- Magnets and iron disks are accurately aligned and bolted together outside of the pipe – low wear of rust-free pipe during stripping
- Use of high-quality, highly coercive NdFeB magnet material
- Maximum flux density 13.0 kG on rod surface (flux density on effective surface)
Neodymium-iron-boron high-gradient magnetic rod
Magnetic rods are used for filtering fine magnetic particles from fluids or powders.
By using suitable and high-quality neodymium-iron-boron magnets, particularly high field strengths are achieved on the rod surface. A high field strength on the surface combined with a high field strength gradient results in particularly high force effects on magnetizable particles.
This means, the higher the flux density, the more efficient the separation. Significantly smaller and significantly more particles are removed.
Where “cheap” NdFeB magnet material (high remanance but low coercive force) is used, the magnet material is subjected to magnetic reversal in the area of the iron pole disks. Slight increases in temperature reduce the coercive force of NdFeB, causing further magnetic reversal, i.e. the flux density at the rod surface reduces further when using slightly higher operating temperatures.
We only use high-quality, high-coercive NdFeB magnet material with a high remanence and high coercive force, ensuring that no magnetic reversal occurs in the area around the pole disks. The ratio of magnet length to pole disk thickness is matched to the magnet material and the application, using finite element calculations. Evaluation options are available that directly demonstrate the effective range of iron particles, the specific force density.
Finite Element Analysis (FEA)
A Finite Element Analysis is carried out to determine the size of the magnet and the effective range for the respective requirements.
Practical application of permanent magnet
Increasing requirements as regards the purity of food, products, raw material, operating material as well as the requirement for a longer service life of plants, have resulted in more and more producers improving their manufacturing processes. In particular the proportion of ultra-fine contaminating iron particles (abrasion, contained in raw material, etc.) and their effects are still underestimated by many sectors.
A cost-effective way of combating this problem is the use of high-performance permanent magnets. Already during the selection of the equipment, the requirements and the client´s operating conditions are taken into consideration.
As a result of the used high-performance magnets and of the design, particularly high surface flux densities of up to 1.3 Tesla (13,000 Gauss) and retention forces are achieved so that contaminating iron particles from 5 µm are removed in liquid products and from 25 µm in powdery products. The surface flux density should not be confused with the remanence of the used magnet material, the so-called, Br value but represents the actual measurable value on the magnet rod surface.
The specific material selection ensures the long service life of the components. Surface flux densities will not decrease (de-magnetize) under specified operating conditions.
In contrast to standard metal detection equipment, high-performance magnets only remove contaminating iron particles from the product flow, making the usual particle removal process superfluous. Practical experience shows that approx. 80%-90% of contaminating particles can be magnetized and can thus be removed from the product flow using magnet filters.
In explosion-proof parts of plants, high performance magnets can be used to comply with ATEX regulations by keeping spark-producing particles to a minimum.