We are asked many times about the shelf life of permanent magnets. The simple answer is, no, there is no shelf life; however, as all things go with magnets, it is not that simple…
Breakaway force, holding force, fixturing force – “How can all of these represent the same measurement?” a younger engineer recently inquired. Engineers and non-engineers alike can be puzzled trying to understand some of the commonly used – but potentially misinterpreted – terms related to the concept of a magnet’s pull force.
These phrases are often used to represent “strength” when writing magnetic specifications. They also may be mentioned when anticipating the work required of a magnet within an application. To add to the potential confusion, maximum holding force or how much tensile force is exerted by any magnet, is often shown in online calculators – like our neodymium pull force calculator – are based on theoretical calculations of flux density.
The maximum operating temperature of a magnet is an important property, but it is simply the point beyond which the magnet will experience an irreversible loss in net magnetization. In actuality, a magnet will lose net magnetization as soon as it starts to heat up. This loss is called “reversible” as it is recovered as soon as the magnet cools back down. While avoiding irreversible loss may seem to be the primary concern, even reversible loss can cause a negative impact on a magnet’s performance because while the magnet does not permanently demagnetize, it may not generate enough field for a given application at a particular operating temperature.
It is not uncommon to see distributors of magnets advertise their products at holding values far above what those magnets will reasonably achieve in a real world setting. Why would empirical results be lower than listed holding force values? It may be that the listed force was based on testing completed under the most ideal […]
There are limits to how much induced magnetism is possible in different materials and similar workpieces of varying size, shape and configuration. The principle of magnetic saturation observes that there is a point of diminishing returns at which attempting more externally applied magnetic field (H) will give rise to no additional magnetic induction (B). Increasing the thickness of a workpiece is generally beneficial. However, these changes will likely impact cost, mass, and possibly ease of manufacturing. It is therefore beneficial to understand and control for the magnetic saturation of materials during the design stage…
How do you QC a permanent magnet, magnetic assembly, or a piece of equipment utilizing magnets? There are several methods which will pass a Gage R & R, but they are generally unknown to people outside of the magnet industry. Much of the technical data about magnetic fields, both commonly published and taught at the […]
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