Q 1。 Since iron-based and cobalt-based magnetic strips are amorphous materials, they should have high permeability and can be used as anti-theft magnetic strips for books?
A: Theoretically. However, due to many factors, the magnetic properties of cobalt-based magnetic strips and iron-based magnetic strips are different. The main difference is that the permeability is not affected by stress. The magnetic permeability of iron-based magnetic stripe is greatly affected by stress, while the magnetic permeability of cobalt-based magnetic stripe is much less affected by stress. Users often find that the bought magnetic stripe gives an alarm through the channel of the book monitor, which is normal when there is no book, that is, the sensitivity is very high, but when the glue is put into the book and then passes through the anti-theft channel, it may not give an alarm, or the detection blind area is very large. This is the effect of stress. When the glue dries, the shrinkage of the paper makes the stress caused by the shrinkage of the iron-based magnetic stripe reduce the permeability, so the book monitor can't detect or can only detect weak signals, which reduces the sensitivity. After some iron-based magnetic strips are loaded with books, the sensitivity even drops to zero. The stress effect of cobalt-based magnetic stripe is much smaller than that of iron-based magnetic stripe.
Q2。 Is it always safe to use cobalt-based magnetic strips?
A: Not necessarily. Choosing a cobalt-based magnetic stripe is definitely much better than choosing an iron-based magnetic stripe. However, as mentioned earlier, the cobalt-based magnetic stripe also has the problem of stress influence, but it is much better than the iron-based magnetic stripe in degree, and there will be no case of zero sensitivity after loading books. (In general, the sensitivity of the positive stress cobalt-based magnetic strip will be about 40-70% of the original sensitivity after the book is loaded, while the sensitivity of the negative stress cobalt-based magnetic strip will not change after the book is loaded). For example, some libraries choose cobalt-based magnetic strips, but the sensitivity is still very low. What is the reason? The conditions for producing high-quality cobalt-based magnetic strips are that the cobalt content of the materials used should reach a certain proportion (60%-70%) and that the reasonable production technology should be ensured. At present, there are many companies producing magnetic stripe materials, but according to our scientific analysis, different manufacturers have different product components and formulas, and their cobalt content is also different; In addition, whether the production technology of materials is reasonable is closely related to the experience of operators. Therefore, it cannot be said that buying a cobalt-based magnetic stripe must be a high-quality magnetic stripe that meets the requirements.