The magnetic rubber sheet is a general term for elastomeric materials with magnetic properties. It is made from raw rubber, magnetic powder (magnetic filler) and other auxiliaries. Magnetic properties are the basic properties of magnetic rubber. Magnetic rubber exhibits different magnetic grades under the action of an external magnetic field, among which the strong magnetic grade is of high practical value.
Because magnetic rubber is not magnetic itself, its magnetism comes from a large number of magnetic powders (2 to 8 times the quality of raw rubber), so magnetic powder is indispensable for the manufacture of magnetic rubber. According to the composition, magnetic additives can be divided into metal magnetic powder and iron-cobalt fraction, iron-nickel powder and iron barium powder, among which iron cobalt powder is the most widely used. The metal magnetic powder is seldom used because of its high price and being difficult to add. At present, ferric oxide is used more. They are an iron oxide and some of the two valence metal compounds. Even the same kind of ferrite magnetic powder causes different final magnetic strength because of the different crystalline form, size, and uniformity. The manufacturing process of rubber magnetic sheets
is much the same as that of other products. In the formulation design, we must first determine the variety, size, and dosage of the magnetic powder. Next, choose rubber according to the requirements, such as choosing natural rubber for wear-resistant. During processing, before and after vulcanization, it is necessary to add magnetization procedures without other products to give permanent magnetism to products. The advantage of magnetization before vulcanization is that the direction of the external magnetic field is constant, it will be smoother to go through the rubber network. After vulcanization, the permeability of the magnetization is poor, but the operation is more convenient. In a word, each has its own advantages and disadvantages.
The physical quantities used to characterize magnetic properties include magnetic intensity, residual magnetic susceptibility, magnetic energy product and so on. Among them, the magnetic intensity is the most commonly used, and the unit of measurement is Gauss(GS). The magnetic rubber is generally required to reach the range of 100 - 600GS.