The Concept of Isostatic Pressing and Its Advantages and Disadvantages
Isostatic press is a type of isostatic press that pressurizes objects under high pressure. It is gradually pressurized by a pressurizing system, and pressure is transmitted through liquid, so that the surface of the object is subjected to a uniform pressure, and under the constraint of the mold, the molding is formed. process. In the process of compaction, the distance between the actual workpiece molecules is reduced, and the density is increased, which makes the physical properties and even chemical properties of the restricted items change. The isostatic press uses oil, water or gas as the working medium, and applies the same high pressure to all surfaces of the object. It can make the formed workpiece have the characteristics of high and uniform density, uniform sintering shrinkage and easy machining. It is widely used in magnetic materials, ceramics, cemented carbide, high temperature refractory materials, rare earth permanent magnets, carbon materials, rare metal powders and other industries. The isostatic press uses oil, water or gas as the working medium, and applies the same high pressure to all surfaces of the object. It can make the formed workpiece have the characteristics of high and uniform density, uniform sintering shrinkage and easy machining. It is widely used in magnetic materials, ceramics, cemented carbide, high temperature refractory materials, rare earth permanent magnets, carbon materials, rare metal powders and other industries.
(1) The compact density is high. The density of samples prepared by isostatic pressing is generally five to fifteen percent higher than that of one-way and two-way compression molding, and the relative density of samples prepared by hot isostatic pressing can reach 90%. 9.8 to 99.09 percent.
(2) The density of the green compact is uniform. In the molding process, whether it is one-way or two-way pressing, due to the existence of frictional resistance between the powder and the steel mold and the decrease of the molding pressure during the transmission process, the phenomenon of uneven density distribution of the green compact will occur. The difference can often reach more than ten percent when pressing complex-shaped products. In isostatic pressing, the sample is subjected to equal force in all directions, the force and shrinkage of the sheath and the powder are roughly the same, the relative movement of the powder and the sheath is very small, the pressure only decreases slightly, and the density difference of each part of the sample is less than One percent, the density distribution can be considered uniform.
(3) Samples with large aspect ratio and complex shape can be prepared. Because the green body is subjected to the same force everywhere and the density distribution is uniform, samples with large aspect ratio and complex shape can be produced.
(4) The isostatic pressing process generally does not need to add lubricant to the powder, which not only reduces the pollution to the product, but also simplifies the manufacturing process.
(5) The products formed by isostatic pressing have excellent performance and lower sintering temperature than samples obtained by other molding methods.
(6) The disadvantage of the isostatic pressing process is that the process efficiency is low and the equipment is expensive.
