Dry-bag Isostatic Pressing Molds and Wet-bag Isostatic Pressing Molds for Powder Metallurgy
Dry-bag Isostatic Pressing Molds and Wet-bag Isostatic Pressing Molds for Powder Metallurgy
Isostatic pressing is to pack the powder in a flexible mold, then immerse it in the fluid and apply pressure, and the pressure acts uniformly on the powder body through the outer surface of the flexible mold. Uniform force can effectively eliminate the friction between the powder and the female mold, which is superior to conventional pressing, and the uneven force of conventional force is the main reason affecting the quality of the blank. Isostatic pressing is when the pressure acts on the fluid, the pressure is transmitted to the metal powder through the mold, so as to complete the pressing of the powder metallurgy product.
1. Wet bag cold isostatic pressing
The powder is sealed in a flexible bag and placed in a pressurized liquid. Flexible pack is made of polyurethane, silicone rubber, neoprene or natural rubber. The sheath is made by dipping or spraying, mechanical pressing, pouring molding or injection molding. After the package is filled with powder and sealed, it is all submerged in the pressure medium. The pressure medium is usually water with added lubricants and preservatives.
In addition to uniform production density, this method has other advantages over conventional pressing. For example, wet bag cold isostatic pressing can produce special-shaped powder metallurgy products with large height-to-diameter ratio, concave corners and grooves, and thin-walled cross-sections, etc. Static pressing eliminates the need to mix lubricants into the metal powder prior to compaction and thus eliminates the need to burn off the lubricant prior to sintering.
But the disadvantage is that the wet bag cold isostatic pressing process is cumbersome and cannot be compared with conventional production efficiency, so it cannot compete with conventional pressed powder metallurgy products in the market, mainly for the production of some large, complex shapes and small batches of powder metallurgical products.
2. Dry bags are cold pressed
Due to the slow efficiency of wet bag cold isostatic pressing, powder metallurgy manufacturers for isostatic pressing usually also have dry bag cold pressing, and the dry bag cold pressing bag is permanently installed in the pressure vessel. Fill the bag cavity with powder and seal it with a cover plate, release the pressure after applying pressure, uncover the cover plate, and take out the compact, which completes a production cycle. The dry bag cold press bag needs to be reused, so it needs to be of high quality and slightly thicker when it is manufactured. Although the production efficiency of dry bag cold isostatic pressing is much faster than that of wet bag cold isostatic pressing, when producing powder metallurgy products with relatively grooves, dry bag cold pressing is not as good as wet bag cold isostatic pressing.
The powder metallurgy products pressed by isostatic pressing are more uniform in density than conventional one-way pressing, and can also produce parts with higher diameters, grooves and thin-walled sections than conventional powder metallurgy, but the production speed is slower. Isostatically pressed powder metallurgy products are produced by enclosing the powder in a flexible bag and then immersing the bag containing the powder in a fluid to apply pressure to it.
Jiangsu High Industry on the research and development and production of high-performance polyurethane isostatic pressing molds. Through in-depth cooperation with many isostatic pressing equipment manufacturers and in-depth study of the industry, the developed isostatic pressing polyurethane mold series products have the characteristics of long service life, high precision, small deformation, easy demoulding, etc., and are widely used in ceramics, etc. Static pressing mould, cemented carbide isostatic pressing mould, rare earth permanent magnet material isostatic pressing mould, graphite isostatic pressing mould, etc.
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