Isostatic Presses Information
Isostatic presses are used for compressing powdered materials into shaped pre-forms or general products. There are two main types of isostatic presses; cold isostatic presses (CIP) that function at room temperature and hot isostatic presses (HIP) that function at elevated temperatures. Applications for these processes include consolidation of powdered metals, ceramics, carbides, composites, pharmaceuticals, carbon / graphite, ferrites, explosives, chemicals, foods, nuclear fuel or other materials into compact shapes. Cold pressed metals or ceramic powder compacts may require additional processing, such as sintering, to provide a finished part. Cold isostatic pressing is a compaction process by which powders are turned into include refractory nozzles, blocks, and crucibles; cemented carbides, isotropic graphite, ceramic insulators, tubes for special chemical applications, ferrites, metal filters, preforms, and plastic tubes and rods. The powder material is placed within a mold, then placed into the CIP processing chamber. A liquid medium, often an oil-water mixture, is pumped in and pressurized on all sides to create a uniform product. The pressure with a CIP chamber may reach as high as 100,000 psi. CIP applications Advantages of cold isostatic presses include the creation of product with uniform density, which leads to a reduction of internal stresses, eliminating cracks, strains and laminations. They also press products that have a higher “green strength” which allows for close tolerances, complex shapes, and better machinability. In addition, the CIP process is relatively inexpensive. Separate styles of cold isostatic presses are available for both industrial and laboratory applications. Specific CIP processes include wet bag processing (free molding), dry bag processing (fixed molding), and warm isostatic pressing (WIP).
Hot isostatic presses use an argon atmosphere or other gas mixtures heated up to 3000º F and pressurized up to 100,000 psi to process powders and other materials into dense preformed metals, plastics and ceramics. Hot isostatic presses function by introducing gas into the HIP furnace and simultaneously increasing the temperature and pressure to add density to the materials being processed. Typical HIP applications include processing high performance ceramics, ferrites and cemented carbides, net-shape forming of nickel-base super alloy and titanium powders, compacting of high-speed tool steel, diffusion bonding of similar and dissimilar materials, and eliminating voids in aerospace castings. They can also be used to remove defects from castings and heat-treat creep damaged products. As with CIPs, hot isostatic presses are available in small batch laboratory styles, as well as, industrial or plant varieties for larger production needs.