Cold Isostatic Pressing Cycles
The total cycle time can range from less than one minute for highly automated dry bag processes to tens of minutes for wet bag processes.
Insert compact: The mold that has been filled with powder to be pressed is sealed and placed in the partially filled vessel. This causes the water level in the vessel to rise.
Fill and vent: The upper closure is installed and locked. Water is added to the vessel at low pressure through a fill and drain system to vent air through a valve in the upper closure. All air remaining above the fluid level must be removed since air is highly compressible and would consume great quantities of energy before the vessel reaches operating pressure.
Pressurize: After all air has been vented, the high-pressure-pumping system pressurizes the water to the operating pressure. Water is added during pressurization to equal the amount of volume reduction of the powder being pressed and to compensate for the compressibility of water at these pressures. Pressurization times are an important consideration in total system-cycle time and are a function of the pumping system flow rate. Faster pressurization rates require more expensive pressurization systems. The maximum desired pressure is usually maintained for no longer than a few minutes since particle deformation is not time dependent.
Depressurization: During depressurization, the volume of water that was added because of the compressibility of the powder and water is expelled from the vessel. The simplest decompression control consists of hand-operated depressurization valves. There are also sophisticated automatic depressurization systems capable of almost any decompression profile to help eliminate compact breakage that may occur by too rapid depressurization.
Remove compact and drain system: The mold is removed from the pressure vessel. Molds are usually washed and dried prior to opening. Part handling operations can be done manually or automated for production applications.
