Gas Atomization Processing Parameters for Tool Steel Powders
Gas atomization of tool steel powders requires maintaining melt superheat at 150°C above liquidus and gas-to-metal ratio between 1.8 and 2.5 to optimize yield.
Ultrasonic Sieving
Meaning
Mechanical separation technique applies high frequency vibrations to a mesh screen to prevent blinding and improve the throughput of fine metallic powders. The process of ultrasonic sieving uses an acoustic transducer to transmit energy across the entire surface of the sieve, which keeps the particles in motion and prevents them from wedging in the openings. This is especially useful for powders with a size below forty five micrometers where electrostatic forces and moisture can cause significant clumping.
By reducing the friction between the powder and the mesh, the system allows for a more accurate and efficient grading of the material. It is a standard method in quality control labs and production facilities for ensuring that powders meet strict size specifications.
Frequency Application
Vibration is generated by a power supply that converts standard electrical current into high frequency signals, typically in the range of thirty to forty kilohertz. These signals are sent to a transducer that is mechanically bonded to the sieve frame or the mesh itself. In an ultrasonic sieving system, the rapid oscillation of the mesh effectively breaks up agglomerates and pushes the fine particles through the openings.
Unlike traditional shaker sieves that rely on large mechanical movements, the ultrasonic method uses low amplitude vibrations that are less likely to damage fragile powder grains. The intensity of the vibration can be adjusted to suit the specific density and flow characteristics of different alloys.
Mesh Maintenance
Prevention of blinding is the primary reason why this technology is used in the processing of advanced metallic materials. Blinding occurs when particles that are just slightly larger than the mesh opening become stuck, eventually blocking the entire screen and stopping the flow. Ultrasonic sieving creates a continuous micro vibration that clears these trapped particles and keeps the screen open for longer periods.
This reduces the need for manual cleaning and extends the life of the expensive precision mesh. Because the screen stays clear, the accuracy of the separation is maintained throughout the entire batch, ensuring a consistent product for the end user.
Processing Rate
Throughput of a grading system is significantly increased when the mesh remains clear and the particles are actively dispersed by the acoustic energy. For many fine powders, the use of ultrasonic sieving can double or triple the amount of material processed per hour compared to conventional vibrating screens. This higher efficiency is vital for industrial scale powder production where time and yield are major factors in the overall cost.
The system can be integrated into automated production lines to provide continuous monitoring and sorting of the powder stream. Reliable performance in high volume environments makes this technology an essential part of the supply chain for additive manufacturing and metal injection molding.