Inert Gas Atomization Basics for Powder Tool Steels
Inert gas atomization of tool steels requires precise superheat control, supersonic argon nozzles, and closed-loop gas recycling to yield dense spherical powders.
Carney Funnel ASTM B964
Meaning
Testing apparatus designed to measure the flow rate of metal powders that do not move freely through a standard hall funnel due to their surface characteristics or particle size. Utilizing the carney funnel astm b964 allows technicians to characterize materials that would otherwise bridge or clog in smaller orifices during density or flow testing. The device features a larger exit diameter which provides a more consistent discharge for powders with irregular shapes or high internal friction.
This measurement is essential for materials used in thermal spray applications or certain powder metallurgy processes where flow consistency is required for part quality.
Aperture Design
Geometry of the device is similar to a hall funnel but features a wider discharge opening of five millimeters instead of two and a half millimeters. When using the carney funnel astm b964, the increased diameter reduces the likelihood of mechanical interlocking between the particles as they transition from the conical body to the exit. This modification allows for the testing of powders that are considered non-free-flowing by other standards.
The internal surfaces are polished to a high finish to minimize the influence of wall friction on the resulting flow time. If a powder still fails to flow through this larger opening, it is classified as non-flowable and requires different characterization methods.
Flow Characterization
Measurement involves timing how long it takes for a fifty-gram sample of material to pass through the orifice into a receiving vessel. The carney funnel astm b964 provides a repeatable metric that correlates with the performance of the powder in industrial feeding systems. A slow flow time indicates that the particles have high surface area or rough textures that impede movement.
Conversely, a rapid flow suggest that the powder has been processed to improve its spherical nature or reduce the moisture content. Engineers use this data to adjust the hopper angles and feeder settings in a manufacturing plant.
Density Correlation
Calculating the mass per unit volume of a powder using this funnel provides a variation of the apparent density measurement for coarser or more irregular materials. The carney funnel astm b964 is used in conjunction with a twenty-five cubic centimeter cup to determine how the material packs under gravity. This value is generally lower than the tap density because it does not include any mechanical agitation to settle the particles.
Knowing this figure helps in the design of shipping containers and storage silos where volume is a constraint. It also informs the calculation of the fill factor for molds used in high-pressure compaction. The resulting data helps maintain the consistency of the final sintered products.