A Method to Proof Test Ceramic and Glass Balls that Detects Very Small Manufacturing Flaws

An acoustical mechanical test method prescribes compressing brittle balls in spherical conforming opposing platens producing equatorial bulging, tensile stresses, and resulting in crack or flaw growth with emissions of acoustical sounds for direct identification of brittle balls having a flaw exceeding a maximum allowable size, such as flaws in silicon-nitride balls used in hybrid bearings as well as conventional steel ball bearings.