Metallic workpieces of diverse shapes having work surfaces which are deformed at the surface and adjacent sub-surface
layers by surface
impact from ultrasonic transducers employing freely axially moving impacting elements propelled and energized by a
transducer oscillating surface vibrating periodically at an ultrasonic frequency. The impacting elements are propelled in a random aperiodic and controlled
impact mode at different phases of the
periodic oscillation cycles. The
transducer may be portable and provides a series of mechanically interconnected stages having mechanical resonances harmonically related as a multiple of the primary ultrasonic frequency and have matched stage resistances under instantaneous loading when the
impact elements are driven by the
transducer oscillating surface into the surface of the workpiece. This mode of operation produces Q-factor amplification of the input ultrasonic power oscillator energy at the impact needles and high propulsion velocities making it possible to
machine metallic workpiece bodies to greater depths for compressing the
metal to increase
compressive strength of the workpiece work surfaces to substantially the ultimate material strength. The impact
machining is done at ambient temperatures.