Ultrasonic Cavitation Peening

Ultrasonic cavitation peening produces shallow depths of peening ideal for components of thin section. This shallow depth is ideal for improving the fatigue life of components with a thin cross-section.

Cavitation Peening Process

1. After submerging the component in deionized water, the process creates microscopic bubbles beneath a pad during the ultrasonic rarefication stroke.
2. By holding a fixed vertical offset, the CNC controller precisely translates the probe tip over the surface area to be peened.
3. When the probe tip moves up at ultrasonic frequency, cavitation bubbles form.
4. When the probe tip moves downward, bubbles on component surface collapse non-symmetrically, generating a high intensity pressure burst that peens the component surface.
5. This asymmetric collapse creates an intense local water jet resulting in plastic deformation on the surface.
6. Because the bubbles are small, the depth of plastic response is on the order of 100 microns (0.004 inches)[GC1]
7. When the probe tip moves up at ultrasonic frequency, cavitation bubbles form.

Benefits of Cavitation Peening

• Shallow depth of residual compressive stress for thin delicate components that are required in operation to oscillate or cycle.
• High cycle, low stress situations (HCF) in a deteriorating surface environment.
• Enables peening of components too thin for shot or laser peening.
• Ultra-clean processing enables applications where contamination cannot be tolerated.
• CNC process control results in high processing repeatability and quality control.

Industries That Utilize Cavitation Peening

Ultrasonic peening is ideal for peening depts of 100 microns and shallower, that is for components of very thin cross section. The depth of penetration of any peening process is directly related to the impingement spot size. Because ultrasonic peening bubbles are microscopic in size, their penetration is equally shallow. In shot peening, the shot balls are typically submillimeter in size and thus the penetration is submillimeter to one millimeter in depth. In high energy laser peening where spot sizes scale from multi-millimeter to centimeter in size the penetration depth scales equally.

• Electronics
• Automotive
• Aerospace
• Automated control by small and miniature component

Ultrasonic Cavitation Peening – Unique Attributes

• No solid objects touch the piece being peened
• Increase of surface roughness is less than shot or laser peening
• Water used contains metal and metal oxide which can be recycled
• Low cost to perform
• Only requires one step
• Improves deep and narrow notch properties

With ultrasonic, shot and laser peening technology, CW thus offers capability to meet specific needs from delicate electronic components of sub-millimeter scale to intermediate and to very large and thick structures.

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