Cavitation Abrasive Surface Finishing & Peening (CASF): A New Method for Post Process Cleaning, Smoothing and Peening Complex Shapes of AM Parts
Additive manufacturing technologies produce complex shapes of metal parts. Traditional methods for surface finishing, such as hand working with rotary tools, hammer & chisel, tumbling, grit blasting, laser ablation and chemical milling are often applied to remove the unwanted leftover artifacts from the surface. These processes can result in a significant loss of material & fatigue properties and have relatively high cost, cause quality variations and add long flow time.
A brief history of CASF development based on biological sea creatures will be provided, along with recent advancements that have enabled the surface finishing of interior/hidden passageways for AM parts. CASF is an alternative technology for both conventional subtractive mechanical finishing and chemical acid based methods that makes use of imploding water vapor bubbles to produce violent shock waves of kinetically energized abrasives for finishing part surfaces. Recent tests of CASF have resulted in the surface roughness average of as-built titanium AM laser powder bed fusion parts being improved from an Ra of 20 µm or worse down to 4 µm and better.
Additional Technical Discussion Points for CASF:
- Circuitous internal passageway surfaces can be cleared of debris, smoothed and peened.
- Build structures can be quickly blown off, including tough stem trunks.
- Compressive residual stresses that approach those achieved by shot peening are imparted for improved fatigue life.
- Inert water and conventional abrasives are used. No hazardous materials are utilized. Chemical waste is not generated.
- CASF has been integrated into fully automated CNC machines that yield fast, precision and consistent results.