A paper by Jantzen et al. in 2018 compared CO2 snow cleaning compared to ultrasonic and high speed air jet cleaning of small parts with sub-millimeter features.  The parts tested were an external spur microgear (metal, 0.4 mm, 17 teeth), an internal spur microgear (metal, 0.08 mm, 254 teeth), a brass nut (M4), and a ceramic bore (Y-TZP, Ø 3 mm, height 6 mm).  Contamination included aluminum granulates, alumina powder (400 mesh), titanium oxide power, and silicon carbide.  Average particle sizes were in the 20 to 50 micrometer range with a large spread from the average, both larger and smaller.  

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Overall cleaning results from 72 samples indicated CO2 snow cleaning showed the highest cleaning efficiency
in comparison with the high-speed air jet and ultrasonic cleaning.  CO2 snow removed 95 % of the contamination on average, while ultrasonics had 88 %, and high speed air had 74 %.  

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Overall, for parts with complex geometries, CO2 snow cleaning offers a positive advantage.

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see:

Jantzen, Stephan, Thomas Decarreaux, Martin Stein, Karin Kniel, and Andreas Dietzel. "CO2 snow cleaning of miniaturized parts." Precision Engineering 52 (2018) 122-129

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