Effect of retaining ring slot designs and polishing conditions on slurry flow dynamics at bow wave

► Bow wave slurry film thickness was measured using ultraviolet enhanced fluorescence technique. ► Two polyetheretherketone (PEEK) retaining rings were tested under different polishing conditions. ► PEEK-1 generated thicker slurry film than PEEK-2. ► Film thickness increased with flow rate and ring pressure and decreased with sliding velocity for PEEK-1. ► Film thickness did not change significantly for PEEK-2.