Influence of the Velocity and the Number of Polishing Passages on the Roughness of Electrolytic Plasma Polished Pipe Inner Surfaces

Electrolytic plasma polishing (EPP) is an emerging technology for polishing, cleaning, deburring and smoothing of free-formed metal surfaces. The electrolytic plasma polishing of outer metal surfaces is state-of-the-art, whereas the polishing of pipe inner surfaces has only recently been reported by the authors. A prototype system and first experimental results were presented. It was found in the previous study that the average surface roughness Sa reaches a range from 0.065 µm to 0.090 µm. The current study systematically investigates the influence of the velocity v as well as the number n of polishing passages on the average surface roughness Sa . The polishing of the pipe inner surface and weld seam are considered separately. The results show that the average roughness Sa is mainly dependent on the effective polishing time t e p t of the polishing process. The average surface roughness Sa of the pipe inner surface can reach a range from 0.030 µm to 0.034 µm starting from an initial surface roughness S a 0 of 0.719 µm, whereas the average surface roughness Sa of the weld seam can reach a range from 0.088 µm to 0.096 µm starting from an initial surface roughness Sa 0 of 0.282 µm. These ranges are achieved after an effective polishing time of approximately 25 s for both the inner pipe surface and the weld seam.