Effect of Fiber Laserprocess Parameters on Texture Dimensions Fabricated on Cast Iron Piston Ring Segments

This study investigates the effect of various fiber laser process parameters on texture diameter, depth and surface roughness of circular shaped textures fabricated on the commercially cast iron piston ring segments. Piston ring segments with hardness 410 HV, Young’s Modulus of 250 Gpa and surface roughness of 0.482 µm were used for the experimentation. The fiber laser system (Marko Laser, Germany), was used for the fabrication of textures on the cast iron segments having specifications like power of 20W, wavelength of 1062nm, maximum frequency 200KHz, maximum speed range of 15000 mm/s. The laser frequency, power, speed and number of loops are the input parameters which were varied to find its effect on the texture dimensions. The approximate target values to be achieved for circular texture dimensions are texture diameter of 100µm (bilateral tolerance of 10µm), texture depth of 20µm (bilateral tolerance of 3µm) and texture surface roughness of 3µm (bilateral tolerance of 0.5µm) respectively. A confocal microscope with three dimensional surface profiler was used to measure the surface topography of the textured surfaces. It has been observed that with increase in laser power initially texture diameter has been reduced but found to be increased for the maximum power condition, while dimple depth and surface roughness of the textures found to be increased gradually. Also with increase in frequency has not a significant effect on the texture diameter but the texture depth and surface roughness has been enhanced drastically. In the similar way with increase in the laser speed and number of loops, initially there was decrease in the texture dimensions but as the speed and number of loops increased the texture dimensions also has a slight enhancement on it. It may be concluded that laser power and laser frequency has a significant impact on the texture dimensions as compared to laser speed and number of loops. Also it can be summarized that for achieving the targeted values of the texture dimensions like texture diameter, texture depth and texture surface roughness on the piston ring surface the laser power of 12W, 8W and 8W, laser frequency of 25 KHz, 25 KHz and 20 KHz, laser scan speed of 170 mm/sec, 140 mm/sec and 110 mm/sec and number of laser loops of 5, 4 and 2 may be used respectively. KEYWORDS: Confocal Microscope; Fiber Laser; Laser Power; Laser Texturing; Texture Dimensions