Experimental study on the effect of varying focal offset distance on laser micropolished surfaces

Laser polishing of 3D printed mesoscale components

“…The effects of process parameters such as energy density [17][18][19], scanning speed [20] and step-over distance [21] on the quality of laser polished surfaces have been studied by numerous researchers, with the majority concluding that laser energy density has the strongest influence on resulting surface integrity [19]. Laser energy density is typically controlled by varying the focal offset distance (FOD) from the workpiece, which correspondingly alters the diameter of the beam.…”

“…Laser energy density is typically controlled by varying the focal offset distance (FOD) from the workpiece, which correspondingly alters the diameter of the beam. Chow et al [17] investigated laser micropolishing (LµP) of AISI H13 steel surfaces at FOD's of 1.3-2.9 mm. A decrease in surface roughness of up to 39.7% was achieved with a FOD greater than 2.2 mm.…”

Smoothing additive manufactured parts using ns-pulsed laser radiation

“…The laser fluence F per pulse can be adjusted by changing the laser spot diameter at the irradiated region which is controlled by the working position. This methodology has been already used by Mai and Lim [34] as well as Chow et al [25]. The focused laser beam has a spot diameter of approx.…”

“…For example, Perry et al showed a reduction of the average surface roughness Ra from 0.206 to 0.070 µm using a Nd:YAG laser source with 650 ns long pulses [24]. Also, Chow et al have indicated that the surface quality can be improved by adjustment of the focal offset position of the laser radiation [25]. Many other research studies concerning laser polishing have been published by Propawe and other researchers [26][27][28][29], reporting that the quality of the smoothing process can be controlled by diverse parameters such as the pulse duration, the laser power or the focal position.…”

“…The reached results up to now have shown that laser smoothing can be used to successfully compete with conventional polishing processes. However, only a few publications are available on laser smoothing of the innovative additive manufactured Scalmalloy ® or Titanium 64 substrates [16,[23][24][25]30], defining the main objective of the present research. In particular, the use of an industrial laser system providing pulses in the nanosecond range for the post-treatment process of AM materials has not been sufficiently researched.…”