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


Laser micropolishing (LμP) is an innovative part-finishing process that reduces machining roughness by melting a thin layer of material on the micromilled surface using a focused laser beam. The quality of the final polished surface is dependent upon the part material, initial surface topography and roughness, and the energy density of the beam. The focal offset distance (FOD) is one critical parameter that controls the amount of energy delivered to the workpiece. The impact of varying the FOD on final laser-polished surface quality is investigated by performing a series of experiments on carefully prepared AISI H13 test samples with known initial surface roughness and waviness due to the milled track periodicity. Three well-defined polishing regimes were observed when adjusting the FOD for a Q-switched Nd/YAG LμP system between 1.3 and 2.9 mm. Given the same initial micromilled surface geometry, each LμP regime (i.e., short FOD, <1.8 mm; long FOD, >2.2 mm; and intermediate FOD) reduced the surface roughness and periodic waviness in a distinct manner. For a micromilled sample with a 33-μm periodicity, the LμP with FOD of >2.2 mm was determined to be the most effective regime by improving surface quality by 39.7 %. The affects of repetitive exposure to the beam and increasing the applied laser power on improving surface quality are also investigated for the 3 LμP regimes.

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  1. 1.

    Willenborg E, Wissenbach K, Poprawe R (2003) Polishing by laser radiation. In: Proceedings of the Second International WLT-Conference on Lasers in Manufacturing, Munich, Germany, pp. 297–300

  2. 2.

    Willenborg E (2008) New developments in polishing with lasers. Laser Tech J 5(3):72

  3. 3.

    Ukar E, Lamikiz A, López de Lacalle LN, del Pozo D, Arana JL (2010) Laser polishing of tool steel with CO2 laser and high-power diode laser. Int J Mach Tool Manuf 50:115–125

  4. 4.

    Dadbakhsh S, Hao L, Kong CY (2010) Surface finish improvement of LMD samples using laser polishing. Virtual Phys Prototyp 5(4):215–221

  5. 5.

    Nusser C, Wehrmann I, Willenborg E (2011) Influence of intensity distribution and pulse duration on laser micro polishing. In: Lasers in Manufacturing 2011—Proceedings of the Sixth International WLT Conference on Lasers in Manufacturing. Physics Procedia 12(1): 462–471

  6. 6.

    Perry TL, Werschmoeller D, Li X, Pfefferkorn FE, Duffie NA (2009) Examination of selective pulsed laser micropolishing on microfabricated nickel samples using spatial frequency analysis. J Manuf Sci Eng 131:1–9

  7. 7.

    Perry TL, Werschmoeller D, Duffie NA, Li X, Pfefferkorn FE (2009) The effect of laser pulse duration and feed rate on pulsed laser polishing of microfabricated nickel samples. J Manuf Sci Eng 131:1–7

  8. 8.

    Perry TL, Werschmoeller D, Li X, Pfefferkorn FE, Duffie NA (2009) Pulsed laser polishing of micro-milled Ti6Al4V samples. J Manuf Process 11:74–81

  9. 9.

    Mai TA, Lim GC (2004) Micromelting and its effects on surface topography and properties in laser polishing of stainless steel. J Laser Appl 16(4):221–228

  10. 10.

    Chow MTC, Bordatchev EV, Knopf GK (2012) Impact of initial surface parameters on the final quality of laser micro-polished surfaces. In: Maher MA and Resnick PJ (eds) Micromachining and microfabrication process technology XVII. SPIE: 824809-824809-10

  11. 11.

    Chow MTC, Hafiz AMK, Tutunea-Fatan OR, Knopf GK, Bordatchev EV (2010) Experimental statistical analysis of laser micropolishing process. Int Symp Optomechatronic Technol 1–6, doi:10.1109/ISOT.2010.5687316

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Correspondence to George K. Knopf.

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Chow, M.T.C., Bordatchev, E.V. & Knopf, G.K. Experimental study on the effect of varying focal offset distance on laser micropolished surfaces. Int J Adv Manuf Technol 67, 2607–2617 (2013).

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  • Laser micropolishing
  • Focal offset distance
  • Surface roughness
  • Surface waviness