Spatter-free laser percussion drilling of closely spaced array holes

Abstract Spatter is one of the inherent defects commonly associated with holes produced with laser drilling. This work reports on a method of spatter prevention, workable for a wide range of process parameters. The method is based on the application of a specially developed anti-spatter composite coating (ASCC), containing a mixture of ceramic filler particles embedded in a silicone elastomer matrix, on the workpiece surface prior to laser percussion drilling. Experiments were conducted using a fibre-optic delivered 400 W Nd:YAG laser for the drilling of closely spaced through holes (2 mm hole pitch) in Nimonic 263 alloy sheets. The work revealed that the ASCC effectively prevented the deposition of spatter such that laser drilled holes were produced whilst maintaining the as-received surface characteristics of the Nimonic 263 alloy for all the assist gases tested (O 2 , air, N 2 and Ar). The process characteristics and spatter prevention mechanism associated with the use of the ASCC have been investigated using optical microscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis, contact angle analysis and high-speed photographic imaging. Comparative studies were also made with the case of uncoated laser drilling.

[1]  W. Zisman.  INFLUENCE OF CONSTITUTION ON ADHESION , 1963 .

[2]  J. Murthy,et al.  A novel anti-spatter technique for laser drilling: Applications to surface texturing , 1997 .

[3]  W. Zisman,et al.  CONSTITUTIVE RELATIONS IN THE WETTING OF LOW ENERGY SURFACES AND THE THEORY OF THE RETRACTION METHOD OF PREPARING MONOLAYERS1 , 1960 .

[4]  T. Chow.  Wetting of rough surfaces , 1998 .

[5]  W. Betteridge.  The nimonic alloys , 1959 .

[6]  C. Harper.  Handbook of Plastics, Elastomers, and Composites , 1996 .

[7]  Lin Li,et al.  Diode laser modification of ceramic material surface properties for improved wettability and adhesion , 1999 .

[8]  M. J. Jaycock,et al.  Chemistry of interfaces , 1981 .

[9]  A. Kar,et al.  Two‐dimensional model for material damage due to melting and vaporization during laser irradiation , 1990 .

[10]  Thomas Young,et al.  An Essay on the Cohesion of Fluids , 1800 .

[11]  Song Wulin,et al.  Effect of Ni content on cracking susceptibility and microstructure of laser-clad FeCrNiBSi alloy , 1996 .

[12]  Lin Li,et al.  Effects of assist gas on the physical characteristics of spatter during laser percussion drilling of NIMONIC 263 alloy , 2000 .

[13]  D. Bäuerle.  Laser Processing and Chemistry , 1996 .

[14]  Mark S. M. Alger,et al.  Polymer Science Dictionary , 1989 .

[15]  M. Owen.  Siloxane surface activity , 1990 .

[16]  B. Yilbas.  Study of liquid and vapor ejection processes during laser drilling of metals , 1995 .

[17]  Egon Matijević,et al.  Surface and Colloid Science , 1971 .

[18]  Bekir Sami Yilbas,et al.  Liquid ejection and possible nucleate boiling mechanisms in relation to the laser drilling process , 1997 .

[19]  A. Matsunawa,et al.  The role of recoil pressure in energy balance during laser materials processing , 1997 .

[20]  D. Low,et al.  The influence of assist gas on the mechanism of material ejection and removal during laser percussion drilling , 2000 .

[21]  K. Richter,et al.  Laser beam drilling applications in novel materials for the aircraft industry , 1997 .

[22]  Walter J. Murphy,et al.  ADVANCES IN CHEMISTRY SERIES: Numbers 15 and 17 Demonstrate Rapidly Crowing Interest in Documentation; International Conference To Be Held in 1958 , 1956 .