Spatter and hole taper formations are two quality problems often encountered during laser percussion drilling of metallic materials. Researchers and manufacturers alike are actively seeking ways to either prevent or control these two inherent defects. This current work presents the combined use of a specially developed anti-spatter composite coating (ASCC) and a hole taper control method termed as Sequential Pulse Delivery Pattern Control (SPDPC). The ASCC is based on a mixture of ceramic particles and silicone elastomer, applied on the workpiece surface prior to laser drilling. The SPDPC involves the alteration of the overall delivery pattern during a pulse train required to drill a through-hole. This work has shown that the combined use of the ASCC and SPDPC was successful in preventing spatter whilst generating through-holes with good overall parallelism in Ni alloy sheet during Nd:YAG laser percussion drilling. The fundamental effects and mechanisms involved in the ASCC and SPDPC techniques are also discussed.

Topics
Metallic materials, Lasers, Polymers, Ceramics
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