Percussion drilling with laser: hole completion criterion

Abstract

The criterion for ensuring formation of a through hole is an important aspect of laser drilling. Close observation of the process has indicated that drilling of the substrate is achieved in six successive microstages. The stages have been time resolved and the behaviour of laser induced plasma (LIP) during the microstages of drilling has been carefully examined. The LIP behaviour during the percussion laser drilling has been explained with the help of the contemporary understanding of plasma. This paper proposes a drilling completion criterion that is based on the behaviour of LIP during laser percussion drilling of SUPERNI 263A with a Nd-doped yttrium aluminium garnet laser. The completion of formation of a hole is marked by the momentarily increased luminescence of the plasma plume emanating from the laser beam exit side of the workpiece during drilling. The criterion has been experimentally verified. The criterion is versatile and can help in augmenting productivity during manufacturing.

Laser treatments of Nimonic 263 nickel-based superalloy

“…Petronić i saradnici [14] su analizirali uticaj parametara lasera na geometrijske karakteristike rupa bušenih u limovima superlegure nikla debljine 0.7 i 1.2 mm. Panday i saradnici [15] su predložili kriterijum bušenja koji se zasniva na ponašanju plazme stvorene laserom tokom procesa bušenja. Salonitis i saradnici [16] su predstavili teoretski model zasnovan na pretpostavci da tokom svakog laserskog pulsiranja, konačna zapremina materijala bude uklonjena.…”

“…Stepen suženja se smanjuje sa povećanjem debljine materijala [15]. Stepen suženja može da se kontroliše promenom trajanja impulsa, energijom impulsa, brojem impulsa ili različitim dizajnima optičkog sistema.…”

Comparison of bending fracture strength of silicon after ablation with nanosecond and picosecond lasers

“…Lasers with pulse durations of some tens of nanoseconds have been commonly used in research on drilling using laser ablation [4,[8][9][10][11]. Lasers with pulse durations ranging from a few picoseconds to femtosecond are currently under development; these lasers are referred to as ultra-short pulse lasers, and research using these lasers for laser ablation drilling has been conducted [12][13][14][15][16][17][18].…”

Real-Time Breakthrough Detection for Laser Drilling Based on Coaxial Visual Sensing Technology

“…Monitoring the condition used to determine the laser drilling time required for producing a hole is necessary for automating the process. However, it is therefore impossible to check the completion of drilling by visual monitoring of the hole size as is possible in the case of conventional drilling [1].…”