ANALYSIS OF GEOMETRICAL CHARACTERISTICS OF PULSED ND:YAG LASER DRILLED HOLES IN SUPERALLOY NIMONIC 263 SHEETS

Owing to their excellent mechanical and physical characteristics, superalloys are the most suitable material for use in hot sections of aircraft engines. Thousands of holes need to be drilled in constructive parts of machines, with laser technique emerging as the most effective. Laser drilling has been used to produce small diameter, accurately positioned holes, with little damage in regions around them, and in various materials. Effective laser employment of drilling of high quality holes for critical applications highly depends on correct selection and optimization of laser drilling parameters. In this work, the holes were drilled by a pulsed Nd super(3+): YAG laser, with rnasimurn average power of 160 W, in superalloy Nimonic 263 sheets, thickness 0,7 mm and 1,2 mm. The holes were observed by optical and scanning electron microscope. Geometrical characteristics of laser drilled holes that depend on laser parameters were investigated and analysed. The aim of this investigation was to find optimal laser parameters which would produce as much as possible regular holes.Original Abstract: Zbog svojih odlicnih mehanickih i fizikalnih znacajki, superlegure su najpogodniji materijal za uporabu u toplim sekcijama zrakoplovnih motora. U konstrukcijskim dijelovima strojeva treba izbusiti tisuce rupa, za sto se kao najucinkovitija pokazala laserska tehnika. Busenje laserom koristi se za proizvodnju malih promjera, tocno pozicioniranih rupa, s malim ostecenjima u podrucju oko njih i u razlicitim materijalima. Ucinkovita uporaba lasera za busenje rupa visoke kvalitete za kriticne primjene uvenke ovisi o ispravnom izboru i optimiranju parametara busenja laserom. U ovom radu, rupe su izbusene Nd super(3+):YAG impulsnim laserom, uz maksimalnu prosjecnu snagu od 160 W, u limovima superlegure nikla Nimonic 263, debljine 0,7 mm i 1,2 mm. Rupe su promatrane optickim i skenirajucim elektronskim mikroskopom. Istrazene su i analizirane geometrijske znacajke laserski busenih rupa, koje ovise o parametrima lasera. Cilj ovog istrazivanja bio je pronaci optimalne parametre lasera koji bi omogucili sto pravilnije rupe.