Investigation of the effects of laser polishing parameters on the surface quality improvement of additively manufactured Ti-6Al-4V material

Additive manufacturing methods provide the possibility of producing complex geometric parts that are challenging or even impossible to manufacture using traditional methods. However, parts produced using additive manufacturing often have lower surface qualities compared to those made using traditional methods. Therefore, parts requiring high surface quality undergo additional processes after manufacturing. Laser polishing is one of the most commonly used methods today to improve the surface quality. In this thesis, additively manufactured Ti-6Al-4V samples were subjected to laser polishing in an open-air environment, and the relationship between surface roughness values and the parameters used during the experiments was investigated using design of experiments methods. Starting with an initial surface quality of Ra=8.1 μm, 120 Ti-6Al-4V samples were processed using 6 different laser powers, 5 different scanning speeds, and 4 different scan overlap ratios, achieving a 50.37% improvement in surface quality with a final Ra value of 4.02 μm. ANOVA analyses using design of experiments methods were conducted to examine the effects of process parameters on the results. These analyses revealed that the parameters with the most significant impact on the outcome were laser power and scan overlap ratio. In the final step, regression prediction equations were established. These equations, with consistency rates above 90%, allow for obtaining estimated results without the need for experimentation for out-of-sample parameters.