Investigation of hole quality in drilling of parts produced with hole features by additive manufacturing

Although additive manufacturing (AM) is increasingly used today, traditional machining such as drilling is generally needed to meet the application requirements due to its cost when high production numbers are required and limited material and printing sizes. This study predicted that it would be more appropriate to drill the holes to the desired diameter size after the Ti6Al4V alloy, designed with pre-holes, primarily due to its advantage to AM production costs, was produced by the Selective Laser Melting method. Deviation from mean diameter after AM; 0.179 mm, deviation from mean circularity; 0.0851 mm, deviation from mean cylindricality; 0.1113 mm results in diameter deviation after drilling with an improvement of approximately 98% in all values; 0.032 mm, deviation from circularity; 0.0084, deviation from cylindricality; 0.0134 mm. Increases in cutting forces in uncoated tools affected the hole quality negatively. Increasing cutting forces increased the deviation from diameter, deviation from cylindricality, and deviation from circularity. Better values were obtained in coated tools. With the study, it has been revealed according to the evaluation criteria that pre-drilling can be advantageous instead of full-hole drilling. The study determined that there is a sensitive relationship between the pre-drilled hole center and the drill center coming to the same point during drilling. Keywords: Additive Manufacturing, Hole Quality, Pre-drilled, Selective Laser Melting, Ti6Al4V