On the influence of build orientation on the mechanical properties of direct metal laser sintered (DMLS) Ti-6Al-4V flexures

Abstract

This project was a cooperation between the TUDelft and Hittech. Hittech is a Dutch company that want’s to explore the latest technologies. The relative new techniques of additive manufacturing are becoming more mature and beneficial for businesses. One of the latest developments is Direct Metal Laser Sintering of titanium-alloy: Ti-6Al-4V, a material widely used in high-tech, high performance, medical, and flexure based applications. Flexures are beam shaped appliances that allow small displacements by bending the material, while constraining movement in other directions. In this project, Mechanical properties of the material are studied on the level of research and development. In particular the influence of build orientation is investigated by means of testing samples printed at 0° , 45° and 90°. Results should indicate the mechanical properties and whether build orientation should be considered during design of flexure based products. It was found that samples deviate in dimension from the design, and high surface roughness values were measured mainly in the 90° and 45° build orientation. Ultimate tensile strength shows small differences in between build orientations. Also the fatigue limit estimations according to Dixon-Mood shows difference in between build orientations and both show that the 0° build orientation is the strongest and most fatigue resistant. The results clearly show that build orientation should be accounted for when designing flexure based products for production with DMLS of Ti-6Al-4V. As the tests were performed on the level of research and development and also some inconsistency is found in the test results and further testing for reliability is recommended.