Evaluation of wear performance of additively manufactured metal alloy samples

• Main Author: Lee, Tian Loke
• Other Authors: Liu Erjia
• Format: Final Year Project
• Language: English
• Published: 2017
• Subjects: DRNTU::Engineering::Mechanical engineering::Prototyping
• Online Access: http://hdl.handle.net/10356/70809
• Institution: Nanyang Technological University

Additive Manufacturing (AM) rose to become a top choice in manufacturing industry as it is able to provide flexibility in design of product. Complicated designs that are not achievable by conventional manufacturing methods can easily be produced by AM. Furthermore, AM can produce intricate parts with high accuracy which is highly sought after in the medical industry to produce top precision bio-implants. Hip implant is a common surgery and advances in technology have helped to shorten manufacturing process and at the same time improve the quality of implants significantly. AM techniques like Electron Beam Melting (EBM) help to fabricate customised implants in a shorter time period and with higher precision than before. This report aims to study the wear characteristic of AM manufactured samples to serve as a guide for choice of material to fabricate AM hip implants. Ti-6AI-4V (Ti64) and Co-Cr-Mo (CoCr) samples were fabricated using EBM which is a type of classification under powder bed fusion. There were 4 different samples built for Ti64 and CoCr respectively, each sample had a different thickness. There was also a cast sample individually for Ti64 and CoCr that was cut from a rod fabricated by traditional casting. In total there were 5 samples for each material. Hardness values of the samples were obtained using a Vickers hardness tester. A ball-on-disc tribometer was used to evaluate the tribology behaviour of the samples and coefficients of frictions (COF) were also obtained. The wear rates of the samples were derived through measurements of the wear areas of the wear tracks using a laser profilometer. Wear tracks were also analysed by a scanning electron microscope (SEM) to study the wear mechanism. The samples were etched and the microstructure was analysed using an optical microscope. Subsequently, the effect of friction, lubrication and hardness on the wear rates of samples with different thickness were studied.