Investigation of Coatings, Corrosion and Wear Characteristics of Machined Biomaterials through Hydroxyapatite Mixed-EDM Process: A Review

Together, 316L steel, magnesium-alloy, Ni-Ti, titanium-alloy, and cobalt-alloy are commonly employed biomaterials for biomedical applications due to their excellent mechanical characteristics and resistance to corrosion, even though at times they can be incompatible with the body. This is attributed to their poor biofunction, whereby they tend to release contaminants from their attenuated surfaces. Coating of the surface is therefore required to mitigate the release of contaminants. The coating of biomaterials can be achieved through either physical or chemical deposition techniques. However, a newly developed manufacturing process, known as powder mixed-electro discharge machining (PM-EDM), is enabling these biomaterials to be concurrently machined and coated. Thermoelectrical processes allow the migration and removal of the materials from the machined surface caused by melting and chemical reactions during the machining. Hydroxyapatite powder (HAp), yielding Ca, P, and O, is widely used to form biocompatible coatings. The HAp added-EDM process has been reported to significantly improve the coating properties, corrosion, and wear resistance, and biofunctions of biomaterials. This article extensively explores the current development of bio-coatings and the wear and corrosion characteristics of biomaterials through the HAp mixed-EDM process, including the importance of these for biomaterial performance. This review presents a comparative analysis of machined surface properties using the existing deposition methods and the EDM technique employing HAp. The dominance of the process factors over the performance is discussed thoroughly. This study also discusses challenges and areas for future research

A conceptual framework to support decision-making in remanufacturing engineering processes

Remanufacturing is a promising industrial activity where products and materials are upgraded and considered for at least another life cycle. In addition to being an environmentally conscious action, remanufacturing has the potential to support circular economy within which significant profit opportunities exist. However, high levels of uncertainty can be experienced during, before and after remanufacturing. This makes its planning stochastic and hard to control. As each component or product is different, with for example high levels of geometrical variation; they may require a unique strategy and process planning. To aid this process, a conceptual decision making framework to support process planning of remanufacturing engineering processes (REP) is proposed. Quality Function Deployment (QFD) method is employed to support the proposed framework (hereafter referred to as REP-QFD). The application of the QFD based methods rely heavily on inputs from experts, in the form of their experience and knowledge. The paper considers how the proposed framework can be engineered with the aim to substantially reduce this reliance on experts and their expertise. The term “Engineering” here reflects the study’s focus on technical decisions at the reconditioning stage. To further support the framework a taxonomy of metal manufacturing/remanufacturing processes is also developed