Due to the increase in the life expectancy of world’s population, health care demands in terms of quality and accessibility are higher than ever before. Concerning the manufacturing of medical devices, the development of new biomaterials, new manufacturing methods and techniques have always been on researchers focus. In the development of a medical device, the choice of the proper material to be used is of the most importance, since its ability and capacity to fulfil the expected function will determine the success of the medical device itself. This work aims to do a review of those that are the most commonly used biomaterials. After an explanation on what are biomaterials and what defines them, a more in-depth approach is presented to each of the four major types of biomaterials: metal, polymer, ceramic, and composites, where their main characteristics and preferred applications in the area of medical devices are described.
Titanium alloys for their characteristics have acquired a prominent position in numerous industrial applications. Due to its properties, such as high resistance to corrosion, reduced density, high specific strength, and low Young’s modulus, titanium alloys became indispensable as a biomaterial with high use in medical devices, with special emphasis in the area of orthopedics. Problems associated with its manufacturing by conventional machining processes, such as milling, turning, and drilling are well known and studied. Its low thermal conductivity, high chemical reactivity, high hardness at high temperatures make it classified as difficult to machine material. Despite the already extensive knowledge about machining titanium alloys problems, and the constant technological development to overcome them, it is not yet possible to machine this material like other metals. This work is based on research and review papers from Scopus and Scholar from 2010 to 2020 and addresses the main issues related to the machining of titanium alloys used in medical devices manufacturing and current solutions adopted to solve them. From the research consulted it was possible to conclude that it is consensual that for milling, turning, and helical milling cutting speed can reach up to 100 m/min and up to 40 m/min in drilling. As for feed rate, up to 0.1 mm/tooth for milling and helical milling and up to 0.3 mm/rev for turning and 0.1 mm/rev for drilling. Also, that Minimum Quantity Lubrication is a valid and efficient solution to mitigate titanium alloys machining problems.
In the manufacturing of a medical device, may occur the need to make a hole with a specific function. Among current methods, conventional drilling (CD) referred in this work as drilling (D) and helical milling (HM) are two options with different potential.When making the hole, it is important to choose the most suitable method to obtain the desired geometry and ensure the functionality of the device. This work aims to analyze surface parameters as, arithmetic average height (R a ), the maximum height of the profile (R t ), the average peak to valley height (R z DIN), chip formation and the geometric deviation of holes obtained by the previously referred manufacturing processes. The specimens, with cylindrical geometry, were made of titanium alloys, Ti-6Al-4V and Ti-6Al-7Nb, currently used in the manufacture of medical devices. For this purpose, holes were made in a machining centre with different feed rate (F) for both methods and in the value of vertical step (a p ) in HM. The results obtained demonstrate that, at lower F and a p , HM presents better results. The Ti-6Al-7Nb alloy presents better roughness results compared to Ti-6Al-4V, validating it as a material able to be used in medical devices according to the fact that, a lower roughness is associated with higher corrosion resistance and fewer fatigue problems derived from it in components. By the work carried out, can be concluded that the roughness values obtained in HM are lower to those obtained by D making HM as a better option in hole making.
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