Manufacturing Of Medical Implants Research Articles

Magnetic-abrasive machining in manufacturing of medical implants

Despite the rapid development of new biocompatible medical materials, the question of an optimal mechanical processing of implants surfaces remains a major challenge. Surface integrity of sliding pair surfaces in implant joints is the key to prostheses long-term usage. In this article, a free form finishing process – magnetic-abrasive machining (MAM) – is presented as an alternative for machining implant joints. MAM shows a positive impact on surface integrity of a spherical workpiece made of cobalt-chromium alloy. Comparing to the initial turned surface, the roughness is reduced by more than 50% and compressive residual stresses are increased by more than 10%.

Investigations on achievable surface quality in milling of Ti-35Nb-7Zr-5Ta alloy

ABSTRACT β-type Titanium (Ti) alloy possesses less Young’s Modulus (E), which is significant for manufacturing of medical implants, since it reduces stress shielding effect. In this work, surface quality analysis on Ti-35Nb-7Zr-5Ta(TNZT) alloy was carried out to reveal the osseointegration characteristics. TNZT alloy was fabricated by vacuum arc melting followed by homogenization process. Microstructure analysis with X-ray diffraction spectroscopy study revealed the formulation of body-centered cubic structure in the TNZT alloy. Further high speed milling was carried out to analyze the impact of process variables on surface quality. Parameters include axial depth of cut (ap), cutting velocity (vc), and feed/tooth (fz) are taken into consideration. In general, implants are miniature in size; hence, Carbide flat end mill cutter size of 2 mm is used for investigation. 27 slots are generated under mist cooling condition by using factorial experimental design approach. Surface characteristics and morphology of machined region were examined to discover biocompatibility. It is observed that ‘ap’ and ‘vc’ significantly affect surface quality and lowest Ra of 0.422 µm was observed. It is well within the allowable value between 1 and 1.5 µm for better osseointegration. It is also revealed that microparticle deposition and groove formation intensifies when ‘ap’ is higher at 200 µm.

Mechanical Properties of Titanium Nickelide–Tantalum–Chitosan Composite Material

A biocompatible material characterized by gradient structure titanium nickelide–tantalum–biodegradable polymer layer was designed for the manufacture of medical implants. The mechanical characteristics of the material and components were studied. The structure and composition were determined by SEM and Auger electron spectroscopy. The formation of surface layers does not significantly affect the mechanical characteristics of the support; high adhesion between the layers and the support is observed.

Development of technology of microplasma spraying for the application of biocompatible coatings in the manufacture of medical implants

Development of technology of microplasma spraying for the application of biocompatible coatings in the manufacture of medical implants

Design and Machining of the Femoral Component of Total Knee Implant

Manufacturing of medical implants constitutes always a challenge, regarding the constraints involved for these applications, e.g. need for suitable materials or appropriate dimensional tolerances. The aforementioned pose also challenges for the machining process itself, regarding the appropriate machining conditions and machine tool setup and so it is considered as a subject of interest. In the present work, the manufacturing process for knee implants, especially for the femoral component of this type of implants, is discussed, encompassing all the stages from design and planning of each step of the process up to actual machining of the implant component. Finally, the surface quality of the implant after finishing process is assessed for each of the three different finishing processes applied, in order to determine the suitable machining parameters required.

Women with silicone breast implants and autoimmune inflammatory syndrome induced by adjuvants: description of three patients and a critical review of the literature

Silicone has been widely used in the manufacture of medical implants. It is well tolerated in most cases. However, in this paper we report the cases of three women who developed autoimmune/inflammatory syndrome induced by adjuvants (ASIA syndrome), namely with silicone breast implants. The symptoms in these cases include arthralgia, arthritis, myalgia, sleep disturbances, the appearance of autoantibodies, miscarriage, Raynaud's phenomenon, and involvement of autoimmune diseases (scleroderma and undifferentiated connective tissue diseases). In one patient, breast implants were removed, but no improvement was seen after the removal. The remaining two patients received the updated information about their condition, and they decided not to remove the implants. In conclusion, earlier reports that silicone is biologically relatively inert have recently been challenged with the description of ASIA syndrome.

Manufacturing of Medical Implants by Combination of Selective Laser Melting and Laser Ablation

The perfect fit of hip stem prostheses is supposed to have positive effects on their lifetime performance. Moreover, the ingrowth of tissue into the surface of the implant has to be assured to create a firm and load bearing contact. For the manufacturing of customized hip stem prostheses, the technology of Selective Laser Melting has shown promising results. Poor surface quality, however, makes it necessary to finish up the part by e.g., sand blasting or polishing. With the use of laser ablation for post-processing, reproducible and functionalized surface morphologies might be achievable. Hence, with the motive to produce customized hip stem prostheses, a combined process chain for both mentioned laser technologies is developed. It is examined what type of surface should be produced at which part of the process chain. The produced implants should contain the demanded final surface characteristics without any conventional post-processing. Slight advantages for the Selective Laser Melting regarding the accuracy for different geometrical structures of 400 μm depth were observed. However, an overall improvement of surface quality after the laser ablation process in terms of osseointegration could be achieved. A complete laser based production of customized hip stem implants is found to be with good prospects.

Evaluation of Surface Roughness and Cutting Forces During Precision Turning

The Ti-6Al-4V titanium alloy is commonly used in aerospace, automotive industries and for manufacturing of medical implants, due to its biocompatibility. The objective of this work is to investigate the performance of precision turning using conventional lathe on Ti6Al4V under dry working conditions. A range of parameters that involve the machining processes were recognized and a consensus was reached to finalize its values. The proposed work is to carry out machining under the selected levels of parameters to evaluate the cutting force and surface roughness generated as the consequence of the machining process. Cutting speed, feed rate, depth of cut and nose radiuses are considered as the machining parameters for experimentation. The variation in the surface roughness and the cutting force for the variation of each machining parameters are presented graphically.

Optimization of Micromilling by Adjustment of Inclination Angles

The manufacturing of medical implants and the micro die- and mould-machining are typical fields of application for five-axis micromilling. The machined materials diversify from NiTi shape memory alloys to hardened steels. First experimental results reveal a strong dependency of the machinability of the aforementioned engineering materials on cutter inclination angles. This paper presents a simulation-based approach mainly to optimize the tool inclination angles. The developed new algorithm is not only capable of detecting unfavourable tool inclinations for machining freeform surfaces, it also readjusts them. The verification of the established algorithm is accomplished by the machining a reference workpiece.

The shorter, the better

AbstractThe smaller the components, the shorter the pulse duration: particularly for manufacturing of medical implants the technological and economical advantages are obvious. Ultra short pulsed lasers are considered as only suitable tool for that kind of application. Meanwhile, additional industrial applications for femtosecond lasers arise (Fig. 1).

Predictive Modeling of the Ti6Al4V Alloy Surface Roughness

The prediction of surface roughness is important for all materials that undergo manufacturing processes. The Ti6Al4V titanium alloy is commonly used in aerospace, automotive and power generation industries but also in the manufacturing of medical implants, mainly because of its biocompatibility. Here we study the relationship of Ti6Al4V's surface roughness with critical machining parameters and conditions based on experimental input (machining parameters)-output (surface roughness) data derived during the turning operation. The experimental findings are converted into polynomial models through the Response Surface Methodology (RSM) and into a fuzzy logic system through the Adaptive Neuro-Fuzzy Inference System (ANFIS). The ability of these two methodologies to predict Ti6Al4V's surface roughness when machined is presented and compared. It is observed that the ANFIS predicts surface roughness with less error mainly when the data used for evaluation are not completely different to those used for training.

The medical device directives and their impact on the development and manufacturing of medical implants.

The introduction of a legal framework for the supply of medical implants is discussed with reference to the Active Implantable Medical Device Directive and the Medical Device Directive. The definitions of medical device and manufacturer are discussed. The application of the Directives to device/drug combinations is considered. All implants must meet certain essential requirements to ensure that they do not harm the patient, clinician or any third party. For most implants this will be indicated on the product or its packaging by CE; marking involving an independent organization called a Notified Body; the latter are appointed by the Competent Authority of the Member State. Devices are classified in proportion to the risk associated with them. The steps needed to be taken by manufacturers are outlined and the verification options discussed. The role of standards and the new approach to writing them in Europe is presented. After placing a product on the market, the manufacturer must set up a system of post-market surveillance, including a vigilance procedure, in order to monitor product performance. Individual Member States can exercise the safeguard clause when a product appears to have had the CE marking incorrectly applied.