Search

The production of customized prostheses for the foot and ankle still relies on slow and laborious steps of the traditional plaster molding fabrication techniques. Additive manufacturing techniques where three-dimensional objects can be constructed directly based on the object’s computer-aided-design data in a layerwise manner has opened the door to new opportunities for manufacturing of novel and personalized medical devices. The purpose of the present study was to develop a new methodology for design and manufacturing of a customized silicone partial foot prosthesis via an indirect additive manufacturing process. Furthermore, the biomechanics of gait of a subject with partial foot amputation wearing the custom silicone foot prosthesis manufactured by the indirect additive manufacturing was characterized, in comparison with a matched healthy participant. This study has confirmed the possibility of producing silicone partial foot prosthesis by indirect additive manufacturing procedure. The amputated subject reported total comfort using the custom prosthesis during walking, as well as cosmetic advantages. The prosthesis restored the foot geometry and normalized many of gait characteristics. The findings presented here contribute to introduce a proper understanding of biomechanics of walking after wearing silicone partial foot prosthesis and are useful for prosthetists and rehabilitation therapists when treating patients after partial foot amputation.

Background Reconstruction of customized cranial implants with a mesh structure using computer-assisted design and additive manufacturing improves the implant design, surgical planning, defect evaluation, implant-tissue interaction and surgeon's accuracy. The objective of this study is to design, develop and fabricate cranial implant with mechanical properties closer to that of bone and drastically decreases the implant failure and to improve the esthetic outcome in cranial surgery with precision fitting for a better quality of life. A customized cranial mesh implant is designed digitally, based on the Digital Imaging and Communication in Medicine files and fabricated using state of the Art-Electron Beam Melting an Additive Manufacturing technology. The EBM produced titanium implant was evaluated based on their mechanical strength and structural characterization. Results The result shows, the produced mesh implants have a high permeability of bone ingrowth with its reduced weight and modulus of elasticity closer to that the natural bone thus reducing the stress shielding effect. Scanning electron microscope and micro-computed tomography (CT) scanning confirms, that the produced cranial implant has a highly regular pattern of the porous structure with interconnected channels without any internal defect and voids. Conclusions The study reveals that the use of mesh implants in cranial reconstruction satisfies the need of lighter implants with an adequate mechanical strength, thus restoring better functionality and esthetic outcomes for the patients.

Electron beam melting (EBM), an additive method and rotary ultrasonic machining (RUM), a subtractive technique have been in great demand owing to their innumerable benefits. These techniques can manufacture components from titanium alloys (such as Ti-6Al-4 V) for industries such as aerospace, medical, and automotive, etc. However, these techniques have their own limitations since they are not yet fully developed for many materials including Ti-6Al-4 V. For example, the RUM involves high machining time due to the extremely low MRR while EBM suffers with poor surface quality of final parts. Therefore, in this work, an attempt has been made to combine the additive (EBM) and subtractive (RUM) techniques. The two techniques have been integrated to overcome the limitations of one over the other. In fact, this research has aimed to minimize the surface roughness of EBM fabricated parts using RUM. The design of experiment (DOE) has been adopted to get the best combination of RUM parameters which produce a high surface finish for EBM parts. Moreover, the artificial neural network (ANN) model has been developed to predict the surface roughness effectively. The machining parameters such as coolant pressure, frequency, spindle speed, depth of cut, feed rate, and power supply of RUM have been investigated for better surface finish. It has been confirmed from this study that the surfaces with R a value less than 0.3 μm can be achieved using the proposed methodology.

Introduction: There are several commercially available hip implant systems. However, for some cases, custom implant designed based on patient-specific anatomy can offer the patient the best available implant solution. Currently, there is a growing trend toward personalization of medical implants involving additive manufacturing into orthopedic medical implants’ manufacturing. Methods: This article introduces a systematic design methodology of femoral stem prosthesis based on patient’s computer tomography data. Finite element analysis is used to evaluate and compare the micromotion and stress distribution of the customized femoral component and a conventional stem. Results: The proposed customized femoral stem achieved close geometrical fit and fill between femoral canal and stem surfaces. The customized stem demonstrated lower micromotion (peak: 21 μm) than conventional stem (peak: 34 μm). Stress results indicate up to 89% increase in load transfer by conventional stem than custom stem because the higher stiffness of patient-specific femoral stem proximally increases the custom stem shielding in Gruen’s zone 7. Moreover, patient-specific femoral stem transfers the load widely in metaphyseal region. Conclusion: The customized femoral stem presented satisfactory results related to primary stability, but compromising proximo-medial load transfer due to increased stem cross-sectional area increased stem stiffness.

During micromachining the accuracy of micro-feature is always a major concern. Using laser beam micro-milling (LBMM) the produced size is generally larger than the input design size. Another important drawback of LBMM is the formation of melt spatter around the feature geometry. The spatter adheres within the premises of the machined feature and influences the machining results, especially the geometry of previously machined features by adhering inside or around the feature. Determination of spatter size is very important when the objective is to produce an array of micro-features such as micro-channels. Thus, the minimum distance between two consecutive micro-features is necessary to be known in order to achieve safe geometry for which the size of spatter plays a significant role. The knowledge of spatter scattering and pre-calculated distance of dispersing spatter could certainly assist the machinist in estimating the safe distance between adjacent micro-channels. In this study, the micro-channe...

In micro-machining or micro-manufacturing, the accuracy of micro-feature size is a primary concern. It is possible to realize the exact sizes, but most of the time, undersize or oversize may achieve, especially when micro-machining is carried out by material removal processes based on thermal energies such as laser beam micro-milling (LBMM). This concern becomes more crucial if the objective is to generate an array of micro-features (e.g., micro-notches, micro-grooves, micro-channels, micro-holes, etc.) by laser beam machining. In this research, micro-channels have been fabricated in selected aerospace alloys including titanium alloy (Ti-6Al-4V), aluminum alloy (AA 2024), and nickel-based super alloy (Inconel 718) using Nd:YAG pulsed laser. Response surface methodology (RSM)-based mathematical models are developed for micro-channel sizes produced in each of the alloys in order to predict the corresponding micro-channel sizes in Ti-6Al-4V, AA 2024, and Inconel 718. Furthermore, the models are validated through various experimental confirmatory tests. The results reveal that the estimated errors between experimental micro-channel sizes and the anticipated sizes predicted from mathematical models have acceptable ranges. Finally, the optimized parametric combinations of involved laser parameters are proposed for optimum sizes of micro-channels to be machined in each of the tested material.

Underwater laser beam machining is considered as one of the alternative approaches to minimize the undesired impacts of dry laser beam machining (LBM) such as coarse machining kerf, high re-deposition of melt debris, and thermal damages. The underwater laser beam machining is equally suited for the fabrication of micro-features like 3D cavities, micro-holes, and micro-channels. In most of the literature studies, the water in dynamic mode (flowing with certain flow rate) is generally used to reduce the melt re-deposition and to improve the machining kerf and surface roughness. This study presents the use of water in static mode (still water with zero flow rate) rather dynamic mode, for the fabrication of micro-channels in nickel-based superalloy (Inconel 718). Instead of reducing the melt re-deposition, static water allowed to deposit more debris within the machining zone. This re-deposition is used to participate in micro-channel formation. After every initial passing scan, the re-deposited melt debris are piled up at the middle region of main channel that disturbs the beam focus at middle region. Due to focus disturbance, the piled up debris gets removed by partial melting of the central region and base metal remains unaffected due to partial heating. The main channel finally divided into two sub-channels. Geometrical characteristics (width, depth, and taper angle) were considered as the process responses in order to study the effects of laser power, pulse repetition rate, and laser scan speed. The results revealed that among other parameters, laser scan speed mainly influenced the geometrical characteristics of micro-channels.

Micro-channels have been fabricated in nickel-based superalloy (Inconel 718) through laser beam machining (LBM). Two machining mediums are employed: dry and wet medium. Under the dry medium, laser beam passes through air prior to strike with target surface while under wet medium, the laser beam first travels through a layer of distilled water and reaches the substrate after. For both the machining environments, effects of laser power, pulse repetition rate, and laser scan speed on machined channels’ width, depth, and taperness are investigated. A comparison of parametric effects on machined channels’ profiles has been carried out for the said machining conditions. The results reveal that LBM under distilled water is more productive than LBM under air environment. In one step, wet machining conditions allow to generate a set of two micro-channels, and dry conditions generate one micro-channel. Further, to achieve the optimum dimensions of micro-channels, the appropriate level of each of the investigated laser parameter is proposed.

Laser beam machining (LBM) has proven its applications and advantages over almost all the range of engineering materials. It offers its competences from macro-machining to micro- and nano-machining of simple-to-complex shapes. The hybrid approaches in laser ablation have demonstrated much improved results in terms of material removal rate, surface integrity, geometrical tolerances, thermal damage, metallurgical alterations, and many more. The flipside of LBM is the existence of universal problems associated with its thermal ablation mechanism. In order to alleviate or reduce the inherent problems of LBM, a massive research has been done during the past decade in order to build a relatively new route of laser-hybrid processes. This paper reviews the research work carried out so far in the area of LBM and its hybrid processes for different materials and shapes. The article also highlights the research gaps and future research directions in the context of laser and laser-hybrid ablation.

This study presents the investigation results of micro-channel fabrication in nickel-based super alloy (Inconel 718) by Nd:YAG laser beam machining. The effects of laser parameters on the machining performance characteristics over dimensional sizes are evaluated. Three number of laser parameters have been reserved as predictors to the naming of laser intensity, pulse frequency, and laser scanning speed. The channel’s top width, bottom width, depth, and taperness are considered as the process responses. Micrographs by SEM have been organized to study and measure the micro-sized dimensions of fabricated channels. The results showed that the selection of channel size is critical to achieve desired machining results. Wider-sized channels (for example 200 × 100 μm and 1000 × 500 μm) can more confidently be machined than narrower-sized channels (50 × 50 μm). The possible reasons behind the failure of narrow-sized micro-channel fabrication are identified. The appropriate combination of parameters that can yield the better results for 100 × 100 μm channel size are the laser intensity of 92.7 %, repetition rate of 30 kHz, and scan speed of 300 mm/s. At this combination, the channel geometries of wider-sized channels are more close to the designed geometries as compared to narrow-sized channels. Microstructures of the machined channels are also studied showing the recast layer with lamellar grain structure and phase transformation near the edges of micro-channels. The channel edges and their adjacent areas show variation in hardness relative to bulk material. This has been validated via micro-hardness profiles of the close vicinity of machined micro-channels.

Laser ablation is one of the competent machining processes to fabricate microfeatures in variety of engineering materials. This study has been progressed to evaluate the process capability of generating microchannels of various sizes (50 × 50 µm, 100 × 100 µm, 200 × 100 µm, and 1000 × 500 µm) in titanium alloy (Ti6Al4V) using Nd:YAG laser. Channel's top width, bottom width, depth, and taperness are examined as the four process responses against three laser based parameters to the naming of laser intensity, repetition rate, and scan speed. All the geometrical dimensions are measured through photographic snapshots of SEM of each fabricated channel. The results reveal that the selection of channel size is critical to achieve the desired machining geometries. Wider sized channels (such as 200 × 100 and 500 × 1000 µm) are experienced as more flexible to be generated than narrower sized channels (50 × 50 and 100 × 100 µm). The precise parametric combination is the key to realize more tight dimensional enormitie...

Five different sizes of micro-channels have been fabricated in three different aerospace alloys (nickel alloy, titanium alloy and aluminum alloy) through dry laser beam micro-milling (DLBMM) to study the four geometrical responses naming micro-channel’s top width (XT), bottom width (XB), depth (Z), and taperness of sidewalls. The RSM based mathematical predictive models and multi-objective optimization is performed to reach at the appropriate combinations of laser parameters for each size of micro-channel fabricated in each of the three materials. The second order mathematical models for each of the four geometrical responses have been developed using response surface methodology and the quantitative results of analysis of variances performed for every response.

The developed mathematical models and the optimized parameters are validated through confirmatory experimental tests as well as using statistical tools. The models are validated through a comparative study of actual experimental results and predicted results from the models corresponding to the geometrical characteristics (top width; XT, bottom width; XB, depth; Z, and taperness of sidewalls) associated with each of the five sizes of micro-channels (100x50 µm, 200x100 µm, 400x20 µm, 800x400 µm, and 1000x500 µm) generated in three aerospace materials (nickel alloy; NA, titanium alloy; TA, and aluminum alloy; AA). Then the mean differences between the actual results and the model predicted results were compared through paired-t-test. The paired t-test performed for every response of every micro-channel was evaluated by setting the analysis assumptions such as confidence level of 95 %, t-values and p-values of the mean differences of actual and predicted results.

Rectangular cross-sectional micro-channels of different sizes have been fabricated in selected aerospace alloys, including nickel alloy (Inconel 718), titanium alloy (Ti-6Al-4V) and aluminum alloy (AA 2024) through laser beam micro-milling (LBMM) with Nd:YAG pulsed laser. The laser beam micro-milling is performed under two ambient conditions such as dry conditions and wet conditions. The micro-milling processes corresponding to the machining conditions are termed as; (1) underwater laser beam micro-milling (UWLBMM), and (2) dry laser beam micro-milling (DLBMM). The effects of laser process parameters (i.e., lamp current intensity, pulse frequency and laser scanning speed) on micro-channel’s geometrical characteristics (e.g., top width, bottom width, depth, and taperness) have been experimentally investigated. In addition to micro-geometries, the microstructures and micro-hardness profiles of the ablated channels were also examined. In the light of the experimental results, discussions and analysis the research outcomes are classified into two categories according to the employed machining conditions (dry and wet).

Laser beam micro-milling (LBMM) on titanium alloy (TA), nickel alloy (NA) and aluminum alloy (AA) has been performed under dry atmospheric conditions. Five different sizes of micro-channels were produced in each of the said material. The micro-channel sizes include 100x50 µm, 200x100 µm, 400x200 µm, 800x400 µm, and 1000x500 µm. A full factorial response surface methodology (RSM) based face centered central composite design (FCCCD) was utilized to produce every size of micro-channel in every material. In this chapter the actual machining results, parametric effects on process performance measures, microstructures and micro-hardness profiles are discussed.

Micro-channels are extensively used in various engineering applications including micro-channel heat exchangers, micro-channel coolers, micro-channel heat pipes and micro-channel pulsating heat devices widely used in several important and diverse fields such as aerospace, automotive, cooling of gas turbine blades, cryogenic systems, bioengineering and many more. All such fields required different sized micro-channels according to the cooling requirements and installation space constraints. Variation or oversizing/undersizing to the designed channel geometries imparts significant disturbance to fluid flow. Different sized micro-channels of rectangular cross section were fabricated in nickel alloy (Inconel 718), titanium alloy (Ti-6Al-4V), and aluminium alloy (AA 2024) through Nd:YAG pulsed laser beam micro-milling (LBMM). The variations (in %) in actual geometrical characteristics from the designed geometries were calculated and observed for various sizes of micro-channels. Laser parametric influences on geometrical characteristics such as channel’s top width, bottom width, depth and degree of taperness are categorically evaluated for each size of micro-channel. Finally, the effect of micro-channel size on each geometrical variation is evaluated by making a comparison plots of each geometry, each size and each employed laser parameter. The results reveal that the effects of individual laser parameter on each micro-channel size and each geometrical characteristic are different for different sizes and response predictors (geometrical characteristics).

Micro-channels have been fabricated in nickel based superalloy (Inconel 718) through laser beam machining (LBM). Two machining mediums are employed; dry and wet medium. Under the dry medium, laser beam passes through air prior to strike with target surface while under wet medium the laser beam first travels through a layer of distilled water and reaches the substrate after. For both the machining environments, effects of laser power, pulse repetition rate and laser scan speed on machined channels’ width, depth and taperness are investigated. A comparison of parametric effects on machined channels’ profiles has been carried out for the said machining conditions. The results reveal that laser beam machining under distilled water is more productive than laser beam machining under air environment. In one step, wet machining conditions allow to generate a set of two micro-channels and dry conditions generate one micro-channel. Further, to achieve the optimum dimensions of micro-channels the appropriate level of each of the investigated laser parameter is proposed.

In this study, a T-peel joint test is used to evaluate the resistance of bonded and weld-bonded joints to a peeling load. Bonded and weld-bonded peel joints have poor strength with respect to peeling loading. In the current study, experimental methods are proposed to study the strength enhancement by introducing a single overlap support for a T-peel joint. The results indicate that the peel strength enhancement increases significantly with the introduction of a single overlap support. Also, the strength enhancement further increases with increases in the overlap support length.

In this Research, Taguchi optimization methodology is used to optimize Rotary Ultrasonic Machining (RUM) parameters for face milling of zirconia ceramic. The influence of the RUM parameters such as vibration frequency, vibration amplitude, spindle speed, feed rate, and depth of cut on cutting force and material removal rate (MRR) is studied. A three-level orthogonal array table is used to determine the signal-to-noise (S/N) ratios based on Taguchis design of experiments. Furthermore, analysis of variance (ANOVA) has been performed to study the relative significance of the different factors on cutting force and MRR of zirconia ceramic. Finally, verification tests were carried out to compare the predicted values of the outputs with their experimental values in order to confirm the effectiveness of the Taguchi Optimization.

During the last decade human factors is drawing more attention in the design, engineering, production, and maintenance of new industrial products especially in automotive industry. Ergonomic quality is becoming a critical criterion for the success of many products. Recently, virtual reality (VR) technique is widely applied during different phases of product development. The use of VR allows designer reducing the production of physical prototypes that are very expensive and requires long production time. Virtual humans are used in the automotive industry especially for ergonomic analysis of a virtual prototype of a car. In this research work, an ergonomic assessment for first Saudi Arabian Car known has been performed. CATIA V5 human builder module was used to develop the virtual humans of American male 50 and 95 percentile, which were utilized to carry out the ergonomic analysis of driver's seat. The main goal of the research is to develop a virtual environment (VE) that allow designers and engineer to evaluate the car interiors and driver's seat position using the digital mock-up instead of building the physical prototype, having a virtual validation of the project, in its early development phases. A successful ergonomics assessment has been performed on the digital model of the car in a semi-immersive virtual environment and recommendations were made for the driver's seat position based on the assessment.

Micro-channels are considered as the integral part of several engineering devices such as micro-channel heat exchangers, micro-coolers, micro-pulsating heat pipes and micro-channels used in gas turbine blades for aerospace applications. In such applications, a fluid flow is required to pass through certain micro-passages such as micro-grooves and micro-channels. The fluid flow characteristics (flow rate, turbulence, pressure drop and fluid dynamics) are mainly established based on the size and accuracy of micro-passages. Variations (oversizing and undersizing) in micro-passage’s geometry directly affect the fluid flow characteristics. In this study, the micro-channels of several sizes are fabricated in well-known aerospace nickel alloy (Inconel 718) through laser beam micro-milling. The variations in geometrical characteristics of different-sized micro-channels are studied under the influences of different parameters of Nd:YAG laser. In order to have a minimum variation in the machined geometries of each size of micro-channel, the multi-objective optimization of laser parameters has been carried out utilizing the response surface methodology approach. The objective was set to achieve the targeted top widths and depths of micro-channels with minimum degree of taperness associated with the micro-channel’s sidewalls. The optimized sets of laser parameters proposed for each size of micro-channel can be used to fabricate the micro-channels in Inconel 718 with minimum amount of geometrical variations.

Aluminum and its alloys are growingly used in various applications including micro-channel heat exchangers and heat sinks to facilitate heat transfer though micro-fluidic flows. Micro-channels with precise control over geometrical features are very important in order to design micro-fluidic flow dynamics and its characteristics. In this research, Nd:YAG laser beam micro-milling has been utilized to produce micro-channels in aluminum alloy (AA 2024) having cross-sectional size of 400 × 200 µm2. The objective was to control the material removal rate (MRR) of the process in order to get the micro-channels’ geometries (width, depth and taperness of sidewalls) close to the designed geometries. In this context, parametric effects of predominant laser parameters on the process performance have been categorically studied. Quadratic mathematical models have further been developed to estimate the MRR and each geometrical aspect of micro-channels over different levels of laser parameters. Additionally, multi-objective optimization has been performed to get an optimized set of laser parameters generating the accurate machining geometries with appropriate material removal per laser scan. Finally, the models and optimization results were validated through confirmatory experimental tests. The results reveal that the precised micro-channel geometries can be obtained through laser beam micro-milling by selecting the appropriate combination of laser parameters (lamp current intensity of 84.48 %, laser pulse frequency of 35.70 kHz and laser scanning speed of 300 mm/s) that can collectively remove a required amount of material thickness per laser scan.

Laser beam machining (LBM) has proven its applications and advantages over almost all the range of engineering materials. It offers its competences from macro machining to micro and nano-machining of simple-to-complex shapes. The flipside of LBM is the existence of universal problems associated with its thermal ablation mechanism. In order to alleviate or reduce the inherent problems of LBM, a massive research has been done during the past decade and in turn build a relatively new route of laser-hybrid processes. The hybrid approaches in laser ablation have demonstrated much improved results in terms of material removal rate, surface integrity, geometrical tolerances, thermal damage, metallurgical alterations and many more. This chapter reviews the research work carried out so far in the area of LBM and its hybrid processes for different materials and shapes. The literature assessment is mainly classified into seven categories named as: (1) Introduction, (2) Laser Beam Machining (LBM), (3) Laser Assisted Machining (LAM), (4) Laser Chemical Machining/Etching (LCM/E), (5) Laser Assisted Electrochemical Machining (LAECM) and (6) Under-Water Laser Ablation (UWLA) and (7) Micro-channel Applications and Fabrication Techniques. The last part of this chapter discusses the research gaps and future research directions in the context of laser and laser-hybrid ablation.

Taguchi optimization methodology is used to optimize Rotary Ultrasonic Machining (RUM) parameters for the milling of zirconia ceramic. The influence of the RUM parameters such as vibration frequency, vibration amplitude, spindle speed, feed rate, and depth of cut on the surface roughness is studied. A three-level orthogonal array table is used to determine the signal-to-noise (S/N) ratios based on Taguchi’s design of experiments. Furthermore, analysis of variance (ANOVA) has been performed to study the relative significance of the different factors on the surface roughness of zirconia ceramic. Finally, verification tests were carried out to compare the predicted values of the surface roughness with their experimental values in order to confirm the effectiveness of the Taguchi Optimization.

Computerized machinability data systems are essential for the selection of optimum conditions during process planning, and they form an important component in the implementation of computer integrated manufacturing (CIM) systems. Since statistical models for adhesively bonded tools are unavailable, the present paper presents a study of the development of a tool life, surface roughness and cutting force models for turning constructional steels, using adhesively bonded tools. These models are developed in terms of cutting speed, federate and depth of cut. These variables are investigated using design of experiments and utilization of response surface methodology (RMS).

This article presents the use of the rotary ultrasonic machining process for drilling holes in Ti6Al4V alloy which is regarded as a difficult-to-cut material due to its high-temperature strength and low thermal conductivity. This research presents an experimental investigation on the effect of the key rotary ultrasonic machining input parameters including ultrasonic power, spindle speed, feed rate, and the tool diameter on the main output responses including cutting force, hole cylindricity and overcut errors, and tool wear. No previous reports were found in literature to experimentally investigate the effect of the rotary ultrasonic machining parameters and the tool diameter on tool wear, surface integrity, and the accuracy of the drilled holes in Ti6Al4V alloy. The results showed that the rotary ultrasonic machining input parameters within the current ranges can significantly affect the quality of the drilled holes. Through proper selection of input parameters, holes could be drilled in Ti6Al4V alloy with smoothed surface morphology, low tool wear (0.7 mg) and very low cylindricity (2 µm) and overcut (120 µm) errors. Moreover, it was found that the selected level of any input parameter has the ability to significantly affect the influence of the other input parameters on the output responses.

A wide range of materials may be used in manufacturing tibia trays of artificial knee replacements. The Young's modulus of the prosthesis is a critical design variable, since it largely determines how the load is transferred, via the cement to the bone. The current investigation deals with the effect of Young's modulus of the prosthesis and cement and on the stresses developed in the constituents and surrounding bones of artificial knee. Two practical tibia tray materials of diversified Young's modulus were considered in the present work. These showed that increasing the Young's modulus of the prosthesis resulted in weakening the cement layer, while its effect on other constituents is insignificant. A 50% increase in cement Young's modulus resulted in strengthening both the polyethylene and cement layers.

Virtual reality (VR) is a technology that has existed since the 1960s, but due to its high equipment cost, its use was limited. During the last decade, advancements in computers and reduction of technology costs made VR accessible and its applications widespread in various fields, including manufacturing. In this paper, a virtual environment for a robotic cell is developed, so that the layout design is validated and implementation planning is conducted to set up the real robotic cell. We show how the developed semi-immersive environment provides users with a sense of presence in the digital environment, and how it enables them to work with 1∶1 scale digital objects as in the real world. The application of the developed virtual environment is further discussed for teaching and training purposes.

In orthopedic surgery, a semi constraint hinged prosthesis is inserted between the metacarpal and the first phalanx of the index finger. The purpose of the Implants development to allow maximum joint flexibility, and reduce joint pain effectively. In this paper; first the review of all the related areas is carried and after that with help of an implant study on loading conditions, deformation and stresses is analyzed. The research contribution is the development of a new implant with brief literature review and aligning the implant development criteria with different prospective of literature. The data from Computer Tomography is imported into MIMICS software and then segmentation is performed. The 3-D model for the finger joints is developed using Solid works software. Fixation of the implant to the gap location was performed using MIMICS. The analysis of normal finger with respect to the implanted is done through ANSYS software. The materials were assumed to be homogeneous, isotropic and linear elastic. Additive manufacturing technology is used to finally manufacture the implant.

The weld-bonding process is essentially the spot-resistance welding of parts that subsequently have their overlapping areas adhesive-bonded. Two distinct techniques are normally used for manufacturing weld-bonded structures namely; weld through and flow-in. The present work is concerned with the thermal stresses developed in weld-bonded joints, throughout their manufacturing stage. The most influential factors that have been studied and evaluated are the weld bonding technique, the type of adhesive material, the electrode pressure and the bond line thickness.

The aim of the present work is to study the most influential parameters governing the strength of weld-bonded joints. The thickness and elastic modulus of adhesive, the stress concentration factor and the adherent materials, were all considered and their effectiveness evaluated. The present work demonstrated that for rationale design of weld-bonded joints, adhesives with the less Young's modulus available should be coupled with maximum permissible gap thickness.

The aim of the present work is to analyse spot-welded dissimilar material joints. The finite element technique was used for the analysis of the present work. The present work shows that the stresses are more concentrated towards the member that has the lowest melting point in the joint. However, the introduction of an adhesive layer in conjunction with the spot weld nugget resulted in eliminating the stress concentration and strengthening dissimilar material joints.

The present work aimed at investigating the effect of thickness dissimilarity on the peel and shear strength of spot-welded dissimilar thickness joints. Finite element analysis was used throughout the present work. The present work showed that thickness dissimilarity magnifies the stress concentration located at the boundaries of the weld nugget. The level of stress concentration developed in the thinner part of the joint is higher than that developed in the thicker part. However, the introduction of an adhesive layer in conjunction with the spot weld nugget resulted in improving the peel and shear strength of spot-welded dissimilar thickness joints, through reducing the associated level of stress concentration.

The present work aimed at predicting the strength of weld-bonded joints having square or spew fillet adhesive layer. For comparison purposes, adhesive bonded and resistance spot-welded joints were also included in this study. The present work demonstrated that, the major principal stress predicted in joints having spew fillet adhesive layer is lower than that predicted in joints having adhesive layer with square edges. Consequently, it is advised to use adhesive layer having spew fillet to strengthen weld-bonded joints.

The aim of the present work is directed towards the manufacturing and characteristics of weld-bonded commercial aluminum sheets. Dynamic response (natural frequency and damping), nugget size, and tensile shear strength were tested and reported. The present work demonstrates a tremendous improvement in tensile shear strength associated with higher damping capacity for weld-bonded joints. However, the natural frequency seems to be independent on shear strength as well as joining technique (spot welding or weld bonding).

It is well established that weld-bonded joints enhance the fatigue as well as the corrosion resistance of resistance welded joints. In the present work, both techniques of weld-bonding, namely, weld-through and flow-in, have been evaluated. Metallic fillers at optimum percentages were also tried in order to enhance the electrical conductivity of the adhesive material. The present work demonstrated that the flow-in technique is far better when compared with the weld-through technique, both from economical as well as technological points of view.

Different techniques are normally used for assembling insert-holders of metal cutting tools. For instance, mechanical clamping, brazing, and adhesive bonding are common techniques for assembling metal cutting tools insert-holders. The present work addresses the impact of the assembly technique on the dimensional accuracy and geometrical tolerances of machined workpieces. Extensive cutting tests conducted on mild steel specimens using different insert holder assembly techniques revealed that bonded assembly ranked ahead in preserving dimensional accuracy and geometrical tolerances, when compared with mechanical clamped and brazed assemblies.

Soldering is associated mainly with the electronics and military industries, which always prefer to preserve their ‘know-how’ on this subject. Thus, the main objective of the present work is to establish a knowledge-base for electronics soldering. This includes: materials for soldering, soldering processes, cleaning for soldering, and trouble shooting for soldering.

The objective of the present work, is to investigate the feasibility of machining hard materials with bonded tools. In the present work, a nickel-based superalloy namely; supermet 718 has been machined with bonded as well as mechanically clamped tools. The present work demonstrates a favorable effect for bonded tools on surface roughness, when compared with mechanically clamped tools. However, the tool wear seems to be unaffected by the technique of cutting tool assembly.

The objective of the present work is to assess the effect of the tool material and the cutting parameters on surface roughness of supermet 718 nickel-base superalloy, under dry cutting conditions and a constant nose radius (0.5 mm). The tool materials used were ceramic (Sandvik CC680)and CBN (Sandvik CB5O) inserts. These variables were investigated using a 2 k factorial design. The present work demonstrates a favorable effect for ceramic inserts on surface roughness, when compared with CBN inserts. The work also showed that the feed-rate has the dominant effect on surface roughness amongst the parameters studied, irrespective of the tool material used.

In the present work, experiments planned on the basis of statistical experimental design were carried out to study the influence of welding parameters (welding current, welding time, electrode force and sheet thickness) on the microhardness and strength of spot joints. Tensile shear strength, microhardness and nugget area of spot-welded commercial aluminium sheets (B.S. 1050) were measured, reported and correlated.

Experimental results of a study on geometric accuracies of NC- and manually-drilled holes are presented. The effects of the cutting speed, feed rate and drill diameter on the dimensional accuracy, surface quality and geometrical tolerances of NC- and manually-drilled holes are considered, compared, and reported.

The objective of the present work, is to assess the effect of tool material and cutting parameters on surface roughness of the supermet 718 Nickel-base superalloy, under dry cutting conditions and ...

The intense global competition in the manufacturing of high quality products has led production engineers to consider tolerances as the key parameter in the achieving of their goal. Thus, all features on component parts should have a toleranced size and geometrical shape, and nothing should be left to judgement in the workshop or in the inspection department. In the present work, the process of specifying general tolerances for dimensions and features left without individual tolerance indications has been automated. The work is designed to suit any system of units; that used here is the ISO standard. A test sample based on ISO is given also.

This paper presents a study of the development of surface roughness models for turning supermet 718 nickel super alloy (300 BHN), using different tool materials namely; CBN (SANDVIK CB50), Carbide (SANDVIK HIP k10), and ceramic (SANDVIK CC680) under dry cutting conditions and a constant nose radius. The models are developed in terms of cutting speed, feed rate, and depth of cut. These variables were investigated using design of experiments and utilization of the response surface methodology (RSM). A separate surface roughness model corresponding to each tool material is established, tested and reported.

In the present work, spot welding and weldbonding have been adopted for manufacturing bimaterials. Spot welding parameters namely, welding current, electrode force and welding cycles have been optimized and reported for manufacturing bimaterial (brass-steel) damping sheets. Tensile strength, fatigue strength, microhardness measurements and microstructure examination have been performed and are reported. The present work demonstrates tremendous improvement in fatigue strength associated with weldbonding, when compared to spot welded bimaterials.

In the present work, gas metal arc welding (GMAW) and adhesive bonding have been considered as mild steel notch filling techniques. Static as well as dynamic characteristics of filled and unfilled specimens, at different notch angles are assessed and reported. The present work showed that adhesive bonding is a far superior notch filling technique, when compared with gas metal arc welding due to the absence of distortions, minimum or no metallurgical damage, added to the good joint sealing and better appearance. The present work suggests that metals be cut before repair to a notch angle of 60°, since maximum ultimate strength (546 MPa) was obtained at a 60° notch angle.