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The criteria importance through intercriteria correlation (CRITIC) and range of value (ROV) combined methods were used to determine a single index for all multiple responses.

This paper used cold metal transfer (CMT) and pulse metal-inert gas (MIG) welding processes to study the weld-on-bead geometry of AA2099-T86 alloy. This study used Taguchi's approach to find the optimal setting of the input welding parameters. The welding current, welding speed and contact-tip-to workpiece distance were the input welding parameters for finding the output responses, i.e. weld penetration, dilution and heat input. The L9 orthogonal array of Taguchi's approach was used to find out the optimal setting of the input parameters.

The optimal input welding parameters were determined with combined output responses. The predicted optimum welding input parameters were validated through confirmation tests. Analysis of variance showed that welding speed is the most influential factor in determining the weld bead geometry of the CMT and pulse MIG welding techniques.

The heat input and weld bead geometry are compared in both welding processes. The CMT welding samples show superior defect-free weld beads than pulse MIG welding due to lesser heat input and lesser dilution.

The purpose of this paper is to investigate the process of fused filament fabrication (FFF) of a compliant gripper (CG) using thermoplastic polyurethane (TPU) material. The paper studies the applicability of different CG designs and the efficiency of some design parameters.

After reviewing a number of different papers, two designs were selected for a number of exploratory experiments. Using design of experiments (DOE) techniques to identify important design parameters. Finally, the efficiency of the parts was investigated.

The research finds that a simpler design sacrifices some effectiveness in exchange for a remarkable decrease in production cost. Decreasing infill percentage of previous designs and 3D printing them, out of TPU, experimenting with different parameters yields functional products. Moreover, the paper identified some key parameters for further optimization attempts of such prototypes.

The cost of conducting FFF experiments for TPU increases dramatically with product size, number of parameters studied and the number of experiments. Therefore, all three of these factors had to be kept at a minimum. Further confirmatory experiments encouraged.

This paper addresses an identified need to investigate applications of FFF and TPU in manufacturing functional efficient flexible mechanisms, grippers specifically. While most research focused on designing for increased performance, some research lacks discussion on design philosophy, as well as manufacturing issues. As the needs for flexible grippers vary from high-performance grippers to lower performance grippers created for specific functions/conditions, some effectiveness can be sacrificed to reduce cost, reduce complexity and improve applicability in different robotic assemblies and environments.

This study aims to investigate the effect of vibration on ceramic tools under dry cutting conditions and find the optimum cutting condition for the hardened steel machining process in a computer numerical control (CNC) lathe machine.

In this research, an integrated fuzzy TOPSIS-based Taguchi L9 optimization model has been applied for the multi-objective optimization (MOO) of the hard-turning responses. Additionally, the effect of vibration on the ceramic tool wear was investigated using Analysis of Variance (ANOVA) and Fast Fourier Transform (FFT).

The optimum cutting conditions for the multi-objective responses were obtained at 98 m/min cutting speed, 0.1 mm/rev feed rate and 0.2 mm depth of cut. According to the ANOVA of the input cutting parameters with respect to response variables, feed rate has the most significant impact (53.79%) on the control of response variables. From the vibration analysis, the feed rate, with a contribution of 34.74%, was shown to be the most significant process parameter influencing excessive vibration and consequent tool wear.

The MOO of response parameters at the optimum cutting parameter settings can significantly improve productivity in the dry turning of hardened steel and control over the input process parameters during machining.

Most studies on optimizing responses in dry hard-turning performed in CNC lathe machines are based on single-objective optimization. Additionally, the effect of vibration on the ceramic tool during MOO of hard-turning has not been studied yet.

This paper aims to carry out experimental investigations highlighting the role of melt flow index (MFI) in fused deposition modelling (FDM) process by varying the proportion of the Fe powder which is being used as a filler material. An attempt has been made to standardize MFI of Nylon6-Fe composite material to be used as hybrid FDM filament.

In this research work, it is proposed to make a suitable blend of composite material for FDM filament which can be used directly for rapid tooling applications. Three controllable parameters (namely, composition/proportion of the filler for hybrid filament, extrusion temperature and extrusion load) were studied by using Taguchi L9 orthogonal array (O.A.) MFI which is an indication of flowability has been selected as output parameter.

MFI of hybrid composite filament material has been studied, and Taguchi’s L9 O.A. was applied under both the conditions of lower the better type and larger the better type. It is observed that the contribution of the extrusion load, extrusion temperature and proportion of the filler material is almost similar, whether lower the better type situation is considered or larger the better type is considered. Further, an attempt has been made to standardize the MFI of Nylon6-Fe composite material for industrial applications, as no standard is available for composites (presently, ASTM-D-1238-95 standard is being used for plastic based materials only).

In recent past, researchers have studied and analysed the flow of the material through the nozzle of the FDM machine, but very little work has been reported on study of the flow characteristics of filament material before the composite material is fed into the machine. This research can open new avenues in the field of MFI and deals with comparison of MFI of the existing FDM feedstock material with the new composite material. The developed feedstock material is ferromagnetic in nature and can find wide variety of industrial applications.

In the current exploration, the machinability of three different nickel-based super-alloy materials (Inconel 625, Inconel 718 and Nimonic 90) was experimentally investigated by using a die-sinking electrical discharge machining (EDM). The effect of changing important input process parameters such as pulse on time (T_on), off time (T_off), peak current (Ip) and tool rotation (TR) was investigated to get optimum machining characteristics such as material removal rate, roughness, electrode wear rate and overcut.

Experimentation has been performed by using Taguchi L9 orthogonal design. An integrated route of fuzzy and grey relational analysis approach with Taguchi’s philosophy has been intended for the simultaneous optimization of machining output parameters.

The most approbatory factors for machining setting have been attained as: (T_on = 100 µs, T_off = 25 µs, Ip = 14 A, TR = 725 rpm) for machining of Inconel 625 and Inconel 718; and (T_on = 100 µs, T_off = 75 µs, Ip = 14 A, TR = 925 rpm) for machining of the Nimonic 90 material. Peak current has been observed as an overall influencing factor to achieve better machining process. Microstructural study through SEM has also been carried out to figure out the surface morphology for the EDMed Ni-based super alloys.

The proposed machining variables and methodology has never been presented for Nimonic 90 alloy on die-sinking EDM.

To find the suitable parameters for selective laser sintering (SLS) of selected ferro‐based powders. These parameters will help to create products having appreciable strength shown by the highest density and good surface property.

Design of experiment (L9 Taguchi design) has been used to obtain the parameters in the minimum possible number of experiments. For finding the range of various parameters selected such as scan speed, scan spacing and layer thickness, some preliminary experiments have been performed. In order to carry out varied characterization for a given type of experiment, a number of samples have been made.

An attempt has been made to observe the correlation between applied laser energy and the properties of the laser‐sintered parts. Taguchi design has been useful and has given the optimized parameters. It has also been found that the infiltration increases the strength of the part substantially compared with the property of end‐used sintered product.

The present set of experiments was limited by the range of supplied laser energy to the powder system, as the laser power could not be increased.

There is a need to search for alternative powders for manufacturing parts through SLS, which can alleviate the need to depend on customized powders, as these customized powders are limited to be used only with prescribed commercial SLS machines for their best performance. This drawback restricts their general use independent of any particular machine and it is, therefore, required to develop know‐how of powders and related process parameters for SLS. The present work is an effort in this direction in which laser sintering of a specially developed iron‐based powder mixture (Fe, Ni, Cu and Fe₃P) has been tested on an SLS machine.

The purpose of this study is to investigate the tribological performance of the developed self-healing Al6061 composite and to optimize the operating conditions for enhanced tribo-performance of the developed material.

A unique procedure has been adopted to convert the sand casted Al6061 into self-healing material by piercing a low melting point solder material with and without MoS₂. Taguchi-based L9 orthogonal array has been used to optimize the number of experiments and analyze the influence of operating parameters such as speed, sliding distance and load on material wear.

The results reveal that the paper shows the self-healing and self-repair is possible in metal through piercing low melting point alloy. Then, the load has a significant influence over other input parameters in predicting the wear behavior of developed material. Moreover, addition of MoS₂ does not affect the tribo-performance of the developed material. The study concludes that the developed self-healing Al6061 has huge potential to be used in mechanical industry.

The concept of self-healing in metals are very challenging task due to very slow diffusion rate of atoms at room temperature. Therefore, researchers are encouraged to explore the other new techniques to create self-healing in metals.

The self-healing materials had shown huge potential to be used in mechanical industry. The current investigation established a structural fabrication and testing procedure to understand the effects of various parameters on wear. The conclusion from the experimentation and optimization helps researchers to developed and create self-healing in metals.

The previous research works were not focused on the study of tribological property of self-healing metal composite. With the best of author’s knowledge, no one has reported tribological study, as well as optimization of parameters such as speed, load and sliding distance on wear in self-healing metals composite.

The purpose of this study is to manufacture test boards for re-enacting plant or field situations where vacuum chamber for expelling gas bubbles and autoclave equipment would not be accessible. This research focuses on the examination and enhancement of tensile strength for the nanocomposites consisting of uniaxial glass fiber mats, nanoclay (NC) and epoxy.

The parameters considered are the weight content of Cloisite 15A NC, the volume of glass fiber (V_gf) and the direction of glass fibers (θ). The composites are made by hand lay-up technique and tested according to ASTM D 638 standard. Taguchi L9 orthogonal array is used to design the experiments.

The results imply that the orientation of fibers exhibited high significance with a p-value of 0.001 for the upgrade of strength. NC percentage and the volume of fiber have a low effect as the p-values obtained were 0.375 and 0.294. Confirmation tests were performed at the optimal levels of parameters and the outcomes were in the permissible range of the anticipated values of S/N ratio and mean tensile strength. The negligible effect of nanoclay is due to the lack of infusion of resin into the d-spacing of clay layers due to the low configuration settings of mixing conditions which was confirmed by XRD studies. The negligible effect of glass fiber volume is due to the void content and lack of stress transfer between fibers uniformly due to the void content and improper mixing of nanoclay.

The limitation of this study is that a low-speed mechanical stirrer was used to mix NC in the epoxy and the mixture was not subjected to vacuum and ultrasonication for degassing and deagglomeration.

These composites can be used as substitute materials in place of metallic parts in the aerospace and automobile sector. These composites can be used in civil structures instead of steel and concrete, which have low strength-to-weight ratio and where the requirement of strength is in the range of 60 to 390 MPa.

The composites can be used in a variety of applications, for example, structural works, automotive panels and low-cost housing.

This research gives an idea about the combined contribution of NC, V_gf and “θ” to the improvement of tensile strength of the glass-epoxy composite.

This paper aims to accomplish friction stir welding (FSW) of Al–Li alloy AA8090 to determine optimal settings of the process parameters for higher tensile strength and higher micro-hardness (MH) to achieve the objective of adequate butt-joint strength.

An empirical relation is implemented to govern the utmost influence parameters, i.e. tool rotation speed (TRS), tool transverse speed (TTS) and dwell time (DT). Taguchi grey relational analysis (GRA) was applied for multi-response optimization of response parameters. The grey relational grades (GRs) have been calculated for both the responses MH and ultimate tensile strength to get optimal parametric settings. The variance test has been performed to check the adequacy of the model.

The Taguchi L9 orthogonal array design was used in establishing the relation between input parameter and output parameter (tensile and MH). TTS and DT have been predicted to be the two most important parameters that influence the extreme quality features of joints by using friction stir welding. Scanning electron microscopy fractography shows the ductile failure of the welded joints.

The experimental trials provided the followings results, maximum ultimate tensile strength (UTS) of 219 MPa and MH 107.1 HV under 1,400 rpm of TRS, 40 mm/min of TTS and 8 s of DT founded the optimum value through GRA.

Polyetheretherketone (PEEK) is used to manufacture biomedical implants because it has a high strength-to-weight ratio and high strength and is biocompatible. However, the use of fused deposition modeling to print a PEEK results in low strength and crystallinity. This study aims to use the Taguchi method to optimize the printing factors to obtain the highest tensile strength of the printed PEEK object. The annealing effect on printed PEEK object and crystallinity are also investigated.

This study determines the printing factors including the printing speed, layer thickness, printing temperature and extrusion width. Taguchi experimental design with a L9 orthogonal array is used to print the tensile specimen and carried out the tensile test to compare the tensile strength and porosity. Analysis of variance (ANOVA) is used to determine the experimental error and to determine the optimization printing parameters to obtain the highest tensile strength. A multivariate linear regression analysis is used to obtain the linear regression equation for predicting the theoretical tensile strength. An X-ray analysis is achieved to evaluate the crystalline of printed object. The effect of annealing is investigated to improve the tensile strength of printed part. An intervertebral lumber device is printed to demonstrate the feasibility of the obtained optimization parameters for practical application.

Taguchi experiment designs nine sets of parameters to print the PEEK tensile specimen. The experimental results and the ANOVA present that the order in which the factors affect the tensile strength for printed PEEK parts is the layer thickness, the extrusion width, the printing speed and the printing temperature. The optimized printing parameters are a printing speed of 5 mm/s, a layer thickness of 0.1 mm, a printing temperature of 395 °C and an extrusion strand width of 0.44 mm. The average tensile strength of printed specimen with the optimized printing parameters is 91.48 MPa, which is slightly less than the theoretical predicted value of 94.34 MPa. After annealing, the tensile strength increases to 98.85 MPa, which is comparable to that for molded PEEK and the porosity decreases to 0.3 from 3.9%. X-ray diffraction results show that all printed and annealed specimens have a high degree of crystallinity. The printed intervertebral lumber device has ultimate compressive load of 13.42 kN.

The optimized printing parameters is suitable for low-price fused deposition modeling machine because it does not involve a table at high temperature and can print the PEEK object with high tensile strength and good crystalline. Annealing parameters offer a good solution for tensile strength improvement.