Arshad Noor Siddiquee

Multi-response optimization of wire electrical discharge machining process parameters for Al7075/Al2O3/SiC hybrid composite using Taguchi-based grey relational analysis

The effect of various wire electrical discharge machining process parameters such as pulse on time, pulse off time, pulse current and the wire drum speed on machined surface quality characteristics such as surface roughness and kerf width has been discussed. The experiments were carried out with L27 orthogonal array on hybrid metal matrix composite prepared by inert gas–assisted electromagnetic stir casting process using particulates 7.5% Al2O3 and 7.5% SiC each in Al7075 alloy. Taguchi-based grey relational analysis, a multi-response optimization technique, was used to find the optimal process parameter setting for the best quality machined characteristics. Results of analysis of variance showed that the order of significance was pulse on time, pulse current, pulse off time and the wire drum speed contributing 50.02%, 39.50%, 4.58% and 2.75%, respectively, while machining the hybrid composite. Confirmation test was carried out at selected optimal parameter setting, which showed improvement in grey relational grade, thus confirming the robustness of grey relational analysis.

Investigations on the effect of wire EDM process parameters on surface integrity of HSLA: a multi-performance characteristics optimization

Surface roughness (Ra) and micro-hardness (μh) are two important constituents of the surface integrity (SI) of the machined component. In Wire Electric Discharge Machining (WEDM), the machining factors that affect SI are generally the pulse on-time, pulse off-time, current, etc. This paper presents a study that investigates the effect of the WEDM parameters on the surface roughness average and the micro-hardness of the High Strength Low Alloy steel (ASTM A572-grade 50). Nine experimental runs based on an orthogonal array of Taguchi method are performed and grey relational analysis (GRA) method is subsequently applied to determine an optimal WEDM parameter setting. The SI parameters i.e. surface roughness and micro-hardness are selected as the quality targets. An optimal parameter combination of the WEDM process is obtained using GRA. By analyzing the grey relational grade matrix, the degree of influence for each controllable process factor onto individual quality targets can be found. The pulse off-time is found to be the most influential factor for both the surface roughness and the micro-hardness. Further, the results of the analysis of variance reveals that the pulse off-time is the most significantly controlled factor for affecting the SI in the WEDM, according to the weighted sum grade of the surface roughness and the micro-hardness.

Issues and strategies in composite fabrication via friction stir processing: A review

ABSTRACT Friction stir processing (FSP) is an expeditiously emerging novel technique involving exterior layer modification, which enables one to successfully fabricate surface composites (SCs) as well as bulk composites of the metal matrix. SCs constitute an exclusive class of composites which exhibit improved surface properties while retaining the bulk properties unaltered. During initiative years, FSP was employed in development of SCs of light metal alloys like aluminum. But, nowadays, it has gained a shining role in the field of SC fabrication of various nonferrous alloys like aluminum, magnesium, copper, and even ferrous metals like steel etc. This article reviews the current trends, various issues, and strategies used to enhance the efficiency of the fabrication process of SCs. Factors involved in the process of SC fabrication are discussed and classified with a new approach. Also, variation of microstructural and mechanical characteristics with these factors is reviewed. In addition to a brief presentation on the interaction between various inputs and their effects on properties, a summary of literature on SC fabrication for different metals is tabulated with prominent results. Subsequently, shortfalls and future perspectives of FSP on SC fabrication domain are discussed.

A review of turning of hard steels used in bearing and automotive applications

Hard turning is a recent technology that involves machining of hard steels using modern machine tools. Hard machining presents challenges in terms of selection of tool insert with improved tool life and high-precision machining. Turning of hardened steels using single-point cutting tool has got considerable interest among manufacturers of ball bearings, automotive, gear, and die industry. Hard turning in the automotive industry and bearing applications typically has a number of potential benefits over traditional form grinding including lower equipment costs, shorter setup time, and fewer process steps which in turn provides high flexibility and ability to cut complex geometries. Moreover, the hard turning process is usually carried out without coolant/lubricant and thus, the problem of storage, handling, and disposal of cutting fluid is eliminated, and at the same time, it probably favors the health of operators. This paper presents an overview of the past research hard turning using hard turning tools such as PCBN, cubic boron nitride, Ceramics, Carbide, etc. Major hard turning cutting materials and effect of hard turning process parameters on cutting forces, heat generation during cutting, surface finish and surface integrity, and tool wear have been discussed in light of the findings of the past research.

Review on effect of flux composition on its behavior and bead geometry in submerged arc welding (SAW)

Performance of a welding flux is decided by the physical and chemical properties of its constituents. The flux selected should show a good welding behavior and the required weld bead geometry. The mechanical properties of a joint are not only decided by its composition but these also depends on bead geometry, dimensions and physico-chemical properties of fluxes. These properties include surface tension, viscosity, heat capacity, thermal coefficients of expansion, grain size etc. These properties of fluxes primarily affect the flux behavior, bead shape and size, welding speed, current carrying capacity, protection of molten metal, arc stability, slag detachability, capillarity, surface tension and viscosity. Various constituents of a welding flux have major influence on the performance of welding processes and weld bead dimensions. We need to understand the physical properties and behavior of fluxes during submerged arc welding. The influence of specific flux additions on arc stability, viscosity, capillarity, slag detachability and weld bead shape need to be better characterized. It can be inferred that we cannot obtain the weld of desired geometry and composition until we consider the physico-chemical characteristics of flux like slag viscosity, surface tension, arc stability and slag detachability, capillarity and weld penetration. So, while designing the flux or during selection of welding process parameters the above characteristics should be carefully controlled or selected. n n xa0 n n Key words:xa0Submerged arc welding, bead width, reinforcement, weld penetration, bead morphology.

Optimization of wire electrical discharge machining process parameters on material removal rate for Al7075/SiC/Al2O3 hybrid composite

This article investigated the effect of wire electrical discharge machining process parameters such as pulse on time, pulse off time, pulse current and the wire drum speed on the material removal rate, while machining newly developed hybrid metal matrix composite (Al7075/7.5%SiC/7.5%Al2O3). The hybrid composite was prepared by inert gas–assisted electromagnetic stir casting process. Taguchi method was used for parameter optimization and the level of importance was determined using analysis of variance. The results showed that pulse on time, pulse off time and pulse current were significant parameters. The pulse on time was the most significant parameter that contributed maximum (46.04%) to the material removal rate followed by pulse current (34.72%), pulse off time (10.23%) and interaction, pulse on time × pulse off time (5.46%). The wire drum speed had insignificant effect on the material removal rate. In confirmation test, the average experimental value of material removal rate was within the predicted optimum class interval.

An investigation on effects of wire electrical discharge machining parameters on surface roughness of newly developed hybrid metal matrix composite

This article investigated the effect of wire electrical discharge machining process parameters such as pulse on time, pulse off time, pulse current and the wire drum speed on the surface roughness of machined hybrid metal matrix composite. The hybrid composite was prepared by inert gas–assisted electromagnetic stir casting process using 15 wt% Al2O3/SiC particulates (7.5% each) in metal matrix Al-7075 alloy. Taguchi method was used for parameter optimization, and the level of importance was determined using analysis of variance. The MINITAB15 software was used in the analysis. The results show that pulse on time, pulse current and pulse off time were significant parameters, whereas the wire drum speed had insignificant effect. In confirmation test, the average experimental value of surface roughness was within an error of 3.46% of the predicted value at the optimum level of process parameters.

Investigation of surface integrity during wet turning of hard alloy steel

This paper presents a study that investigates the effect of the CNC hard turning parameters on the surface integrity (SI), defined in terms of surface roughness average (Ra) and the micro-hardness MH, of hard steel (AISI 52100) under wet cutting conditions. Nine experimental runs based on an orthogonal array of Taguchi method are performed and grey relational analysis method is subsequently applied to determine an optimal cutting parameter setting. The SI parameters, i.e., surface roughness average and micro-hardness are selected as the quality targets. An optimal parameter combination of the turning operation is obtained using grey relational analysis. By analysing the grey relational grade matrix, the degree of influence for each controllable process factor onto individual quality targets can be found. The feed rate is identified to have the most influence on the roughness average and also on the micro-hardness. Further, the analysis of variance (ANOVA) is also applied to identify the most significant factor; the feed rate is the most significant controlled factors for affecting the SI in the turning operations according to the weighted sum grade of the surface roughness average and micro-hardness.

Review on underwater friction stir welding: A variant of friction stir welding with great potential of improving joint properties

Abstract Friction stir welding (FSW) is a solid-state welding process which is capable of joining materials which are relatively difficult to be welded by fusion welding process. Further, this process is highly energy-efficient and environmental-friendly as compared to the fusion welding. Despite several advantages of FSW over fusion welding, the thermal cycles involved in FSW cause softening in joints generally in heat-treatable aluminum alloys (AAs) due to the dissolution or coarsening of the strengthening precipitates leading to decrease in mechanical properties. Underwater friction stir welding (UFSW) can be a process of choice to overcome these limitations. This process is suitable for alloys that are sensitive to heating during the welding and is widely used for heat-treatable AAs. The purpose of this article is to provide comprehensive literature review on current status and development of UFSW and its importance in comparison to FSW with an aim to discuss and summarize different aspects of UFSW. Specific attention is given to basic principle including material flow, temperature generation, process parameters, microstructure and mechanical properties. From the review, it is concluded that UFSW is an improved method compared with FSW for improving joint strength. Academicians, researchers and practitioners would be benefitted from this article as it compiles significantly important knowledge pertaining to UFSW.

Distribution of reinforcement particles in surface composite fabrication via friction stir processing: Suitable strategy

ABSTRACT Fabrication of metal matrix surface composites (SCs) is an emerging trend of friction stir processing applications. Key factors affecting the properties of SCs are process parameters, tool geometry, tool dimensions and reinforcement strategies. In this research, effects of different reinforcement strategies and varying tool offset positions on dispersion of reinforcement particles in the base matrix are investigated. The experiments were performed in two phases using AA6063 as base metal at constant process parameters of 1120u2009rpm rotational speed, 40u2009mm/min traverse speed and 2.5° tilt angle. In the first phase, effect of six different reinforcement strategies on the reinforcement particles distribution and defect formation was studied. It was found that groove method with tool offset in retreating side (RS) exhibited better homogeneity in reinforcement distribution out of the six reinforcement strategies considered. In the second phase, effect of variation of tool offset in RS was investigated. Results from second phase of experimentation reflected that the best dispersion of reinforcement powder with larger stir zone area was found with 1.5u2009mm tool offset which is numerically half of the tool pin radius. The results were supported by macro and microstructural images obtained from the optical microscope and scanning electron microscope.