Hari Singh

Optimization of machining techniques — A retrospective and literature review

In this paper an attempt is made to review the literature on optimizing machining parameters in turning processes. Various conventional techniques employed for machining optimization include geometric programming, geometric plus linear programming, goal programming, sequential unconstrained minimization technique, dynamic programming etc. The latest techniques for optimization include fuzzy logic, scatter search technique, genetic algorithm, Taguchi technique and response surface methodology.

Taguchi-fuzzy multi output optimization (MOO) in high speed CNC turning of AISI P-20 tool steel

Research highlights? The multi output high speed CNC turning of AISI P-20 tool steel is optimized using fuzzified Taguchi approach. ? In multi-response problem, all 4 responses tool life, power consumption, cutting force and surface roughness were simultaneously considered. ? It is concluded cutting speed (160m/min), nose radius (0.8mm), feed (0.1mm/rev) & depth of cut (0.2mm) yield ptimal result. ? Most significantly- cryogenic machining environment is favourable in increasing tool life and reducing surface roughness, cutting force and power consumption compared to wet coolant. This paper presents the application of Taguchi method with logical fuzzy reasoning for multiple output optimization of high speed CNC turning of AISI P-20 tool steel using TiN coated tungsten carbide coatings. The machining parameters (cutting speed, feed rate, depth of cut, nose radius and cutting environment) are optimized with considerations of the multiple performance measures (surface roughness, tool life, cutting force and power consumption). Taguchis concepts of orthogonal arrays, signal to noise (S/N) ratio, ANOVA have been fuzzified to optimize the high speed CNC turning process parameters through a single comprehensive output measure (COM). The result analysis shows that cutting speed of 160m/min, nose radius of 0.8mm, feed of 0.1mm/rev, depth of cut of 0.2mm and the cryogenic environment are the most favorable cutting parameters for high speed CNC turning of AISI P-20 tool steel.

Optimizing feed force for turned parts through the Taguchi technique

The objective of the paper is to obtain an optimal setting of turning process parameters (cutting speed, feed rate and depth of cut) resulting in an optimal value of the feed force when machining EN24 steel with TiC-coated tungsten-carbide inserts. The effects of the selected turning process parameters on feed force and the subsequent optimal settings of the parameters have been accomplished using Taguchi’s parameter design approach. The results indicate that the selected process parameters significantly affect the selected machining characteristics. The results are confirmed by further experiments.

Optimizing multi‐machining characteristics through Taguchi's approach and utility concept

Purpose – Taguchis technique is best suited to optimize a single performance characteristic yielding an optimal setting of process parameters. A single setting of process parameters may be optimal for one quality characteristics but the same setting may yield detrimental results for other quality features. Thus the purpose of this paper is to describe simultaneous optimization of multi‐characteristics.Design/methodology/approach – The multi‐machining characteristics have been optimized simultaneously using Taguchis parameter design approach and the utility concept. The paper used a single performance index, utility value, as a combined response indicator of several responses.Findings – A simplified model based on Taguchis approach and utility concept is used to determine the optimal settings of the process parameters for a multi‐characteristic product. The model is used to predict optimal settings of turning process parameters to yield the optimum quality characteristics of En24 steel turned parts usin...

Parametric Optimization of Cryogenic-Treated D-3 for Cutting Rate in Wire Electrical Discharge Machining

Cryogenic treatment (Cryo) is a supplementary process to improve the properties of metals like high carbon high chromium alloy tool steels (D-3) which are increasingly used in manufacturing high-performance cutting tools (dies and punches), blanking and punching tools, extrusion tools, parts of aerospace and automotive industries, etc. The purpose of this study is to investigate the effect of parameters like pulse width, time between two pulses, maximum feed rate, servo reference mean voltage, short pulse time, and wire mechanical tension, on cutting rate (cr) of cryogenic-treated D-3 in wire electrical discharge machining. An L27 orthogonal array has been used to conduct experiments and statistically evaluate the experimental data by analysis of variance (ANOVA). It is seen that cr decreases with increase in pulse width, time between two pulses, and servo reference mean voltage. cr first decreases and then increases with increase in wire mechanical tension. The confirmation experiments have also been conducted to validate the results obtained by Taguchi technique.

Performance analysis for D-3 material using response surface methodology on WEDM

The present paper identifies process parameters that affect metal removal rate and surface roughness in machining of cryogenic treated D-3 material on wire-cut electric discharge machine tool. Central composite design is used to plan and conduct the experiments. The regression is employed to develop empirical relationships between different process parameters and output responses, and subsequently to analyse and yield the optimal values of process parameters. As the effect of process parameters on metal removal rate and surface roughness is contrary, the problem is formulated as a multi objective optimisation problem and solved using weight method. Effort is made to find the machine settings to obtain maximum metal removal rate and minimum surface roughness. Confirmation experiments are also carried out which reflect that the developed mathematical models are appropriate for the effective machining of D-3 material. The optimal combination of WEDM process parameters obtained from the study satisfies the real requirement of quality machining of D-3 material in practice. In this research paper, cryogenic treatment of work piece is carried out before machining for improving the wear resistance of the material which is necessary for die manufacturing.

Multicharacteristic optimisation of CNC turned parts using principal component analysis

This paper optimises the multiple characteristics (tool life, cutting force, surface roughness and power consumption) in CNC turning of AISI P-20 tool steel using Principal Component Analysis (PCA). Five controllable factors of the turning process were studied at three levels each viz cutting speed, feed, depth of cut, nose radius and cutting environment. L27 Orthogonal array was used for conducting the experiments. The single response optimisation was conducted by Taguchi method. PCA was employed to correspond to multi response cases. The optimum combination of process factors based on first principal component was determined which was subsequently studied by extracting more then one principal component and integrating into comprehensive index. Finally, the Analysis of Variance (ANOVA) was used to find out the most influential CNC turned parameter for multiple response problems.

Comparison of optimized settings for cryogenic-treated and normal D-3 steel on WEDM using grey relational theory

Cryo process is the process of treating work-pieces to cryogenic temperatures (i.e. −184 ℃) to remove residual stresses and improve wear resistance of steels. It improves the surface properties of the materials. Aerospace and tool industries use this treatment to enhance the dimensional stability and wear resistance. In this research paper, a comparison has been presented for normal and cryogenic-treated high carbon high chromium cold alloy tool (D-3) steel. The response variables namely cutting rate, metal removal rate, and surface roughness are considered for experimentations and six input process parameters like pulse width, time between two pulses, servo reference mean voltage, short pulse time, maximum feed rate, and wire mechanical tension were used for optimization on wire electric discharge machine. Grey relational analysis has been applied to calculate the grey relational coefficients and grey relational grade. ANOVA is also performed to know the significant factors for multi-response optimization.

Modelling of machining parameters and cooling conditions in hard turning of AISI p-20 tool steel using response surface methodology and desirability graphs

This paper presents mathematical models for correlating the CNC machining parameters such as cutting speed, feed rate, depth of cut, nose radius, with the cutting force acting on the cutting tool during turning of prehardened P-20 tool steel. The face centred central composite design module of Response Surface Methodology (RSM) has been used for conducting the experiments. Machining is done under three different environmental conditions - dry, wet (conventional coolant ILO cut 154 Indian Oil) and cryogenic (liquid nitrogen). The significance of the mathematical models developed was ascertained using desirability graph and confirmation experiments. The results obtained show that the mathematical models are useful not only for predicting optimal process parameters for achieving the desired quality but also for achieving the process optimisation. The cutting force contours have been generated from the model equations. Desirability graphs are also drawn giving minimum cutting force a value of one.

MEDISCRIPT- MOBILE CLOUD COLLABRATIVE SPEECH RECOGNITION FRAMEWORK

This work presents a CAD paradigm to produce traditional zillij style of geometrical patterns using ubiquitous polygonal technique. This method makes use of a grid generated from diagonals of n-sided regular polygon. The grids are in the form of a mesh of having large number of irregular polygons. The vertex of any irregular polygon in the grid is viewed as the point of intersection of two diagonals. These irregular polygons, when located in radial symmetry, generate a zillij style of pattern. The design possibilities increase by increasing the diagonals elements and endless variations of patterns on an isometric grid can be created. These geometrical patterns are ideally suited to computer-controlled manufacturing, so can be executed on a flat wooden surface to produce carvings.Speech recognition is a vital part in medical transciription. The existing speech recognition systems, that run as standalone desktop applications, fall short in many cases due to low accuracy rates and high processing time. The bottleneck in these systems, is the lack of computation power (in terms of processing power and memory) made accessible to them. This paper proposes a mobile-cloud collaborative approach for the automation of speech to text conversion. The model proposed leverages the power of cloud computing and the ubiquitous nature of mobile computing. Computing resthisces can be scaled up/down in the cloud (Elastic Computing) depending on the usage of the system. This kind of speech recognition framework has many real time applications such as IVR systems, Medical Transcription systems, Railway Enquiries, Jthisnalism, Interactive User Interfaces, etc. A generic framework is advantageous, because the speech models in the Automatic Speech Recognizer (ASR) could be trained according to the specific domain required, allowing wide usability. The proposed speech framework is used for medical transcription process. Medical transcription process involves a medical transcriptionist who listens to the recorded speech of a doctor and manually types a transcript file. This process is automated by using the proposed speech framework. With this system, the work of the medical transcriptionist is reduced to error checking in the auto generated transcript file. The entire model is developed for a mobile cloud environment considering the characteristics of cloud delivery models.