Browsing by Author "Mohan, N.S."

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Delamination analysis in drilling process of glass fiber reinforced plastic (GFRP) composite materials
(2007) Mohan, N.S.; Kulkarni, S.M.; Ramachandra, A.
Machining processes are generally used to cut; drill, or contour composite laminates for building products. In fact, drilling is one of the most commonly used manufacturing processes to install fasteners for assembly of laminate composites. The material anisotropy resulting from fiber reinforcement heavily influences the machinability during machining. Machining of fiber reinforced plastic (FRP) components is often needed in spite of the fact that most FRP structures can be made to near-net shape and drilling is the most frequently employed secondary machining process for fiber reinforced materials. Therefore, the precise machining needs to perform to ensure dimensional stability and to obtain a better productivity of the component. The drilling parameters and specimen parameters evaluated were speed, feed rate, drill size and specimen thickness. A series of experiments were conducted using TRIAC VMC CNC machining center to machine the composite laminate specimens at various cutting parameters and material parameters. The measured results of delamination at the entry and exit side of the specimen were measured and analyzed using commercial statistical software MINITAB14. The experimental results indicated that the specimen thickness, feed rate and cutting speed are reckoned to be the most significant factors contributing to the delamination. A signal-to-noise ratio is employed to analyze the influence of various parameters on peel up and push down delamination factor in drilling of glass fibre reinforced plastic (GFRP) composite laminates. The main objective of this study is to determine factors and combination of factors that influence the delamination using Taguchi and response surface methodology and to achieve the optimization machining conditions that would result in minimum delamination. From the analysis it is evident that among the all significant parameters, specimen thickness and cutting speed have significant influence on peel up delamination and the specimen thickness and feed have more significant influence on push down delamination. Confirmation experiments were conducted to verify the predicted optimal parameters with the experimental results, good agreement between the predicted and experimental results obtained to be of the order of 99%. © 2007 Elsevier B.V. All rights reserved.
Influence of Drilling Parameters on Torque during Drilling of GFRP Composites Using Response Surface Methodology
(2018) Mohan, N.S.; Kulkarni, S.M.
Polymer based composites have marked their valuable presence in the area of aerospace, defense and automotive industry. Components made of composite, are assembled to main structure by fastener, which require accurate, precise high quality holes to be drilled. Drilling the hole in composite with accuracy require control over various processes parameters viz., speed, feed, drill bit size and thickens of specimen. TRIAC VMC machining center is used to drill the hole and to relate the cutting and machining parameters on the torque. MINITAB 14 software is used to analyze the collected data. As a function of cutting and specimen parameters this method could be useful for predicting torque parameters. The purpose of this work is to investigate the effect of drilling parameters to get low torque value. Results show that thickness of specimen and drill bit size are significant parameters influencing the torque and spindle speed and feed rate have least influence and overlaid plot indicates a feasible and low region of torque is observed for medium to large sized drill bits for the range of spindle speed selected. Response surface contour plots indicate the sensitivity of the drill size and specimen thickness to the torque. � Published under licence by IOP Publishing Ltd.
Influence of Drilling Parameters on Torque during Drilling of GFRP Composites Using Response Surface Methodology
(Institute of Physics Publishing helen.craven@iop.org, 2018) Mohan, N.S.; Kulkarni, S.M.
Polymer based composites have marked their valuable presence in the area of aerospace, defense and automotive industry. Components made of composite, are assembled to main structure by fastener, which require accurate, precise high quality holes to be drilled. Drilling the hole in composite with accuracy require control over various processes parameters viz., speed, feed, drill bit size and thickens of specimen. TRIAC VMC machining center is used to drill the hole and to relate the cutting and machining parameters on the torque. MINITAB 14 software is used to analyze the collected data. As a function of cutting and specimen parameters this method could be useful for predicting torque parameters. The purpose of this work is to investigate the effect of drilling parameters to get low torque value. Results show that thickness of specimen and drill bit size are significant parameters influencing the torque and spindle speed and feed rate have least influence and overlaid plot indicates a feasible and low region of torque is observed for medium to large sized drill bits for the range of spindle speed selected. Response surface contour plots indicate the sensitivity of the drill size and specimen thickness to the torque. Â© Published under licence by IOP Publishing Ltd.
Polymer-based composite materials possess superior properties such as high strength-to-weight ratio, stiffness-to-weight ratio, and good corrosive resistance and therefore, are preferred for high-performance applications such as in the aerospace, defense, and sport goods industries. Drilling is one of the indispensable methods for building products with composite panels. Drilling tests have been conducted on glass fiber-reinforced plastic composite GFRP laminates using an instrumented CNC milling center. Machining parameters such as drill size, feed rate, and cutting speed have been observed for damage-free drilling of GFRP materials. A series of drilling experiments have been conducted on glass fiber-reinforced polyester laminates and the responses experienced such as thrust force and torque as functions of feed rate and drill size have been characterized to develop a semiempirical relationship which correlated well with an established model in terms of cutting parameters. Results indicated that experimental values correlated better with the model of thrust for 6mm drill size than for 10mm and torque correlated better for lower feed ranges than for the higher feed ranges. © 2005 Sage Publications.
(Machining of fiber-reinforced thermoplastics: Influence of feed and drill size on thrust force and torque during drilling) Mohan, N.S.; Ramachandra, A.; Kulkarni, S.M.
2005
This research outlines the Taguchi optimization methodology, which is applied to optimize cutting parameters in drilling of glass fiber reinforced composite (GFRC) material. Analysis of variance (ANOVA) is used to study the effect of process parameters on machining process. This procedure eliminates the need for repeated experiments, time and conserves the material by the conventional procedure. The drilling parameters and specimen parameters evaluated are speed, feed rate, drill size and specimen thickness. A series of experiments are conducted using TRIAC VMC CNC machining center to relate the cutting parameters and material parameters on the cutting thrust and torque. The measured results were collected and analyzed with the help of the commercial software package MINITAB14. An orthogonal array, signal-to-noise ratio are employed to analyze the influence of these parameters on cutting force and torque during drilling. The method could be useful in predicting thrust and torque parameters as a function of cutting parameters and specimen parameters. The main objective is to find the important factors and combination of factors influence the machining process to achieve low cutting low cutting thrust and torque. From the analysis of the Taguchi method indicates that among the all-significant parameters, speed and drill size are more significant influence on cutting thrust than the specimen thickness and the feed rate. Study of response table indicates that the specimen thickness, and drill size are the significant parameters of torque. From the interaction among process parameters, thickness and drill size together is more dominant factor than any other combination for the torque characteristic. © 2005 Elsevier Ltd. All rights reserved.
(Influence of process parameters on cutting force and torque during drilling of glass-fiber polyester reinforced composites) Mohan, N.S.; Ramachandra, A.; Kulkarni, S.M.
2005