Moola Mohan Reddy

Performance of Solder Bond on Thermal Mismatch Stresses in Electronic Packaging Assembly

Thermo-mechanical stresses have been considered one of the major concerns in electronic Packaging assembly structural failure. The interfacial stresses are often caused by the thermal mismatch stresses induced by the coefficient of thermal expansion (CTE) difference between materials, typically during the high temperature change in the bonding process. This research work examined the effect of bond layer on thermal mismatch interfacial stresses in a bi-layered assembly. The paper verified the existing thermal mismatch solder bonded bi-layered analytical model using finite element method (FEM) simulation. The parametric studies were carried out on the effect of change of bond layer properties in order to provide useful references for interfacial stress evaluation and the electronic packaging assembly design. These parameters included CTE, temperature, thickness, and stiffness (compliant and stiff bond) of the bond layer. The recent development on lead free bonding material was being reviewed and found to have enormous potential and key role to address the future electronic packaging assembly reliability.

Predictive Surface Roughness Model for End Milling of Machinable Glass Ceramic

Advanced ceramics of Machinable glass ceramic is attractive material to produce high accuracy miniaturized components for many applications in various industries such as aerospace, electronics, biomedical, automotive and environmental communications due to their wear resistance, high hardness, high compressive strength, good corrosion resistance and excellent high temperature properties. Many research works have been conducted in the last few years to investigate the performance of different machining operations when processing various advanced ceramics. Micro end-milling is one of the machining methods to meet the demand of micro parts. Selecting proper machining parameters are important to obtain good surface finish during machining of Machinable glass ceramic. Therefore, this paper describes the development of predictive model for the surface roughness of Machinable glass ceramic in terms of speed, feed rate by using micro end-milling operation.

Influence of cutting parameters on machinable glass ceramic processed by end milling

This experimental research work attempted to use End milling on Machinable Glass Ceramic (MGC) using micro grain solid carbide end mill under dry conditions. The predictive Surface Roughness model has been developed in terms of Spindle speed, Feed rate and axial depth of cut by Response Surface Methodology (RSM). The influence of each milling parameter analyzed and results showed that axial depth of cut was the most dominant variable. The adequacy of the model has been verified by ANOVA.

Surface Roughness Model when Machining Aluminum Nitride Ceramic with Two Flute Square End Micro Grain Solid Carbide End Mill

This research presents the performance of Aluminum Nitride ceramic in end milling using two flute square end micro grain solid carbide end mill under dry cutting. Surface finish is one of the important requirements in the machining process. This paper describes mathematically the effect of cutting parameters on surface roughness in end milling process. The quadratic model for the surface roughness has been developed in terms of cutting speed, feed rate, and axial depth of cut using the response surface methodology (RSM). Design of experiments approach was employed in developing the surface roughness model in relation to cutting parameters. The predicted results are in good agreement with the experimental results within the specified range of cutting conditions. Experimental results showed surface roughness increases with increase in the cutting speed, feed rate, and the axial depth of cut.

Surface Roughness Prediction in the End Milling Parameters of Aluminum Nitride Ceramic by Response Surface Methodology

The present experimental study aimed to examine the selected machining parameters on Surface roughness in the machining of alumina nitride ceramic. The influence of cutting speed and feed rate were determined in end milling by using Cubic boron nitride grinding tool. The predictive surface roughness model has been developed by response surface methodology. The response surface contours with respect to input parameters are presented with the help of Design expert software. The adequacy of the model was tested by ANOVA.

Joint Use of Geophysical and Hydrological Methods to Characterize Structures and Flow Geometry in a Complex Aquifer

Characterizing the hydrogeological functioning of complex crystalline aquifers requires a precise assessment of their structural and hydrodynamic heterogeneities. This study shows how the joint use of TDEM, ERT and MRS enables to characterize both alterites and weathered-fissured zones. Moreover, with complementary data such as water table measurements and hydraulic tests, the characterization of the fractured zone is also possible. A conceptual hydrogeological model is then proposed from a case study in India, thanks to this joint use of geophysical and hydrological data.

Sustainable energy solution for cogeneration plant in a modern rice mill using paddy husk.

As various technological and operational constraints exist in electricity distribution, many rural areas in India are deprived of power from the national electrical grid. In this situation sustainable energy solutions are the most viable and accessible sources for power production. Among the available sustainable resources, paddy husk is popular and has become a better and cheaper alternative for conventional fuels. In India alone nearly 33,000 modern rice mills have been established to process the paddy into parboiled rice. More than 40 million tones of husk is available per year from these mills. This shows the huge energy potential of the paddy husk. All existing modern rice mills are using boilers to generate steam for the parboiling process. This paper describes the thermal design concepts of a cogeneration plant using husk as a fuel to generate the steam and electric power from the steam after using it in the parboiling process.

Finite element analysis and modeling of temperature distribution in turning of titanium alloys

The titanium alloys (Ti-6Al-4V) have been widely used in aerospace, and medical applications and the demand is ever-growing due to its outstanding properties. In this paper, the finite element modeling on machinability of Ti-6Al-4V using cubic boron nitride and polycrystalline diamond tool in dry turning environment was investigated. This research was carried out to generate mathematical models at 95% confidence level for cutting force and temperature distribution regarding cutting speed, feed rate and depth of cut. The Box-Behnken design of experiment was used as Response Surface Model to generate combinations of cutting variables for modeling. Then, finite element simulation was performed using AdvantEdge®. The influence of each cutting parameters on the cutting responses was investigated using Analysis of Variance. The analysis shows that depth of cut is the most influential parameter on resultant cutting force whereas feed rate is the most influential parameter on cutting temperature. Also, the effect of the cutting-edge radius was investigated for both tools. This research would help to maximize the tool life and to improve surface finish.

The study of coated carbide ball end milling tools on inconel 718 using numerical simulation analysis to attain cutting force and temperature predictive models at the cutting zone

The unique properties of Inconel 718 make it a challenging material to machine especially in ball end milling operations due to high cutting force and temperature concentrated at the cutting zone. These essentially lead to accelerated tool wear and failure resulting in high costs and loss of production. In this research, finite element numerical simulation was performed using AdvantEdge to simulate ball end milling using an 8mm TiAlN coated carbide tool. Response Surface Methodology (RSM) is applied by using a 3 level 3 factorial Box-Behnken design of experiment with different combinations of cutting speed, feed rate, and depth of cut parameters with a selected range of parameters to simulate finishing operations. Temperature contour from finite element analysis showed that the highest temperature occurs near the depth of cut line just before the chip separates from the workpiece. Using multiple linear regression, a quadratic polynomial model is developed for maximum cutting force and a linear polynomial model peak tool temperature response respectively. Analysis of Variance (ANOVA) showed that feed rate had the most significance for cutting force followed by depth of cut. Also, cutting speed was found to have little influence. For peak tool temperature, cutting speed was the most significant cutting parameter followed by feed rate and depth of cut.

Performance of Silicon carbide whisker reinforced ceramic inserts on Inconel 718 in end milling process

An experimental investigation is planned in order to study the machinability of Inconel 718 with silicon carbide whisker reinforced ceramic inserts in end milling process. The relationship between the cutting speed, feed rate, and depth of cut against the response factors are studied to show the level of significance of each parameter. The cutting parameters are optimized by using Taguchi method. Implementing analysis of variance, the parameter which influences the surface roughness the most is determined to be the cutting speed, followed by the feed rate and depth of cut. Meanwhile, the optimal cutting condition is determined to have high cutting speed, low feed rate, and high depth of cut in the range of selected parameters.