M.S.J. Hashmi

COMPUTER-AIDED ANALYSIS OF A SURFACE-ROUGHNESS MODEL FOR END MILLING

Abstract The factors which affect the surface finish produced in the end milling process are generally the cutting speed, the feed, the depth of cut, etc. This paper describes a study of the development of a surface-roughness model for the end milling of 190 BHN steel. The model for the mathematical prediction of the surface roughness has been developed in terms of cutting speed, feed and axial depth of cut. The effect of these cutting parameters on the surface roughness has been investigated using response surface methodology. Response surface contours were constructed by computer and used for determining the optimum cutting conditions for a required surface roughness.

Optimization of surface finish in end milling Inconel 718

Abstract This paper presents an approach to optimize the surface finish in end milling Inconel 718 using uncoated carbide inserts under dry conditions. In view of this, the mathematical models for surface roughness have been developed in terms of speed and feed by response surface methodology. Response surface contours were constructed in speed feed planes by computer. From these contours it was possible to select a combination of cutting speed and feed that reduces machining time without increasing the surface roughness. These were obtained by superimposing the constant lines of metal removal rates on the surface roughness contours.

Prediction of tool life in end milling by response surface methodology

Abstract This paper presents a study of the development of mathematical models for tool life in end milling steel (190 BHN) using high-speed steel slot drills under dry conditions. The predictive models for tool life have been developed in terms of primary machining variables such as cutting speed, feed and axial depth of cut by response surface methodology. A first-order equation covering a narrow range of the variables and a second-order equation covering a wide range of the variables are presented. Response surface contours were constructed in speed-feed planes and used for determining the optimum cutting conditions for a required to life. The adequacy of the predictive models was tested by analysis of variance and found to be adequate.

AN ANN AND TAGUCHI ALGORITHMS INTEGRATED APPROACH TO THE OPTIMIZATION OF CO2 LASER WELDING

Abstract Nowadays several numerical methods are widely used for either modelling or optimizing the performance of the manufacturing technologies. That has been advanced due to the large diffusion of the personal computer and the numerical algorithms. The knowledge of those methods and the ability in integrating their functions can make both the manufacturing engineer and the researcher ace their duties. In this paper, two of those methods have been employed, the backpropagation artificial neural network and the Taguchi approach to the design of the experiment. They were applied to find out the optimum levels of the welding speed, the laser power and the focal position for CO2 keyhole laser welding of medium carbon steel butt weld. The optimal solution is valid in the ranges of the welding parameters that were used for training the neural networks. Extrapolation over those limits would restrict the applicability of the found solution. The proposed approach would be extendable to other keyhole laser welding processes for different materials and joint geometries.

Testing of composite materials at high rates of strain: advances and challenges

Abstract This review paper is devoted to discussing the development and the present state of some key aspects of the mechanical behaviour of composite materials under impact loading. The experimental techniques employed for determining the behaviour of composite materials at high strain rate in tensile, compressive and shear loading are presented and discussed. The discussion includes their fundamental advantages and limitations. Directions for future research are also indicated.

Plastics and their machining: A review

Abstract Many different families of plastics are used in industry. The demand for the machining of plastics has recently increased. In most cases, traditional metal machining techniques and tools are being used in the machining of plastics. The present paper reviews the conventional mechanical machining of plastics. The cutting phenomena as indicated by the types of chips formed under various cutting conditions, and the cutting forces for the single-edge cutting of two broad types of plastics are discussed. When drilling plastics, the type of chip produced, the torque, and the thrust are considered. A general idea about the milling of plastics is shown. The possibility of grinding thermosets and thermoplastics using an open grinding wheel is discussed with reference to bond type, grit type, grit size and porosity.

Estimation of machine parameters for hydraulic bulge forming of tubular components

Abstract This paper presents a brief overview of developments in bulge forming of tubular components. A theoretical method of estimating the parameters such as internal pressure, axial load and clamping load required for the forming of tubular components as well as for the design of dies and tools is presented. In the discussion typical values of these parameters for particular tube size and material are presented and their implications on the design and operation of the process are noted.

Methods of wear testing for advanced surface coatings and bulk materials

Abstract This paper examines methods of assessing the wear resistance of coated and uncoated materials. Test equipment for sliding wear, erosion, impact and dynamic wear tests is discussed. Processes for measuring wear rates are highlighted and a simple procedure for conducting wear tests to simulate industrial wear problems is given. The wear test selected and the wear conditions encountered in real applications should conform in order for specialists to make adequate judgement on the life of a particular component in service.

Metal-matrix composites: Materials aspects. Part II

Abstract In Part I (Metal matrix composites: Manufacturing aspects) six different fabrication routes were discussed for manufacturing MMC materials, these being: PM, diffusion bonding, liquid-metal infiltration, squeeze casting, spray codeposition and compocasting. Amongst them, the squeeze-casting technique is used widely for the continuous production of MMC materials. MMC materials are produced with a mixture of matrix and reinforcement materials. In this paper an analysis of the matrix and the reinforcement is given and a potential solution is enumerated for selecting the proper matrix and reinforcement materials to form the MMC.

Magnetron sputtering of tin protective coatings for medical applications

Abstract Prostheses for implantation into the human body must be biocompatible i.e. no dissolution of the material can occur in human tissue and also, the prostheses must be corrosion resistant. Titanium nitride (TiN) possesses good mechanical, corrosion resistant, and aesthetic properties. It has also been found that such properties are not compromised in the oral cavity. Hence TiN can be readily utilised in dental prosthetics. TiN, an extremely inert compound was reactively sputtered in a closed field, unbalanced magnetron system. The substrates used included AISI 316L stainless steel. The analysis of these TiN coatings with respect to deposition parameters and their subsequent effect on corrosion resistance and porosity is outlined. Porosity before and after corrosion tests has also been examined.