This Master’s thesis process list of different finite element programs, which allows us to simulate process of material separation. We estimated their advantages and disadvantages in the end. In program ANSYS Ls-Dyna was created 3D model, in which we simulate process of orthogonal splinter machining and we study dependence of changes different input parameters (tool geometry, depth of cut, cutting speed) on the chip form and forces rate between tool and workpiece.

The material removal process uses cutting tools in order to produce the desired shape of the workpiece. Tool wear has been a problem for cutting tools, since cutting tools wear and break. Research has been accomplished in the tool wear field for tool life and more recently tool wear. The computer generation has created a method to simulate the material removal process. These computer simulations model the cutting tool reaction with the workpiece. Many of the simulation models use finite element analysis to calculate the reaction of the cutting tool. Different finite element models are being used throughout the world for research. This thesis used an updated Lagrangian model in conjunction with Archard's law to predict the wear of the cutting tool. This research used experimental data to correlate with simulation data to see whether or not Archard's law was a good approximation for tool wear. The research used different side rake angles and cutting surface speed to test the simulation. Shear angle, contact length, cutting ratio, and force are used to provide output values to compare the experimental and computer simulation data. The comparative results showed good trends between the experimental and computer simulation data in every comparison. The results also showed a good approximation for the force and contact length values. Archard's law can be used to model wear on cutting tools with further research.

The research objectives of this thesis are as follows: (1) Investigate the effects of carbon content, alloying, and heat treatment of steels on white layer formation, (2) Prove/disprove that the temperature for phase transformation in machining is the same as the nominal phase transformation temperature of the steel, (3) Quantify the contributions of thermal and mechanical effects to white layer generation in machining, (4) Develop a semi-empirical procedure for prediction of white layer formation that accounts for both thermal and mechanical effects. These research objectives are realized through experimental and modeling efforts on steels. Depth and hardness measurements of the white layers formed in steels show the importance of heat treatment and carbon content on white layer formation. Measurements of workpiece surface temperature and X-Ray Diffraction characterization of the machined surfaces show that phase transformation occurs below the nominal As temperature suggesting that mechanical effects play an important role in white layer formation. The maximum workpiece surface temperature, the effective stress, and plastic strain on the workpiece surface are measured and/or calculated and shown to affect the white layer depth and amount of retained austenite. A semi-empirical procedure is developed by correlating the maximum workpiece temperature and the unit thrust force increase with white layer formation.

The surface integrity of a machined component that meets the demands of a specific application requirement is defined by several characteristics. The residual stress profile into the component is often considered as the critical characteristics as it carries a direct effect on the fatigue life of a machined component. A significant amount of effort has been dedicated by researchers to predict post process stress in a workpiece using analytical, experimental, and numerical modeling methods. Nonetheless, no methodology is available that can express the cutting process parameters and tool geometry parameters as functions of machined residual stress profile to allow process planning in achieving desired residual stress profile. This research seeks to fill that void by developing a novel approach to enable the extraction of cutting process and tool geometry parameters from a desired or required residual stress profile. More specifically, the model consists in determining the depth of cut, the tool edge radius and the cutting forces needed to obtain a prescribed residual stress profile for an orthogonal machining operation. The model is based on the inverse solution of a physics-based modeling approach of the orthogonal machining operation and the inverse solution of the residual stress prediction from Hertzian stresses. Experimental and modeling data are used to validate the developed model. The work constitutes a novel approach in engineering residual stress in a machined component.

This thesis presents results from the application of cryogenic cooling on multiple-pass friction stir processing and the subsequent orthogonal machining on friction stir processed and as-received Mg AZ31B-O disks, and shows their combined effects on microstructure and microhardness values. A simple friction stir tool, a specially designed fixture and liquid nitrogen are used to perform multiple-pass friction stir processing experiments on Mg AZ31B-O alloy. The friction stir processed and as-received sheets are then made into disks for the orthogonal machining experiments. This study analyzes the microhardness, microstructure changes by cryogenic friction stir processing and the effect of machining conditions such as dry, MQL and cryogenic and cutting parameters on the Mg AZ31B-O alloy. Four different speeds and three different feed rates are used for the orthogonal machining experiments. The effects of stirring parameters such as the translational feed, rotational speed, cooling conditions and the machining parameters are studied. The resulting microstructure and microhardness from these processes hold a key to the mechanical properties of the alloy. This analysis would help to understand and evaluate the specific aspects of grain size and microhardness that influence the fatigue life of a component.

Master of Science / Industrial & Manufacturing Systems Engineering / Shuting Lei / Transparent brittle materials such as glass and silicon dioxide have begun to replace the conventional materials due to the advantageous properties including high strength and hardness, resistance to corrosion, wear, chemicals and heat, high electrical isolation, low optical absorption, large optical transmission range and biocompatibility. However because these materials are extremely hard and brittle, development of an ideal machining process has been a challenge for researchers. Non-traditional machining processes such as abrasive jet and ultrasonic machining have improved machining quality but these processes typically results with issues of poor surface integrity, high tool wear and low productivity. Therefore a machining technique that overcomes the disadvantages of existing methods must be developed. This study focused primarily on improving the machinability and attaining crack-free machined surfaces on transparent brittle materials by inducing micro cracks or seed damages on the subsurface of the materials. The hypothesis was that micro-cracks induced by femtosecond laser would synergistically assist the material removal process by a cutting tool by weakening or softening the material, followed by conventional machining process. Laser induced damages due to varying laser intensities and at different depths in bulk BK7 glass was studied in order to select the optimal laser machining conditions for the experiments. Dimensional and structural profiles of laser cracks are observed using an optical microscope. A comparative study of machined untreated BK7 samples and damage induced BK7 samples was conducted. Due to its simple process kinematics and tool geometry, orthogonal machining is used for the study. Results showed that machining laser-treated samples caused an average 75% force reduction on comparison to machining of untreated samples. Laser treated machined samples were produced without subsurface damages, and reduced tool wear was noted. Overall improved machinability of BK7 glass samples was achieved.