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The Application of Laser Cladding to Marine Crankshaft Journal Repair and Renovation

This article presents the development and design of a laser cladding machine for in-situ marine diesel engine crankshaft repairs. The described technology and device is designed to perform crankpin journal renovation operations directly in the engine housing, without removing the crankshaft from the engine. This paper outlines the novel, in-situ concept of applying laser cladding to marine crankshaft repairs. Laser cladding technology is described along with the state of laser cladding implementation in modern production engineering. The principal design of the in-situ laser cladding machine is presented and accompanied by a detailed description of the in-situ laser cladding machine construction. Arguments for the selection of appropriate laser nozzles are provided based on state-of-the-art technology. Technological challenges deriving from the industrial use of the laser equipment are outlined. The proposed device and method satisfy ship-board crankshaft surface renovation needs and open up an entirely new dimension for the industrial application of laser cladding technologies. This technology provides clear economic benefits and many technological advantages.Copyright

Experimental analysis of end mill axis inclination and its influence on 3D areal surface texture parameters

The surface quality of machined parts depends highly on the surface texture that reflects the marks of the tool during the cutting process. The traditional theoretical approach indicates that these marks are related to the cutting parameters (e.g. cutting speed, feed, depths of cut), the machining type, the part material, the tool, etc. The influence of these factors has been widely studied by researchers and they have been considered in milling process models proposed to predict the final surface texture. Nevertheless, if an accurate prediction is desired, these milling models must include different geometrical errors influencing the cutting edges path on the part. In this paper, we present the results of a study showing the influence of real mill-axis inclination on 3D surface texture. Therefore, experiments with simple, end mill tool operation, with constant cutting parameters and four different cutting directions (the directions that we labelled as North, South, East, and West) in accordance with the machine coordinate system were performed. Using optical 3D areal surface texture measurement techniques with the Bruker Contour device, we obtained areal surface texture parameters for analysis. Descriptive statistical analysis and one-way ANOVA analysis were performed to detect the factor significances and their influence on 3D areal surface texture parameters. The results from ANOVA and graphical analysis clearly identified tool-axis inclination in the South and East directions. If a relationship between tool-axis inclination and surface texture parameters can be demonstrated, this calculation can be included in the model of 3D surface texture formation. Improving the mathematical model with all possible errors occurring in high speed machining operations helps to obtain more precise surface height parameter Sz results for simple end mill operation. The model is suitable for complicated machining operations with ball end mill tools.

The Dependence of 3D Surface Roughness Parameters on High-Speed Milling Technological Parameters and Machining Strategy

High-speed milling is an effective machining method extensively used in modern material processing. This machining method offers increased efficiency, quality and accuracy of the machined surface as well as considerably reducing overall production costs and machining time. This paper outlines comprehensive research into the impact of the technological strategy and processed materials on carefully selected 3D surface roughness parameters. This research provides manufacturers who use high-speed milling with recommendations on how to better obtain the desired surface roughness parameters. More specifically, it covers multifactorial analysis of the following factors: feed rate, manufacturing strategy, overlap and material influences on the most characteristic 3D surface parameters. The results are based on ANOVA – analysis of variance, where differences between groups of means are analysed using a range of statistical models.Subsequent analysis and respective conclusions identify the most significant factors as being the material and high-speed milling manufacturing strategy. Analytically justified recommendations for manufacturers regarding the preferred high-speed milling strategies are provided.The research concluded that the values of the selected 3D surface roughness parameters in high-speed milling depend significantly on the type of material being machined, milling mode and cutting tool overlap as well as feed. In particular, Sa - the arithmetic mean height, is highly sensitive to the milling mode.Copyright