An investigation on formation of burrs during milling of aluminium alloy under wet condition

Undesirable burrs are created out of a machining process. The objective of the present work is to explore the suitable condition to obtain no burr, or negligible burr, around the edge of a machined product at wet condition. Face milling experiments have been carried out on blocks made of aluminum alloy (Alloy-4600M) with a single, coated-carbide inserted cutter for observing the nature of burr formation. Depth of cut has been maintained constant at 3 mm for all sets of experiments. In each experiment set, three cutting velocities (170 m/min, 237 m/min and 339 m/min) and three in-plane exit angles of 30°, 60° and 90° are provided at three different feeds of 0.08 mm/tooth, 0.1 mm/tooth and 0.12 mm/tooth. First set of experiments are done without any exit edge bevel. Similar sets of experiments are carried out with 15° and 30° exit edge bevel angles to find out the condition for minimum burr. The bevel is made of a height of 3 mm. In the present experimental investigation, a minimum burr height of as low as 3 micron is obtained at an in-plane exit angle of 30° and exit edge bevel angle of 15° under the machining condition of 339 m/min cutting velocity and 0.1 mm/tooth feed.

Influence of Circumferential Placement Position of Guide Vanes on Performance and Dynamic Characteristics of Nuclear Reactor Coolant Pump

In order to study the influence of the circumferential placement position of the guide vane on the flow field and stress-strain of a nuclear reactor coolant pump, the CAP1400 nuclear reactor coolant pump is taken as the research object. Based on numerical calculation and test results, the influence of circumferential placement position of the guide vane on the performance of the nuclear reactor coolant pump and stress-strain of guide vanes are analyzed by the unidirectional fluid-solid coupling method. The results show that the physical model and calculation method used in the study can accurately reflect the influence of the circumferential placement position of the guide vane on the nuclear reactor coolant pump. In the design condition, guide vane position has a great influence on the nuclear reactor coolant pump efficiency value, suction surface of the guide vane blade, and the maximum equivalent stress on the hub. However, it has a weak effect on the head value, pressure surface of the guide vane blade, and the maximum equivalent stress on the shroud. When the center line of the outlet diffuser channel of the case is located at the center of the outlet of flow channel of the guide vane, it is an optimal guide vane circumferential placement position, which can reduce the hydraulic loss of half of the case. Finally, it is found that the high stress concentration area is at the intersection of the exit edge of the vane blade and the front and rear cover, and the exit edge of the guide vane blade and its intersection with the front cover are areas where the strength damage is most likely to occur. This study provides a reference for nuclear reactor coolant pump installation, shock absorption design, and structural optimization.

Finite Element Analysis and Statistical Optimization of End-Burr in Turning AA2024

This contribution presents three-dimensional turning operation simulations exploiting the capabilities of finite element (FE) based software Abaqus/Explicit. Coupled temperature-displacement simulations for orthogonal cutting on an aerospace grade aluminum alloy AA2024-T351 with the conceived numerical model have been performed. Numerically computed results of cutting forces have been substantiated with the experimental data. Research work aims to contribute in comprehension of the end-burr formation process in orthogonal cutting. Multi-physical phenomena like crack propagation, evolution of shear zones (positive and negative), pivot-point appearance, thermal softening, etc., effecting burr formation for varying cutting parameters have been highlighted. Additionally, quantitative predictions of end burr lengths with foot type chip formation on the exit edge of the machined workpiece for various cutting parameters including cutting speed, feed rate, and tool rake angles have been made. Onwards, to investigate the influence of each cutting parameter on burr lengths and to find optimum values of cutting parameters statistical analyses using Taguchi’s design of experiment (DOE) technique and response surface methodology (RSM) have been performed. Investigations show that feed has a major impact, while cutting speed has the least impact in burr formation. Furthermore, it has been found that the early appearance of the pivot-point on the exit edge of the workpiece surface results in larger end-burr lengths. Results of statistical analyses have been successfully correlated with experimental findings in published literature.

Analysis of mechanics around a localised surface defect of cylindrical roller bearing

In the paper, in order to investigate the mechanics around a localised surface defect of cylindrical roller bearing, a dynamic model is built based on the model proposed by Gupta to calculate the carrying loads of rollers when the rollers pass over the defect zone under different circumstances. A defect model is built by the finite element method to calculate the stress distribution around the defect. Three stages are defined to simplify the analysis of mechanics in this process. With the increase of the rotor speed, the stress received by the exit edge increases. The increase of the radial load or defect length leads to the increase of stresses in all stages. When the defect position deviate from the centre line and is close to the edge, the stress received by the exit edge on the surface increases but the sizes of stress on the subsurface decrease.

Observation of Drilling Burr and Finding out the Condition for Minimum Burr Formation

Suppression or elimination of burr formation at the exit edge of the workpiece during drilling is essential to make quality products. In this work, low alloy steel specimens have been drilled to observe burr height under different machining conditions. Taper shank, uncoated 14 mm diameter HSS twist drills are used in these experiments. Dry environment is maintained in experiment set I. Water is applied as cutting fluid in experiment set II. In the next four sets of experiments, the effect of providing back-up support material and exit edge bevel is observed on formation of burr at the exit edge of specimens under dry and wet conditions. It is revealed that an exit edge bevel of 31 degrees with water as the cutting fluid gives negligible burr at the exit edge of the drilled hole at certain machining conditions. Use of a back-up support can also reduce drill burr to a large extent. In this paper, artificial neural networks (ANN) are developed for modeling experimental results, and modeled values show close matching with the experimental results with small deviations.

Experimental Study on Exit Edge Defects in Two Dimension Cutting of SiCp/Al Composites

In this paper, the influence of the tool rake angle, cutting depth and cutting speed on exit edge defect sizes are discussed by the two dimension cutting experiment of SiCp/Al composites. The sizes are measured by using the Keyence VHX-1000C type super preview 3D microscopy. The results indicate that exit edge defect sizes are influenced greatly by tool rake angle and cutting depth, and are influenced slightly by the cutting speed. The edge defect sizes have an overall downward trend when the tool rake angle is smaller than 5°, and have an apparent upward trend when the tool rake angle (γ0) is 10°.The length (L), height (H) of exit edge defects and the negative shear angle increase with increasing of the cutting depth.

Burr Minimization in Shaping of Aluminium Alloy-Through Experimental and Stress Analysis Approach

Shaping Burrs are produced at the edge of a workpiece when a cutter exits it. It causes difficulties in manufacturing and assembly stages. Several attempts were made to minimize burr to suppress deburring to improve productivity. Deburring of the surface in shaping operation in railways industry and other industries is a great problem. An investigation on burr formation at the exit edge of aluminum alloy (4600-M) flats in shaping operation is done in this work under dry environment. It is found out that burr is negligible at 150 exit edge bevel angle. Distribution of shear stress is analyzed using FEM to validate the experimental results. It is found that maximum equivalent stress and deformation at different points on the 150 exit edge bevel angle become minimum justifying the experimental observation. Hence, an exit edge bevel of 150 may be adopted to have minimum burr formation.