André J. Souza

Evaluation of Machining Forces in Asymmetrical Face Milling of Cast Iron DIN GGG50

The effects of the feed rate and the axial and radial depth of cut in the up and down asymmetrical face milling with respect to workpiece about the orthogonal components (axial, radial and tangential) of the cutting force in the machining of cast iron DIN GGG50 with carbide inserts was evaluated. The spindle speed was remained constant. The cutting forces were acquired through a sensory system that consists of piezoelectric dynamometer, signal acquisition board and computer with appropriate software. In the end it was concluded that studies of machining forces provides a strong basis for understanding the kinematics and the dynamics of the tool and the cutting operation and it can be applied to optimize the cutting geometries and test the probabilities of tool distortions.

Optimization of Cutting Parameters for Face Milling of Cast Iron by Reducing Specific Cutting Energy and Machined Surface Roughness

The search for continuous improvement of the processes and products offered to the market combined with continuous efforts to reduce energy consumption stimulates the development of techniques and tools geared towards their optimization. Thus, this manuscript describes the application of multivariate optimization in the process of face milling of DIN GGG 50 nodular cast iron by means of experimental design techniques, regression models, and Taguchi loss function. Three input parameters (axial “ap” and radial “ae” depth of cut, and feed-rate “f”) were used as controllable factors of the process and two output parameters (specific cuttingenergy “es” and roughnessaverage “Ra”) were considered as response variables. The output obtained as a result of optimization wases = 1.41 J/mm3and Ra = 0.85 µm by applying the input parameters ap = 2.34 mm,ae = 33.4 mm and f = 0.44 mm/rev.

Empirical Determination of Roughness Parameters Using Wiper Tool Inserts in Finish Turning of AISI 4140

The surface finishing resulting from metal cutting processes is associated with the surface texture and integrity. Texture can be quantified by roughness parameters as Roughness Average (Ra), Total Roughness (Rt), Maximum Surface Depth (Ry) and Surface Depth (Rz) which are directly related to cutting magnitudes and tool characteristics. This work assesses empirically the roughness generated by wiper cutting tools in dry finishing turning operations of AISI 4140 steel. By keeping a constant cutting speed and using depths of cut greater than 2/3 of the cutting tool radius (rε), four feed rates (f) are used with three rε, both combined in a way to ascertain the equations which allows the evaluation of Ra, Rt, Ry and Rz values. In order to determine the equations for roughness prediction a multiple linear regression method in function of f and rε is applied, showing good agreement with experimental results. Also, achieved results allows to prove the effectiveness of wiper tools to generate excellent surface finish without grinding operations and consequently showing that its use can increase significantly the material removal rate without compromising the surface roughness in high feed rate operations.

Comparative Analysis on Wiper and Standard Tools in Dry Finish Turning of Martensitic Stainless Steel AISI 420

Machining performance consists to associate the optimal process and cutting parameters and maximum material removal rate with the most appropriate tool while controlling the machined surface state. This work verifies the influence of standard and wiper cutting tools on generated surface roughness and residual stress in dry finish turning operation of the martensitic stainless steel AISI 420 in a comparative way. Tests are conducted for different combinations of tool nose geometry, feed rate and depth of cut being analyzed through the Design of Experiments regarding to surface roughness parameters Ra and Rt. Moreover, the formation of residual stresses in the material (using the technique of X-Ray Diffraction) was evaluated after the machining process for these two cutting geometries and thereafter the result was compared between them. An ANOVA is performed to clarify the influence of cutting parameters on generated surface roughness, which outputs inform that cutting tool geometry is the most influent on Ra and Rt. It is concluded that analyzed wiper inserts present low performance for low feed rates. Regarding the analysis of the residual stresses it can be stated that for standard and wiper tools the values collected show that for finish turning the compression stresses were found. It can be observed that the greatest amount of compressive stress has been found for the standard tool.

Tool-Life of Wiper and Standard Cutting Tool in Finish Turning of SAE 4140

Vibration tendency can rise in turning process when selecting a cutting tool with larger nose radius and/or increasing the feed rate. As consequence, it may affect the process performance by reducing the tool-life and causing damage to the machined surface finish. Moreover, the generated surface roughness strongly depends on the relation between feed rate and cutting tool nose radius. The wiper cutting tool is a recent technological advancement which is claimed to allow both the feed rate and the depth of cut to be doubled while maintaining the same surface finish value in comparison with standard tools. Thus, the objective of this paper is to benchmark tool-life of standard and wiper cutting tools in dry finish turning of SAE 4140 steel. The analysis consists of successive measurements of workpiece roughness and tool corner wear after each turning pass while using combined machining parameters for a target roughness average value close to 2 μm with both inserts being used under the manufacturers recommended cutting conditions. It is noted that the two inserts presented good performance both in the workpiece finish and in tool-wear.