Marek Vrabel

Finite Element Simulation of Cutting Forces in Orthogonal Machining of Titanium Alloy Ti-6Al-4V

In this paper, a Lagrangian finite element-based machining model is applied in the simulation of cutting forces in two-dimensional orthogonal cutting of titanium Ti-6Al-4V alloy. The simulations were conducted using 2D Finite Element Method (FEM) machining simulation software. In addition, the cutting experiments were carried out under the different cutting speed, feed and tool geometry (rake angle, clearance angle and cutting edge radius). The effect of cutting speed, feed and tool geometry on cutting force were investigated. The results obtained from the finite element method (FEM) and experimental studies were compared.

Effect of Honing Parameters on Generated Surface Quality of Cylinder Liner within Automotive Engine Production

One of the key parameter in evaluation of cylindrical surface quality of the engine liners is surface roughness. A large number of process factors affecting a final surface topography, which has direct impact on fuel consumption and CO2 emission. A suitable choice of honing conditions can results not only to better surface quality, but it can contributes to reducing of environmental impacts in automobile transport. Twelve different engine cylinder liners were machined in various combinations of cutting parameters. Experimental testing was realised on real production machine tool, where process factors were cutting speed, machining allowance and stone pressure of honing tool. All factors have 4 levels and parameters of surface roughness CR, CF, CL were selected as a variables and suitable indicators for surface quality assessment. The results show that influence of the tool stone pressure on honed surface is more significant than effect of cutting speed. Effect of machining allowance is negligible as well.

Adaptive Control System to Assist the Surface Workpiece Quality when Drilling

Article deals with design of adaptive control system for drilling process of aerospace critical components. The system proposed in this paper is directed towards real the time control of surface roughness parameter Ra. Proposed model for monitoring and control consists of surface roughness prediction system and decision making subsystem. The artificial neural network was employed to calculate surface roughness parameter Ra through of process monitoring indices such as torque Mz, force Fz, power P and cutting conditions feed f, cutting speed vc. Test samples were nickel based super alloy Udimet 720 used as a basic constructional material of discs for gas turbine engines.

Evaluation of Relationship between Cutting Parameters and Torque in Hole Making of Titanium Alloy

In terms of machinability are titanium alloys classified in the group of difficult to cut materials. The main factors determining this status are limited tool life, high generated cutting forces (torque) and temperature in cutting zone caused by low thermal conductivity as well as chemical reactivity with cutting tool. Solid carbide drills still remain as preferred choice in hole making process when machining Ti6Al4V alloy. Besides cutting conditions, tool and cutting edge geometry significantly affect the value of torque. Reduction of process energy requirements can be achieved by appropriate optimization of these parameters. Mathematical model describing influence of cutting speed, feed rate, clearance angle and cutting edge radius on investigated variable with high reliability coefficient (R2=96.72%) was found. Drilling experiments were designed and carried out using Taguchi orthogonal array L16.

Types of Tool Wear of AlTiN Coated Cutting Insert after Machining of Weld Overlay

Authors of the paper present different types of tool wear after machining of weld overlay with AlTiN cutting insert. Welded layer was created on roller made from S355J0 steel by Open Arc (OA) method also referred as Metal One Gas (MOG). Various forms of tool wear were documented by optical microscope. Microchipping of cutting edge, built up edge (BUE) and flank wear were identified on examined round insert in rough turning of hard cladding.

Investigation of the Surface Quality when End–Ball–Milling Form Surfaces with Sequence of the Radii Ratio

This paper deals with a methodology of identifying surface quality when endball milling form surfaces which are applied in tool making. This methodology was developed for the 3D milling process and it consists of following parts as design of the samples, surface milling and checking surfaces with different sequence of radii ratio. That sequence was used to model real form surfaces applied in tool making. Based on the defined measurability of the surface roughness, two milling strategies have been applied to produce radii sequence. In order to prevent undesired cusp formation in the 3D milling, the response surface methodology and statistical analysis are used to evaluate surface quality.

Influence of Tool Path Orientation on the Surface Roughness when End Ball Milling Rounded Surfaces

Paper deals with relationships affecting surface roughness in three dimensional milling. Because of definite curvature of the machined surface, three milling strategies based on single direction have been examined in end ball milling process. Research is based on fragmentation of the definite surface curvature into form of the patches being machined. Patches have been set through normal vectors and related axes of motion of the end ball milling cutters. Surface quality has been identified under influence of cutting speed, feed rate and side step of milling cutters. Simple geometrical models of the resultant cusp height are compared with the measured data.

Effect of Workpiece Hardness on Surface Microgeometry when Hard Turning with Ceramic Inserts

Hard turning provides an alternative to grinding in some finishing operations. This paper deals with analysis of part surface finishing when turning hardened steel heat-treated on hardness of 46, 55 and 60 HRC with mixed oxide ceramic inserts. Average surface roughness Ra has been widely used in industry it is known that the single parameter Ra is inadequate to define the functionality of a surface. Two different surfaces with similar values of Ra can behave differently under loading conditions. The surface profile 2D and 3D parameters are assessed. The influence of workpiece hardness on surface roughness parameters and cutting force components is investigated. Results show that finish hard turning with mixed ceramic tool produces surface profile comparable to those produced by grinding.

Surface Roughness Modeling and Prediction by ANN when Drilling Udimet 720

Article deals with design of artificial neural network (ANN) for prediction of the surface roughness as one of the important indicators of machined surface quality. Back propagation neural network was trained and tested for prediction of the machined surface roughness. Cutting conditions, selected monitoring indices and tool wear parameter were given as inputs to the ANN. Test sample was nickel based super alloy Udimet 720, which is used as material for highly stressed jet engine components. Experimental data collected from tests were used as input into ANN to identify the sensitivity among cutting conditions, monitoring indices and progressive tool wear and machined surface roughness.