Tibor Szalay

Multi-dexel based material removal simulation and cutting force prediction with the use of general-purpose graphics processing units

When the mechanistic cutting force model is applied for cutting force prediction during multi-axis milling, the accurate determination of the contact area between the cutter and the workpiece and the fast processing of the gained geometry data play an important role. During the evolution of the material removal simulation techniques the discrete z-map method has become the most widespread in this field, although it does not cover the whole cutter surface and its use requires the rearranging of the geometry data before the cutting force estimation. In this paper the reconstruction of the cutting force equations of the mechanistic model is proposed for the purpose of the direct consuming of the geometry data. To this end the multi-dexel based material removal simulation method is applied which provides general solution for the contact area determination on the whole cutter surface and gives more accurate result as opposed to the z-map method. The form of the introduced algorithms lets them being executed in a highly parallelized manner by general-purpose graphics processing units (GPGPUs), thereby increasing dramatically the performance of the simulation and the cutting force estimation as compared to the existing solutions.

Technological Aspects of the Electrical-Discharge Machining of Small-Diameter Holes in a High-Density Ceramic. Part 1

Results are presented from a study of the effect of the technological regimes used in electrical-discharge machining on the accuracy of small-diameters holes formed in parts made of a high-density ceramic. It is established that increases in the frequency and duration of the pulses in the electrical-discharge machining of holes in an oxide-carbide ceramic increase the diameter of the holes, deviations in their shape, and the diameter and height of the cone at the bottom of the holes. It was determined that it is necessary to optimize the electrical-discharge machining of small-diameter holes in high-density ceramics.

Experimental Investigation of Tool Breakage in Micro Drilling of EN AW-5083 Aluminium

Nowadays micro hole drilling is more and more applied machining operation. Because of less than 1 millimeter diameter, and of the relatively high thrust force, micro drills are more easily break than conventional ones. In this paper the experiences of micro drilling tests are summarize in order to demonstrate that measuring thrust force is efficient way to recognize the tool breakage. In order to evaluate the micro drill breakage monitoring method the authors carried out experimental measurements varying the cutting conditions, too.

Improvement of the mechanical properties of sintered metals by modifying the process parameters

Nowadays, there is a growing need for parts, which are made directly to final size because of the favorable cost of the production. However technologies that keep the high geometry accuracy and good mechanical properties are required such as moulding, forming or powder metallurgy. This is the reason, why these technologies are improved continuously. In the paper our research focused on the technology of the powder metallurgy is introduced. This paper gives a short survey about the mechanical properties of sintered metal components and their manufacturing technology. The goal of the introduced research is the improvement of the mechanical characteristics of the examined sintered metals by varying the process parameters, like material composition, compact density and sintering conditions. The authors explain the test methods, the experimental tests, and the results regarding the experiences.

Real-Time Cutting Force Prediction and Cutting Force Coefficient Determination during Machining Processes

In this paper a new method for instantaneous cutting force prediction is presented, in case of sculptured surface milling. The method is executed in a highly parallel manner by the general purpose graphics processing unit (GPGPU). As opposed to the accustomed way, the geometric information of the work piece-cutter touching area is gained directly from the multi-dexel representation of the work-piece, which lets us compute the forces in real-time. Furthermore a new procedure is introduced for the determination of the cutting force coefficients on the basis of measured instantaneous or average orthogonal cutting forces. This method can determine the shear and ploughing coefficients even while the cutting geometry is continuously altering, e.g. in the course of multi-axis machining. In this way the cutting forces can be predicted during the machining process without a priori knowledge of the coefficients. The proposed methods are detailed and verified in case of ball-end milling, but the model also enables the applying of general-end cutters.

Investigation of machinability of iron based metal matrix composite (MMC) powder metallurgy parts

One of the advantages of powder metallurgy technology is that we may produce the final geometry of the required part saving considerable time and cost. However there are several applications that require parts need additional machining for example when the product contains threads, cross bore or slots. In these cases cutting of the hard and porous material may causes difficulties in manufacturing. The aim of the introduced research is the experimental investigation of the machinability of the iron based MMC powder metallurgy parts, determining the favourable composition of the powder and advantageous process parameters regarding the properties of the machinability. The research try to answer to the challenge of the poorly defined expression: machinability, and after defining the features and methods of the evaluation we develop advises for the proper technology parameters.

Special Issues in Interactive Multimedia for Tele-Presence Operations

Abstract An active research and development co-operation has been established to formulate a consortium with academic and industrial partners to work on various aspects of digitising factory IT processes. This paper details some of the research activities devoted to implementing tele-presence features with interactive multimedia solutions.

A discrete simulation-based algorithm for the technological investigation of 2.5D milling operations

Many applications are available for the syntactic and semantic verification of NC milling tool paths in simulation environments. However, these solutions – similar to the conventional tool path generation methods – are generally based on geometric considerations, and for that reason they cannot address varying cutting conditions. This paper introduces a new application of a simulation algorithm that is capable of producing all the necessary geometric information about the machining process in question for the purpose of further technological analysis. For performing such an analysis, an image space-based NC simulation algorithm is recommended, since in the case of complex tool paths it is impossible to provide an analytical description of the process of material removal. The information obtained from the simulation can be used not only for simple analyses, but also for optimisation purposes with a view to increasing machining efficiency.

Analysing and Optimizing 2.5D Circular Pocket Machining Strategies

Though the circular pocket milling seems to be an old manufacturing task, it is nice to have thorough investigation among the different machining strategies, because in spare part production a frequent repeatable shape behaviour. As usual, at pocket milling the roughing operation is critical, because the excess material is in a closed area to the shape thus not possible to fix optimal cutting parameters for the whole area. In this exercise, we will deal with how the NC operational cycles and CAM systems could organize tool paths for circular pockets. This question is very important for the users because the selected strategy will influence the machining time and the tool life which determines the machining cost. In this article, several strategies were been compared through simulation and metal cutting experiments. During experiments, the material removal rate, the cutter engagement, and the cutting force were investigated alongside the tool path. At optimal tool paths, these parameters should be constant, because thus the cutting tool could provide maximum efficiency. It is found during experiments that the pocketing strategies used nowadays are far away from the optimal, and only the CAM-generated tool path strategies can execute the acceptable. The reason is because the tool path generation methods are made based on the part geometry without considering the technological aspects. In this article analysis of current, available strategies were been made, but over that two own-developed algorithms based on technological parameters were been discussed focused on optimal tool path to achieve maximum productivity.

Tool condition monitoring in micro-drilling using vibration signals and artificial neural network: Subtitle: TCM in micro-drilling using vibration signals

Tool condition monitoring is one of the key issues in mechanical micromachining for efficient manufacturing of the micro-parts in several industries. In the present study, a tool condition monitoring system for micro-drilling is developed using a tri-axial accelerometer, a data acquisition and signal processing module and an artificial neural network. Micro-drilling experiments were carried out on an austenitic stainless steel ((X5CrNi 18-10) workpiece with the 500 μm diameter micro-drill. A three-axis accelerometer was installed on a sensor plate attached to the workpiece to collect vibration signals in three directions during drilling. The time domain “root mean square” feature representing changes in tool wear was estimated for vibration signals of all three directions. The variations of the rms micro-drilling vibrations were investigated with the increasing number of holes under different cutting conditions. An artificial neural network (ANN) model was developed to fuse the rms values of all three directional vibration signals, the spindle speed and feed parameters to predict the drilled hole number. The predicted drilled hole number obtained with the ANN model is in good agreement with the experimentally obtained drilled hole number. It has been also shown that the error of hole number prediction obtained by the neural network model is less than that obtained by using the regression model.