Papers by Keyword: Machined Surface

Abstract: This study focused on cutting trace control for machining three-dimensional contours, such as molds, with high accuracy and efficiency. In this study, experiments were conducted to generate a honeycomb structure with hexagonal cutting marks and a lattice structure with square cutting marks in the cutting process of a two-blade ball-nose end mill using a runout adjustable holder, with the aim of adapting the cutting-mark control to the production level. In this study, the relationship between runout, machined surface, and cutting force is shown, and the effects of runout, honeycomb structure, and lattice structure on surface adsorption are investigated and evaluated for applications in the production field.

Abstract: Progressive electrical discharge machining technology is characterized by a high degree of quality of the machined surface. The high achieved quality of the machined surface not only in terms of roughness parameters but also in terms of geometric shape is practically a matter of course with this machining technology. Nevertheless, in certain specific cases, geometric deviations of the shape occur, even when the most modern and highly sophisticated electrical discharge equipment are used. One of the frequently occurring geometric inaccuracies of the shape when applying progressive electrical discharge machining technology with a wire tool electrode is the deviation of circularity. Therefore, the aim of the conducted experimental research was to identify these shortcomings in the first place and also to describe in which specific cases these deviations occur. Subsequently, based on the obtained results of experimental measurements, propose appropriate measures for their elimination or at least their minimization.

Abstract: This study investigated the effects of tool runout on chatter vibration taking images of a machined surface to assess the vibration strength, number of vibrations, and phase difference depending on the spindle speed and axial depth of the cut. This study obtained significant results regarding the stability pocket represented by the spindle speed. We observed that the stability limit changed depending on tool runout.

Abstract: Geometrical precision machined surface is generally understood as mainly precision shape, orientation, location and run-out. As a rule, it is measuring the appropriate deviations from the nominal surface. The geometric size of this deviation from the nominal surface can in practice affect the conventionally measured value for the dimension and the dimension whilst maintaining the required tolerance. Because the WEDM technology is among the most accurate technology, the small final geometric accuracy deviation has also a negative impact on the final quality of the machined surface. The paper aimed to describe errors geometrical precision of machined surface which occurs in wire electrical discharge machining (WEDM) and quantify their scope.

Abstract: A novel Micro Electro Mechanical System (MEMS) measurement device for straightness measurement with a three point method has been proposed. This device integrates three cantilever displacement sensors with a narrow pitch on a silicon chip. The authors determine appropriates shape, dimensions of the cantilever, and a fabrication process. According to simulation results, a triangular cantilever with altitude 12 mm long, base 4mm long, and 0.25 mm thickness was adopted to realize the target measuring range of 100 μm. Near the end of each cantilever, a square frustum probe 250 μm high which was fabricated by anisotropic wet etching was placed. Near the base of cantilevers, four piezo resistance gauges were formed; two are active gauges for measuring stress arise from a displacement at the probe and the others are dummy gauges for temperature compensation. Wiring and contact terminals were fabricated on the base substrate and the total size of the device is 20 mm × 32 mm. The fabrication process of this device was designed and result of a trial production was reported.

Abstract: Chatter vibration in end milling remains a serious problem for manufacturing engineers. Chatter vibration often leaves a characteristic pattern or chatter mark on the machined surface. Chatter marks are generated by the relative displacement of the tool and the workpiece. Closer observation of chatter marks may prove useful in understanding chatter vibration. In this study, we investigated chatter mark patterns on end-milled surfaces. Based on these observations, we proposed and demonstrated the effectiveness of an iterative analysis method to identify stable machining conditions and minimize chatter vibration in various operations without use of sensors under specific conditions.

Abstract: The surface acoustic wave (SAW) technique is a precise and nondestructive method to detect the mechanical characteristics of the precision-machined surface. The paper is concerned with the effect of the roughness of the machined surface on the dispersion of surface acoustic waves propagating in the precision-machined surface which indicates mechanical characteristics of the machined surface. The finite element method (FEM) is employed by establishing a series of models with different roughness Ra value to analyze influences from different roughness Ra value on surface acoustic wave dispersion. The models are established by applying a combined method based on fractal theory and wavelet analysis. The simulation results showed that the roughness of machined surface will cause the dispersion of surface acoustic wave propagation, the effect varies with the different roughness Ra values. A critical Ra value influencing on the surface acoustic wave propagation exists. Accordingly, that the factor of roughness should be considered in advance or not, the situation can be determined through studying and determining the critical roughness Ra value above mentioned. Consequently, the study has the important meaning regarding the detection for mechanical characteristics of the machined surface.

Abstract: Chatter vibration generated by coupling a work-piece, machine tools, and cutting tool is a serious problem for engineers. A regular pattern forms the machined surface when chatter vibration occurs. There must be a direct relationship between the relative displacement and machined surface. We propose a method for controlling chatter vibration of end-milling from a machined surface. Hammering tests were first carried out to determine the natural frequencies of machine tools and the tool system, which are likely to be the cause of vibration. We also propose a technique of applying reverse analysis to end-milling surfaces. The machined surface is assumed to include an essential index to easily control chatter vibration at the factory. We found that chatter vibration occurs near the frequency of the cutting tool, tool holder, and their coupling, not at the natural frequency, and the chatter vibration frequency can be calculated by analyzing the surface pattern and cutting conditions. Moreover, the proposed method was effective in analyzing chatter vibrations including more than two kinds of natural frequencies at the same time.

Abstract: Shape memory alloys (SMAs) are now widely used in many industrial and engineering applications e.g. in aircrafts, space vehicles, robotics and actuators. However the available literature reveals that little or no work is published on the machinability of these alloys. In this paper, the effect of the main cutting parameters namely: cutting speed, depth of cut and feed rate on the surface quality of the machined surface of the Cu-Zn-Al shape memory alloy both in the cast and after direct extrusion using a CNC milling is investigated. The cutting speed was varied from 750 to 2000 rpm , the depth of cut was varied from 1 to 4 mm and the feed rate was varied from 100 to 250 mm/min. Furthermore, the general microstructure, the mechanical behavior and hardness of the Cu-Zn-Al shape memory alloy both in the cast and after direct extrusion are determined and discussed. It was found that the best achieved surface quality in this SMA, machined within the different investigated cutting conditions is 0.13 microns at cutting speed of 750 rpm, 1 mm depth of cut and 150 mm/min. feed rate, which is better than the surface quality achieved in other materials at the same cutting conditions.

Abstract: Today, the study of surface integrity became a growing and multidisciplinary branch of science. Its purpose is to gain such understanding of the surface which can be exploited in real-world applications and in commercial services. The importance of the surface was and continues to be the topic of a number of highly specialized papers. However, the surface has not been yet evaluated in terms of multiple factors in order to obtain a comprehensive picture of its condition and to reveal the interrelationship between the manufacture of the surface and its resulting properties. The paper gives a description of effects of special cutting tools on the structure of the sub-surface region. These structural changes will be explored by means of metallographic observation, hardness measurement and evaluation of residual stresses.