Advanced Materials Research Vol. 797

Abstract: Data-mining methods using hierarchical and non-hierarchical clustering are proposed that will help engineers determine appropriate end-milling conditions. We have constructed a system that uses clustering techniques and tool catalog data to support the determination of end-milling conditions for different types of difficult-to-cut materials such as austenitic stainless steel, Ni-base superalloy, and titanium alloy. Variable cluster analysis and the K-means method were used together to identify tool shape parameters that have a linear relationship with the end-milling conditions listed in the catalogs. The response surface method and significant tool shape parameters obtained by clustering were used to derive end-milling condition decision equations, which were used to determine the indicative end-milling conditions for each material. Comparison with the conditions recommended by toolmakers demonstrated that our proposed system can be used to determine the cutting speeds for various difficult-to-cut materials.

Abstract: In order to increase tool life and workpiece surface quality, cutting processes with geometrically defined cutting edges demand inserts with a targeted prepared edge. For example, chamfers are largely used in many processes to provide edge strengthening without damaging the chip flow. In order to achieve a stable and reliable cutting process, small and uniform chamfers are necessary. In this context, the influence of grinding parameters on the edge quality and on the chamfer width deviations is investigated. It was found that larger abrasive grains increase edge chipping and that elastic deformation during chamfer grinding at insert corner radius is the main responsible for chamfer width deviation.

Abstract: This paper presents the important characteristics of material removal mechanism during single grit scratching test. Material removal mechanism in these scratches shows cutting and ploughing action varies with the number of cutting edges leading to different cutting force and specific energy. According to experimental results, single edge scratches are more efficient cutting while multiple edge scratches give more ploughing actions, which consume energy with little contribution to materials removal. The results provided an important insight of material removal during grinding process.

Abstract: ts difficult to guarantee the surface quality when processing the carbon/silicon carbide (C/SiC) composites, and also easy to produce burr defect. So firstly the law of the burrs generated on different direction of fiber was analyzed theoretically. And then we milled the C/SiC composites by electroplating diamond cutting tool with different cutting parameters and fiber directions. The cutting force and the burr area size of the milling surface were also tested. After analyzing the results, the milling burr evaluation method was proposed. Then the burr area size of different fiber directions was analyzed, and the effect on the surface quality of fiber direction during milling process was studied. The result shows that the angle between surface laid carbon fiber direction and cutting direction has a significant influence on the processing quality. Milling surface quality was declined in order as 0°, 45°, 90° and 135°. So in order to improve the quality of the milling surface, the angle between surface laid fabric fiber direction and cutting direction should be less than 45°.

Abstract: Ultra-high-strength steel 30Cr3SiNiMoVA (30Cr3) which has excellent mechanical properties is usually used to manufacture the key parts in aviation industry. Precision hard milling is an efficiency way to machine 30Cr3 instead of grinding. Rounded cutting edge radius has important influence on the machining process due to small depth of cut. In order to better understanding the influence of rounded cutting edge radius, cutting forces, cutting temperature, critical depth of cut, etc., is analyzed by using finite element method (FEM). The results show that cutting forces in the y direction are more sensitively to the rounded cutting edge radii. Ploughing effect is also observed at the end of the climb milling process and it has significant influence on the quality of the machined surface. Simulation reveals that the increment of rounded cutting edge radius can lead to the increment of critical depth of cut correspondingly and the proportionality factor is about 14%.

Abstract: The orthogonal cutting tests of oxygen free copper with a cutting speed of from 1 m/s to 210 m/s were performed. The effect of the high-speed cutting on the improvement over the quality of the machined surface, which was evaluated by the thickness of the plastic flow layer and the surface roughness, was examined. By employing the simple shear plane model, the cutting mechanism was analyzed. The results were compared with the results for cutting of aluminum alloy obtained previously. For oxygen free copper, the resultant cutting force does not increase in high-speed cutting. However, the friction angle on the tool-chip interface rises clearly in high-speed cutting. This paper discusses the reason for the increase in the friction angle at the tool-chip interface by investigating the stress and temperature fields on the shear plane and the tool-chip interface.

Abstract: Based on orthogonal experiment of machining the irregular surface of Wulian red granite (G3768) with diamond profiling wheel, the relations between the fractal dimensions of cutting forces with machining parameters are studied. Cutting speed, feed speed and cutting depth are considered as the process parameters. The cutting force in machining granite operation are measured and the fractal dimension are calculated using using the algorithm of correlation dimension. From main effect plots the fractal dimensions of three directions of cutting forces are reduced with the increase of cutting speed and increased with the increase of feed speed and cutting depth. The mathematic models of fractal dimension of cutting force are developed by analysis of regression. The results of the ANOVA show that cutting speed and feed speed have remarkable influence to fractal dimension D_x, D_y and D_z.

Abstract: Grinding forces characteristics in elliptical ultrasonic assisted grinding (EUAG) of sapphire are investigated experimentally. The EUAG is a new grinding method proposed by the present authors in which an elliptical ultrasonic vibration is imposed on the workpiece by using an elliptical ultrasonic vibrator. In this paper, grinding experiments under the presence/absence of ultrasonic vibration assistance are performed. The effects of the vibration amplitude and grinding parameters such as the depth of cut, the grinding wheel speed on the grinding forces, grinding force ratio F_n/F_t are clarified. The obtained conclusions are as follows: the grinding forces during EUAG lowers to 50% and grinding forces ratio becomes reduced by 33% compared that during conventional grinding (CG); the grinding forces during EUAG have the less variation rate than those during CG as grinding parameters change; higher grinding wheel speed causes the larger grinding forces in CG, but has little effect on the variation of grinding forces in EUAG. By using EUAG method, the grinding forces and force ratio are greatly decreased, and surface quality is better, meaning that grindability of sapphire material is improved.

Abstract: Through turning experiment of machinable glass ceramics, the characteristics and law of turning force was studied. Results indicated that the overall changing process of cutting force was sinusoidal. If the cyclic fluctuation caused by system vibration was neglected, the changing process of turning force was scalariform. Through designing orthogonal experiment and applying numerical simulation of multiple regressing theory based on least square algorithm, mathematical model of turning force was established related with process parameters. R-test, F-test and P-test were carried out on the model respectively. The test results showed that the model had high precision. It could guide to cut machinable glass ceramics on prediction and controlling of turning force in some degree.

Abstract: In this paper, experiments are conducted to study the characters of Ultrasonic Assisted Grinding (UAG) and Conventional Grinding (CG), diamond grinding wheel is used in experiments, grinding forces and surface roughness are measured in both UAG and CG. The effects of different parameters on grinding force, surface roughness and force ratio are discussed. The results show that the grinding force and surface roughness in UAG is smaller than those in CG. The force ratio in UAG is lower than that in CG, which reveals that the grinding wheel has a good wear-resistant property in UAG process.