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A new experimental approach to identify, the cutting dynamics in turning operations is presented. This method treats the problem as a closed-loop gray-box identification problem and is based upon spectral analysis and least squares estimation techniques. An active magnetic bearing is employed both to excite the system and to increase the tool's damping. The inherent time delay of the cutting process is 'removed' in identification by limiting the observation period to less than one revolution period of the workpiece. The coefficients of several cutting tests were identified. The methodology was validated by predicting the critical depth of cut from the identification results and comparing with the experiment result measured from a cutting test. [DOI: 10.1115/1.2034509]

Abstract: This study discussed the development of the first and second order power prediction model for milling 618 stainless steel with coated carbides cutting tool. The first and second order [...]

In intelligent machine tools, a computer based control system, which can adapt the machining parameters in an optimal fashion based on sensor measurements of the machining process, should be incorporated. In this paper, the method for adaptive optimization of the cutting conditions in a face milling operation for maximizing the material removal rate is proposed. The optimization procedure described uses an exterior penalty function method in conjunction with a multilayered neural network. Two neural networks are introduced: one for estimating tool wear length, and the other for mapping input and output relations from the experimental data during cutting. The adaptive optimization of the cutting conditions is then implemented using the tool wear information and predicted process output. The results are demonstrated with respect to each level of machining such as rough, fine, and finish cutting.

An enhanced model for the prediction of static cutting forces in face milling is presented. The key features of the model include the ability to handle complex workpiece geometry, two-dimensional cutter feed paths, multiple pass machining, and effects of machine set-up errors. A two-dimensional boundary representation scheme is used to describe the workpiece geometry which may contain holes, slots, and other complex geometrical features. Variable cutter feed paths are represented by a combination of linear and circular arcs. In view of this and the complex workpiece geometry, a new algorithm for cutter-workpiece engagement determination is developed. Several sources of machine set-up error such as spindle and cutter axis tilt, and cutter center offset runout are modeled and their individual as well as combined effects on key machining process variables such as the axial and the radial depth of cut illustrated. Results of model verification experiments are reported for different workpiece geometry and cutter feed paths. A comparison of the predicted and measured forces shows good agreement.

In-plane stress distribution in a spinning free-clamped slicing blade is studied analytically. The blade is subjected to a stationary, distributed, in-plane slicing load along the inner periphery, while it is clamped and tensioned initially in the radial direction along the outer boundary. The radial, hoop, and shear stresses in the blade are given by sum of the stresses from the tensioning, spinning, and edge loading. The solution is obtained by introducing the Lame potential functions and the two- dimensional elasticity theory. Numerical results are presented for an actual SUS301 blade cutting a 6-in.-diameter silicon ingot at 1550 rpm. Results obtained show that the contribution of the slicing load on the stress distribution is not significant; further the overall stress distribution is approximated by that of the initial tensioning except for the case of the shear stress distribution.

Byline: Daniel Iliescu, Daniel Gehin, Mohammed Nouari, Franck Girot Damage mechanisms of tipped tungsten carbide tools have been investigated when dry machining of multi-directional carbon fibre composites. The objective of this study is to determine the effects of the cutting parameters on the tool-workpiece interface and to identify the different wear modes. Different rake angles (0, 15 and 30), and feed rates (0.05, 0.1 and 0.2 mm/rev) were tested for a constant cutting speed (60 m/min). The cutting loads were determined, and the tool surface topography was analysed using complementary techniques. All aspects of material removal were found to be primarily dependent on the fibre orientation.

Byline: M.B. Cai, X.P. Li, M. Rahman Unlike in conventional cutting processes, where the undeformed chip thickness is significant compared to the cutting tool edge radius, in nanoscale cutting processes, the undeformed chip thickness is very small, on the nanoscales. Therefore, the tool edge radius can not been ignored. It has been found that there is a brittle-ductile transition in cutting of brittle materials when the cutting tool edge radius is reduced to nanoscale and the undeformed chip thickness is smaller than the tool edge radius. In order to better understand the mechanism of the transition, a molecular dynamics (MD) method, which is different from continuous linear mechanics, is employed to model and simulate the nanoscale ductile mode cutting process of monocrystalline silicon wafer. The simulated variation of the cutting forces with the tool cutting edge radius is compared with the results of the cutting force from experimental cutting tests and they show a good agreement. In the simulated results, it can be seen that the thrust force is much larger than the cutting force in cutting. The simulated results also denote that the resultant force in the cutting process is not uniformly distributed along the cutting tool edge. In the simulation, the elastic springback of small thickness is observed on the machined workpiece surface.

Byline: N. Geren, M. Bayramoglu, T. Tunc The water jet machine (WJM) tool is quickly gaining industrial acceptance for cutting nearly all types of materials into complex shapes. However, the high cost of these systems restricts their use by small and medium scale industries. The intensifier is the key unit of the WJM and significantly affects the cost of a WJM. Therefore, the present work aims to develop an intensifier for a low-cost WJM by applying reverse engineering and redesign methodology. The paper particularly concentrates on the design of high pressure components which require shrink-fitted assembly. The use of redesign technique together with the equations derived for this work have simplified the design of shrink-fitted parts and helped to minimise the time taken for the design of WJM intensifier. The design procedure used in this work not only simplifies the design, but also eliminates the re-machining requirement which is generally required to bring the inner radius of the intensifier to its desired size after the shrink-fit.