Based on experimental results, performed on an instrumented single wire saw, an analytical model for the macroscopic mechanical conditions in the wire sawing process is presented. The model describes ...the influence of important process parameters like wire velocity, feed velocity and tension force as well as geometric relations like ingot size and wire length to the lapping pressure and the shape of the formed wire bow. The model is based on macroscopic, measurable, machining parameters and uses the experimentally determined relation between pressure and removal rate according to Prestons law. The derived equations are used to study the influence of typical process parameters systematically and the results are exemplified for the production line of 6
in solar wafers.
► An analytical model for the macroscopic mechanical conditions in the wire sawing process is presented. ► The influence of important process parameters as well as geometric relations are considered. ► Experimental studies, performed on an instrumented single wire saw, are presented. ► The experimental results are in good agreement with the analytical model. ► The influence of important wire sawing parameters is studied.
The main objective of this work is to analyse the problem of determining the boundary of elastoplastic zone with various methods of machining parts by cutting. The structure of complex theoretical ...and experimental studies of energy–power parameters of the technological processes is considered. The method for calculating the processes of plastic deformation of metals based on a closed set of equations of continuum mechanics is proposed for the theoretical study of energy–power parameters of the technological processes. The expressions, which make possible the reproduction of the spatial pattern of the strain distribution within the metal at the diamond smoothing and grinding, are obtained. This allows visualizing the mechanism of the deformation and simplifying the analysis of the deformed state of the material. Functional relationship between the power of the deformation and parameters of the machining conditions at the diamond smoothing and grinding is established. Various methods for determining the cutting forces during machining with chip removal as well as approaches to determining deflected mode of a material are considered. A method for express calculation of cutting forces using well-known engineering techniques is proposed. The experimental and calculated data on determination of the sizes of plastically deformable zone of difficult-to-cut materials are analysed. The mechanism of inhibition of dislocations and energy conversion during deformation is considered in detail. As a result, a dislocation–kinetic approach is developed, based on the concept of dislocation as a quasi-particle of a strain quantum. Using the dislocation–kinetic approach, the mathematical model is developed, which allows us to calculate a magnitude of the zone of leading cold hardening that is confirmed by comparison with experimental data. The Starkov’s model is improved; the physical meaning of coefficient in formulas for calculating boundaries of cold-hardening zones is explained. A new similarity criterion is introduced, which relates dissipation of plastic strain energy and rate of rearranging of temperature field.
The severe abrasive wear of the current cemented tungsten carbide (WC) tools is a "bottleneck" that limits the usage of machinery in hard rock mines. To address this issue, a revolutionary thermally ...stable diamond composite (TSDC) based cutting tool, also called Super Material Abrasive Resistant Tool (SMART*CUT) was developed by CSIRO. Before this novel tool is employed for practical rock cutting, the effects of the cutting parameters on the performance of the SMART*CUT picks must be determined and the cutting forces of the picks have to be estimated as they directly affect the capability and efficiency of the selected cutterhead and hence the excavation machine. In this study, rock cutting tests based on Taguchi's L25 orthogonal array were conducted to analyze the cutting parameters. The signal-to-noise (S/N) ratios and the analysis of variance (ANOVA) were applied to investigate the effects of depth of cut, attack angle, spacing and cutting speed on mean cutting and normal forces during the rock cutting process. Empirical models for predicting the cutting forces on SMART*CUT picks were developed using multiple linear regression (MLR) and artificial neural network (ANN) techniques. Parametric combinations for minimizing the cutting forces and the statistical significance of process factors were successfully determined by using the Taguchi technique. Good prediction capabilities with acceptable errors were achieved by the developed MLR and ANN models. However, the ANN models offered better accuracy and less deviation.
Energy and time savings are highly important aspects of green manufacturing. Ultrasonic vibration-assisted grinding (UVAG) is a high-efficiency, low-energy-consumption processing method for optical ...components made from hard and brittle materials. This work presents an experimental investigation of the specific grinding energy and the subsurface damage depth in UVAG of optical glasses to estimate the increased energy and time savings produced when using UVAG in optical glass manufacturing. The normal and tangential grinding forces of traditional grinding (TG) and axial UVAG processes on optical glasses were investigated for various machining parameters. The specific grinding energies during the TG and UVAG of the optical glasses were calculated and analyzed from the perspective of the energy consumption of the grinding process. The subsurface damage depths in optical glass during TG and UVAG were measured as an estimate of the machining quality, and the magnetorheological polishing spot method was used to analyze the time saved in subsequent polishing processes. The results show that UVAG can reduce energy consumption during the grinding of glass and produce significant time savings in subsequent polishing processes. The UVAG process therefore shows good potential for use in green manufacturing of optical components.
Determination of the ploughing forces is necessary for monitoring the wear of the cutting tool in micro cutting. The aim of this research was to increase the accuracy of determining the ploughing ...force and the determination of the influence of the uncut chip thickness on the ploughing force. A new method for determining the ploughing forces is suggested in this article. It was found that the ploughing forces determined by the new method were greater than those determined by the method comparing total forces at different flank levels of wear. It was first established that the uncut chip thickness influences the ploughing force.
The subject of this experiment was to produce parts with a specific shape and submillimetre elements. The parts represented components of commercial sparkplugs and the machined section was made of ...almost pure nickel. Relatively narrow required tolerance of parts (hundreds of micrometres), in combination with a large addition of material to the semi-finished product (several millimetres) and the required number of parts manufactured by one cutting insert for a very small time cycle led to the implementation of several tests to find ideal cutting inserts and conditions for production. All of the machining was done under dry conditions and the lowest possible machining time was also taken into account. Seven inserts with potentially suitable cutting-edge geometries were selected for testing. They were positive ISO C and ISO D inserts. After initial testing and determining the most suitable conditions for the most inserts, cutting forces during machining under constant conditions were measured. After the machining, each part was closely inspected by the microscope and all the critical dimensions, general shape and state of the surface were evaluated. In the course of the experiment, a significant effect of the geometry of the cutting insert was demonstrated. The best performing of used cutting inserts for these conditions was ISO D shape with a nose radius of 0.2 mm and a highly positive rake angle. In terms of the thin layer used, a TiAlN PVD coated insert seems to be the most ideal as it should significantly increase tool life. To verify this assumption extensive long-term testing would have to be done. These results confirm the importance of selecting appropriately positive geometry for turning small features in soft alloys along with the influence of nose radius with regard to depth of cut. Keywords: Cutting forces; nickel; turning; cutting tool geometry
Machining of carbon fibre reinforced polymers is an important step for the integration of advanced materials into engineering applications. Machining damage due to excessive cutting forces may cause ...the rejection of the composite components at the final stages of their production cycle. The cutting forces are related to the surface finish and tool wear. This latter affects also the cost of processing.
This paper analyses the diamond electroplated tools milling of carbon fibre reinforced polymers and a comparison with the milling by tools with inserts is presented. In literature, the milling of carbon fibre reinforced polymers with diamond electroplated tools is little explored but it is very interesting in the phase of machining and post-machining of structural parts with complex geometry.
The analysis of the cutting forces, tool wear and surface finishing in relation to the main process parameters was carried out. A decrease of the cutting forces, of the surface roughness and of tool life was noticed passing from the tool with inserts to the diamond electroplated one.
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•The milling of CFRP with diamond electroplated tools is very interesting in the phase of machining of structural parts.•This paper analyses the diamond tools milling of CFRP and a comparison with the milling by tools with inserts is presented.•The comparison has been made by considering the process forces and the tool wear as a function of the main process parameters.•The work shows the innovative and potential for milling of composite materials.
Surgical procedures that affect the human body's bone structure, often entail cutting, drilling or screwing operations of bone. The post-operative success of these procedures is largely dependent on ...the degree of damage introduced by the process. In this article, the influence of the rotational velocity, feed per tooth and two drill bit type on workpiece temperatures and cutting forces when drilling bovine cortical bone has been studied. The purpose is to find the optimum cutting conditions that will generate the lower temperatures and cutting forces. The measurement of temperatures has been carried out with an infrared thermography camera, and a piezoelectric dynamometer has been employed to obtain forces. A model has been developed from which heat flow into the drilled bone can be estimated from specific cutting force and the fraction of total heat generated that flows into the bone. This fraction has been shown to depend on the Peclet number for the process, proportional to the drill rotation speed, the feed per cutting edge and the diameter of the drill. By means of the model, some contradictions in the literature as to the effect on bone heating of increasing rotation speeds and feeds per cutting edge have been resolved.
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