Infrared Thermography for Investigation of Surface Quality in Dry Finish Turning of Ti6Al4V

The machining of titanium alloys always raises issues because of their peculiar chemical and physical characteristics as compared to traditional steel or aluminum alloys. A proper selection of parameters and their monitoring during the cutting operation makes it possible to minimize the surface roughness and cutting force. In this experimental study, infrared thermography was used as a control parameter of the surface roughness of Ti6A4V in dry finish turning. An analysis of variance was carried out to determine the effect of the main cutting parameters (cutting speed and feed rate) on the surface roughness and cutting temperature. In the examined range of the machining parameters, cutting speed and feed were found to have a primary effect on the surface roughness of the machined parts. Cutting speed also significantly affected the temperature of the cutting region, while feed was of second order. Higher cutting speeds and intermediate feed values gave the best surface roughness. A regression analysis defined some models to relate the cutting temperature and surface roughness to the machining parameters. Infrared thermography demonstrated that the cutting temperature could be related to roughness.

Testing Tool Material on Scratch Tester

In manufacturing industry cutting tools are considered as the backbone of the metal cutting operation. In metal cutting operation there is relative motion between the tool and the workpiece. As the tool material is harder than the workpiece material, there is deformation of the workpiece which acts as a base for the formation of chips. If we observe the process of metal cutting, we can easily find out that there is a considerable amount of heat generated during the machining operation. As there is a point of interface between the tool and the workpiece, there is absorption of generated heat into both the tool as well as work material. Due to the absorption of the heat there is distortion in the tool material. In this research article we have taken the base parameters as speed, load and stroke and the output parameter is taken as the load which breaks the coating of the tool. Keywords: tool coating, scratch tester, speed, stroke, coating.

Optimization study of blasting operations in Roşia Poieni open pit mine, Romania

Purpose. Drilling-blasting technology is one of the simplest and most often used techniques in open pit mining. This allows the excavation of a large volume of rock and useful mineral substance. The operation of blasting using the energy of explosives plays an important role in open pit exploitation, being also the key element of the blasting process through which a corresponding granulometry is obtained. This operation is a part of a series of interdependent operations, in the sense that each operation determines a certain result that will be an important element for the next operation that takes place in the working face. Consequently, the blasting operation with explosives should not be considered as an independent act. A global approach to the entire production technological process including blasting is required. Methods. In the optimization study, the basic method consisted in the analysis of the blasting operations performed at the drilling diameter of 250 mm (blasting technology used in Roşia Poieni open pit mining) and simulation of the excavation of the same rock volume, with the optimization of the explosive charge distribution at two other drilling diameters: 200 and 150 mm. Findings. The main problems when shooting 250 mm dia holes are caused by the length of the tamping in the mineralized rock that leads to the appearance of blocks with dimensions which are maximum allowed in the crusher tank (1.2-1.3 m). That is why discontinuous loads with intermediate tamping are used – the method that successfully limits their number. In order to obtain a granulometry corresponding to the primary crushing operation, which will allow to decrease the crushing costs, it is necessary to use smaller drilling diameters, but with productivity high enough to ensure the optimal development of the extraction process. Originality. Based on the performed study, it is recommended to use the discontinuous load, preserving the total length of the explosive charge. In the zones where the rocks have a Protodiakonov coefficient f > 6.5, it is recommended to apply an appropriate drilling diameter (150-200 mm) and use the intermediate tamping at 2-3 m length to limit the upper stemming area to a maximum of 7 m (to limit or eliminate the occurrence of oversized blocks). Practical implications. The research results will enhance the geometric and safety factors of the operation, limiting the explosion effect on the massif and the environment and reducing the total costs of the cutting operation. The cost of explosives and initiating materials can be reduced by using a smaller quantity of explosive gels in a dry environment (12-18 kg/hole), the difference in the explosive charge length being completed with AM 1.

Failure mechanics analysis of AISI 4340 steel using finite element modeling of the milling process

A slot cutting operation is studied in this paper using a rotating/translating flat end milling insert. Milling operation usually comprises up-milling and down-milling processes. These two types of processes have different behaviors with opposite trends of the forces thus making the operation complex in nature. A detailed Finite Element (FE) model is proposed in this paper for the failure analysis of milling operation by incorporating damage initiation criterion followed by damage evolution mechanism. The FE model was validated with experimental results and good correlations were found between the two. The failure criteria field variable (JCCRT) was traced on the workpiece to observe the amount and rate of cutting during the machining process. It was found that the model was able to predict different failure energies that are dissipated during the machining operation which are finally shown to be balanced. It was also shown that the variation of these energies with the tool rotation angle was following the actual physical phenomenon that occurred during the cutting operation. Among all the energies, plastic dissipation energy was found to be the major contributor to the total energy of the system. A progressive failure analysis was further carried out to observe the nature of failure and the variation of stress components and temperature occurring during the machining process. The model proposed in this study will be useful for designers and engineers to plan their troubleshooting in various applications involving on-spot machining.

Flawless Cutting of Tubing and Control Lines by Mechanical Pipe Cutter in Challenging Well Condition Provides an Environmental Friendly Alternative: A Case Study from Brunei

The Electro-Mechanical Pipe Cutter (MPC) is a non-ballistic & non-chemical wireline deployed alternative cutter tool for parting downhole tubular in the process of well abandonment, pipe recovery and retrieving of packer elements. This case study showcases its application in two wells with different challenges in cutting 4.5" tubing viz., (i) with multiple control lines to facilitate fishing operations and (ii) under compression in a highly deviated trajectory. In Well A, Brunei offshore, the position of the tubing and orientation of the control lines were challenging for ballistic option, along with the possibility of scarring the 9-7/8" casing during the cutting operation. Thus, 3-1/8" OD MPC was used for this job to cut near the coupling, ensuring optimum stand off from casing wall aiming to achieve cutting the control lines in tension. Dual cut were designed to allow the room for a safe cut zone. The primary cut was performed near middle of the joint at ∼1985m, with the tubing in tension. The cut was initiated at a very slow feed (0.2 mm/min) and motor rates (4000rpm), which was gradually increased once the cutting was stable. After the accomplishment of the tubing cut, the parameters were again reduced to carefully cutting through control line. The tubing was successfully retrieved with smooth cut without any over pull indicating it to be completely free. The flawless cutting operation was performed in less than one hour with outmost efficiency. In another highly inclined Well B, Brunei offshore, MPC was chosen over ballistic because it was needed to be conveyed by tractor and ballistic shock has potential to damage it during the operation. Also the advantage of MPC to perform multiple cuts in one run, made it a preferred choice. In this well, multiple cuts were performed to weaken the joint connection of the tubing to allow the rig to pull it free. It was to overcome the adversity posed by high inclination and the pipe under compression. Three cuts were performed at ∼2996 m, each 20 cm apart with an OD of nearly 4.609". After completion of the job, the circulation was performed with surface return, indicating successful execution and the tubing was retrieved on surface showing a clean cut. This case study shows the appropriate planning and execution of the mechanical pipe cutter can provide an efficient, environment friendly and safe alternative to cut tubing and control line in the challenging condition especially when an explosive and chemical cutter options are not considered suitable.

Design of bamboo cutting mechanism based on crack propagation principle

Bamboo is mainly grown in hilly areas, and the harvesting of bamboo basically relies on labor. Moreover, the bamboo is prone to splitting problems during harvesting. To liberate labor and improve work efficiency, the crack propagation principle of bamboo was studied. Based on this study, a new cutting scheme using spiral feed was proposed. Additionally, a new bamboo cutting mechanism was designed. The new cutting mechanism, when installed on a harvesting vehicle, can automatically complete the cutting operation. The cutting mechanism is different from the traditional ones, and it uses four sets of saw blades for spiral feed cutting around the bamboo, which can reduce the splitting probability during the cutting process. Finally, a solid model of the cutting mechanism was built, and the basic movement process was simulated to verify the feasibility of the bamboo cutting mechanism.

A COMPREHENSIVE REVIEW ON EVALUATION OF ENVIRONMENTAL FRIENDLY MACHINABILITY, CUTTING FLUIDS AND TECHNIQUES IN METAL CUTTING OPERATION

Todays, due to the environmental concerns, growing contamination and pollution regulations, the demand for renewable and biodegradable cutting fluids is increasing day by day. Environmental friendly machining is one of the latest approach which is economical and also eco-friendly that improve the machinability. Different types of environmental friendly machining techniques are available e.g. MQL machining, cryogenic machining, dry machining and high pressure cooling approach. In this article, an attempt is made regarding environmental friendly machining processing, including different types of cutting fluids and machining techniques. The Knowledge of cutting fluid and its processing conditions is of critically importance to maximize the efficiency of cutting fluids in any machining process. In general, the generation of heat in the cutting zone due to friction at the tool-chip interface and the friction between the safety surface of the tool and the work piece is always the deciding factor on the quality of the work piece surface. In any manufacturing industries or company two factors play important role in machinability and productivity e.g. surface quality and tool wear. The main objective of this review article that analysis the different environmental friendly machining techniques and encourages the cooling approach in metal cutting operation. So finally, after the literature survey found that environmental friendly machining approach is cost effective machining process and also eco-friendly machining process.

Finite element modelling of the Taylor impact test in 3D with the Coupled Eulerian-Lagrangian method

When modelling a cutting operation, the constitutive model of the machined material is one of the key parameters to obtain accurate and realistic results. Up to now, the Johnson-Cook model is still the most used, even if an increasing number of models, such as the Hyperbolic TANgent (TANH) model, were introduced last years to overcome its limitations and come closer to the actual material behaviour. Experimental tests on dedicated equipment are usually required to identify the parameters of the constitutive models. This paper introduces the Coupled Eulerian-Lagrangian (CEL) formalism to model in 3D the Taylor impact test, one of the common tests to perform that parameters identification. Indeed, one identification way involves modelling the test to determine the constitutive model parameters by comparing the experimental and the numerical samples geometries. The developed CEL model is validated against a Lagrangian reference model for a steel alloy and the Johnson-Cook constitutive model. The main goal of using the CEL method is to get rid of the elements distortion due to the high strains and strain rates during the test. Mesh dependence of the results is highlighted and a recommendation is provided on the mesh to adopt for future work. The CEL model of the 3D Taylor impact test is then extended to the use of the TANH model. The results are finally compared with that of the Johnson-Cook constitutive model.

Structural dynamics of a 3 DOF parallel kinematic machine

Milling is an intrinsically interrupted cutting operation; therefore, vibrations occur. There are both self-excited (chatter) and forced vibration. Vibrations in milling appear due to the lack of dynamic stiffness of some components in the machine tool-tool-workpiece system. If the vibrations are excessive, the machine stability is negatively affected. In this paper a parallel kinematic machine is modelled and structurally analyzed, considering vibrational parameters (mass, inertia, stiffness, and damping). Theoretical results are used to verify the model. The proposed model provides an effective guide to design milling machines with the best structural arrangement (architecture) and enhancing performance. The value of this finding is in answering the research question: ""Should the machine tool-tool-workpiece system be kept decoupled to mitigate the vibration generated during a cutting operation?"". Two approaches were proposed to determine which option (coupled or decoupled bases) provides greater dynamic rigidity. The evidence shows that the decoupled base proposal maintains a cutting operation without displacement peaks due to greater operation times and better damping response.