EFFECT OF CUTTING PARAMETERS ON CUTTING FORCES IN TURNING OF CPM 10V STEEL

The objective of this paper is to investigate the effect of cutting parameters on cutting forces during turning of CPM 10V steel with coated cutting tool. Machining of CPM 10V steel and finding a suitable tool is very challenging due to its physical and mechanical properties, especially since the machining of this material has not been extensively researched. The experiments were carried out using an Index GU -600 CNC lathe and the cutting forces were measured in process. A three-factorial three-level experimental design was used for the experiments. Statistical method analysis of variance (ANOVA) is applied to study the effects of cutting speed, feed rate, and depth of cut on cutting forces. The results of this study show that depth of cut has the most significant effect on main force and radial force, while feed rate and cutting speed have the most significant effect on feed force. The developed model can be used in the machining industry to predict and analyze cutting parameters for optimal cutting forces.

Experimental Investigation and Optimization of Machining Parameters in Turning of Aluminum Alloy 075-T651

Aluminum alloy 7075-T651 is a widely used material in the aviation, marine, and automobile sectors. The wide application marks the importance of this material’s research in the manufacturing field. This research focuses on optimizing input process parameters of the turning process in the machining of Aluminum 7075-T651 with a tungsten carbide insert. The input machining parameters are cutting speed, feed, and depth of cut for the output response parameters cutting force, feed force, radial force, material removal, and surface roughness of the workpiece. For optimization of process parameters, the Taguchi method, with standard L9 orthogonal array, is used. ANOVA is applied to obtain signifi-cant factors and optimal combinations of process parameters.

Interaction between Thermal Modification Temperature of Spruce Wood and the Cutting and Fracture Parameters

This work examines the effect of thermal modification temperatures in the production of thermally modified wood on the cutting and fracture parameters when cutting heat-treated spruce wood by a circular sawblade machine. The samples were thermally modified at 160, 180, 200, and 220 °C. One sample was unmodified and was used as a reference sample. On the basis of the performed experiments, the fracture parameters (fracture toughness and shear yield strength) were calculated for the axial–perpendicular direction of cutting. In comparison with the theoretical assumptions, the influence of temperature on the cutting and fracture parameters was confirmed. Thermally treated wood is characterized by increased fragility and susceptibility to crack formation, as well as reduced density, bending strength, and shear strength. These properties significantly affect the size of the cutting force and feed force, as well as the fracture parameters. As the temperature increases, the values of these parameters decrease. The mentioned material characteristics could be useful for the optimization of the cutting process, as well as for the issue of energy consumption during the machining of heat-treated wood.

Experimental Verification of a Highly Simplified, Preliminary Machinability Test for Wood-Based Boards in the Case of Drilling

In contrast to metalworking there are no standardized or (at least) generally accepted, relative machinability tests for innovative or less known wood-based panels. The most reliable testing procedures are based on the use of a specialized, accurate system for measuring cutting forces and on conducting all tests in conditions that are similar to real industrial conditions (machine tool, cutting parameters etc.). However, the need for a more simplified testing procedure has often been voiced—not all scientists specializing in wood-based materials development have a machine tool comparable to one that can be found in a real furniture factory and piezoelectric force sensors at their unlimited disposal. To meet this need, the highly simplified, preliminary machinability test for wood-based boards in the case of drilling was developed and tried. The results of experimental research suggest that the simplified way of testing of relative machinability of wood-based boards (i.e., testing based on the photoelectric measurement of the time needed to make a 10 mm deep hole under constant feed force) can be a useful substitute of standard machinability testing procedure (based on accurate cutting forces measurements carried out in the standard industrial conditions). When verifying the simplified testing procedure, samples from each of the three basic groups of wood-based materials of substantially different internal structures (fiberboard, particleboard, and veneer boards) were tested. The relationship between significantly reliable and highly simplified machinability indexes turned out to be at a satisfactory level (R2 = 0.97 for particleboards and R2 = 0.95 for fiberboards or boards made of veneer or solid wood). The use of a simplified procedure can be especially pragmatic in case of any preliminary testing of innovative wood-based boards during the material development work.

Tool Wear Analysis during Ultrasonic Assisted Turning of Nimonic-90 under Dry and Wet Conditions

Nickel-based superalloys are widely used in the aerospace, automotive, marine and medical sectors, owing to their high mechanical strength and corrosion resistance. However, they exhibit poor machinability due to low thermal conductivity, high shear modulus, strain hardening, etc. Various modifications have been incorporated into existing machining techniques to address these issues. One such modification is the incorporation of ultrasonic assistance to turning operations. The assisted process is popularly known as ultrasonic assisted turning (UAT), and uses ultrasonic vibration to the processing zone to cut the material. The present article investigates the effect of ultrasonic vibration on coated carbide tool wear for machining Nimonic-90 under dry and wet conditions. UAT and conventional turning (CT) were performed at constant cutting speed, feed rate and depth of cut. The results show that the main wear mechanisms were abrasion, chipping, notch wear and adhesion of the built-up edge in both processes. However, by using a coolant, the formation of the built-up edge was reduced. CT and UAT under dry conditions showed an approximate reduction of 20% in the width of flank wear compared to CT and UAT under wet conditions. UAT showed approximate reductions of 6–20% in cutting force and 13–27% in feed force compared to the CT process. The chips formed during UAT were thinner, smoother and shorter than those formed during CT.

μRIGS – Ultra-light Micropositioning Robotics for Universal MRI Guided Interventions

Performing minimal invasive interventions under real-time image guidance proves problematic in a closed-bore magnetic resonance imaging scanner. To enable better usability in MRI guided interventions, robotic systems could be used for additional assistance. However, the integration of such devices into the clinical workflow relates to many technical challenges in order to increase precision of the procedure while ensuring the overall safety. In this work, an MR compatible, compact, ultra-light and remotely controllable micropositioning system called μRIGS is presented. The instrument positioning unit can be operated in a 5-DoF range within a working volume of 2100 cm3with an instrument feed of 120 mm. The kinematics are actuated with a combination of non-metallic Bowden cables and electric stepper motors from a safe distance inside the scanner room, while their control is initiated from the control room via a custom-fitted GUI. Thereby, the precision of the positioning reproducibility of the respective DoF can be achieved with a mean deviation of 0.12 °. Furthermore, a feed force of 14 N can be provided to puncture various soft tissue.

Analysis of initiation of instability zones of drilling string and intensification of drilling process at well boring by rotating an d rotating-bit methods

Instable operation of a drilling string can be caused by design flaws, unreasonably selected drilling modes, as well as specific features of the drilling by bit, fixed on a long flexible rod with initial irregularities. It was established that a drilling string under the influence of constant torque and longitudinal feed load is deformed along a screw line. It was shown that the source of the dynamic state initiation of a rotating drilling string is an alternative friction between rock and the instrument, as well as variation of potential energy of the drilling string at its twisting and untwisting. At the string twisting the potential anergy is accumulating, at the untwisting it is released. In this case the drilling sting length begins to increase and the work of feed force is imposed to this shifting resulting in the instrument beat over the rock. The torsion oscillating process causes longitudinal periodic shifting of the string end, which lead to joint longitudinal and bending oscillations of the whole drilling column. Systems of differential equations obtained describing the joint bending-longitudinal oscillations of a drilling string, caused by torsion vibrations, initiating at the contact of a drilling instrument with rock. Approximate solutions of the systems presented, which take place with the basic natural frequency of the torsion oscillations of a two-mass system instrument - string - rotator drive. In this case the amplitudes of the drilling string bending oscillations are associated with characteristics variation of the friction between the instrument and the rock as well as with the angular frequency of the drilling string rotation. Zones of dynamic instability at rotation of the deformed drilling string due to acting force factors, as well as initial irregularities and centrifugal forces revealed. It was shown that they are initiated at critical speeds of the drilling string rotation, which coincides with any natural frequency of the bending oscillations of the stave. To intensify the drilling process, recommendation elaborated for equipping the rotary drilling rig with an additional pneumatic hammer. A calculated diagram of a drilling string, equipped by an additional pneumatic hammer considered. Parameters of the hammer in terms of frequency and amplitude are matched with the translational speed of well drilling. The total longitudinal and transverse shifts can be obtained by superposition of self-exciting and induces shifts.

IN-PROCESS MEASUREMENT AND NUMERICAL DETERMINATION OF THE TEMPERATURE IN THE CONTACT ZONE DURING SINGLE LIP DEEP HOLE DRILLING

In this presented work, the main objective is the in-process measurement of the thermal as-is state near the drilling contact zone by means of a sensor-integrated tool for single lip deep hole drilling (SLD). Additionally, the mechanical quantities feed force and drilling torque are evaluated. The process monitoring is essential to optimize the surface quality as well as the subsurface properties such as hardness and residual stresses. These quantities are strongly dependent on the thermo-mechanical as-is state in the cutting zone and in the contact zone between the guide pads and the drill hole surface. This contribution gives a project overview including the development of a sensor-integrated single lip deep hole driller for the in-process temperature measurement, the integration of sensor systems in the tool as well as the experimental investigations on the temperature, the feed force and the drilling torque during drilling of a 42CrMo4 steel. The temperature measurement at eleven positions in the driller head provides data to observe the heat generation, distribution, and flow independently from the workpiece characteristics. However, one of the greatest benefits is the non-destructive fashion of the measurement system with their sensor integrated in the tool and thus the reusability. A simulation method, which uses the experimental results as a reference, is used to predict the thermo-mechanical conditions in the contact zone of the drill head and the workpiece. The results of these thermo-mechanical process simulations and the validation of this applied FE approach using the measured quantities are presented, too. The results of this work are part of an interdisciplinary research project in the framework of the priority program "Surface Conditioning in Machining Processes" (SPP 2086) of the German Research Foundation (DFG).

Effect of Increasing Spindle Speed at a Constant Chip Load on Cutting Force Behaviour of Hastelloy X

Cutting force is vital in machining nickel-based superalloys due to their excellent mechanical properties, thus creating difficulty in cutting. In the current scenario of metal machining, milling processes require high spindle speed and low chip load, which result in a low cutting force. However, low chip load not only result in low cutting force but also result in a low material removal rate (MRR). It is contrary to the ultimate high-speed machining (HSM) goal, which is to improve productivity and cost-effectiveness. Therefore, the emergence of an approach for achieving simultaneous low cutting force and high MRR is crucial. This paper presents the effect of increasing spindle speed at a constant chip load on the cutting force of Hastelloy X during half-immersion up-milling and half-immersion down-milling. In both half-immersions, the simulation results and experimental results are in good agreement. The percentage contribution of feed force, normal force and axial force to the resultant force can be arranged descendingly from high to low as axial force > normal force > axial force. Moreover, feed force, normal force, axial force and resultant force have a U-shaped behaviour. The spindle speed of 24,100 rpm and a chip load of 0.019 mm/tooth were found to achieve both low cutting force and high MRR.