Tool Nose Research Articles

Interactive coupling of structural dynamics and milling forces for high-frequency stability prediction in robotic milling

Robotic machining has developed rapidly and has great potential for manufacturing large parts with complex surfaces. However, the machining quality and efficiency are severely limited by the low stiffness of the robots, which causes destructive chatter during manufacturing. To suppress this phenomenon, offline stability prediction must be performed before the actual robotic milling. In this study, a high-frequency stability prediction algorithm for robotic milling was developed by introducing an interactive method. A lightweight structural dynamic model of a robot was developed based on specially designed decoupling criteria, and an interpolation algorithm that determines the trajectory of the tool nose was designed to calculate the milling force. By combining the two models, an interactive coupling algorithm was proposed to forecast the vibration in robotic milling. The predicted results can contribute to generating the stability lobe, thereby verifying the stability distribution and spectral characteristics of both the simulated and measured signals. The new algorithm realizes static data communication and dynamic state updating between the dynamic and cutting force models at high frequencies, thereby balancing the simulation speed and prediction quality.

Cutting performance and failure mechanisms of TiB2-TiC-Al2O3 multi-dimensional gradient ceramic tool in intermittent turning of hardened steel

The TiB2-TiC-Al2O3 multi-dimensional gradient ceramic tool (MDGCT), whose composition varied in two directions, were designed and fabricated via hot-pressed vacuum sintering. The cutting performance, including cutting force, cutting temperature and chip morphology, and failure mechanisms of MDGCT with different orientation angles in intermittent turning of SKD11 hardened steel were investigated in comparison with the homogeneous commercial ceramic tool CC650 at different depths of cut and cutting speeds. And the distribution of thermal residual stress of MDGCT was investigated employing FEM analysis. Results showed that the multi-dimensional gradient ceramic tool with orientation angle of 15 degree (TT3A15) had the optimal comprehensive cutting performance. The main failure mechanisms of CC650 tool were chipping and fracture caused by crack propagation, while the crack propagation was effectively inhibited in the TT3A15 tool, and its failure mechanism was chipping at the tool nose. The contribution of multi-dimensional gradient structure of TT3A15 tool to the increasing residual compressive stress of minor cutting edge, the favorable anti-crack capacity of flank face and the heterogeneity of physical and mechanical properties of rake face were responsible for its optimal cutting performance.

Influence of cutting parameters and tool nose radius on the wear behavior of coated carbide tool when turning austenitic stainless steel

This study investigated the wear behavior of coated carbide tool with different tool nose radius under different cutting parameters when turning AISI 321 austenitic stainless steel. The full factorial turning experiments with three factors and two levels cutting parameters were carried out. The wear progression of the tool with cutting time was recorded. The tool wear mechanism and the influence of cutting parameters and tool nose radius on the tool wear behavior were analyzed. The results showed that the cutting tool mainly exhibited wear manners of abrasive wear, adhesive wear, and oxidation wear. The tool life varies a lot with the cutting parameters, with the feed rate the most sensitive. Decrease the nose radius makes the strength of the tool blade worsened, thereby increasing the tool life sensitivity to cutting parameters. However, decreasing the tool nose radius can effectively increase the tool life. The reason is that when the tool nose radius is reduced, the cutting temperature can be decreased and at the same time the chip breaking performance can be improved, which decrease the mechanical damage of chips to the tool and related wear, and thus resulting in a longer tool life.

The structure design and cutting performance research about the groove of the indexable inserts for machining stainless steel

Stainless steel is a notoriously difficult-to-machine material, with challenges such as hard-to-break chips and severe tool wear. To address these issues, a finishing indexable insert has been designed and developed specifically for stainless steel. This tool, named HMF, was compared to commercial tools (NF4, BF) in terms of its curved groove structure and cutting performance using SEM (scanning electron microscope Sigma500), 3D scanning (KEYENCE-VR 5000) and a profiler (Mitutoyo C-200). The HMF tool utilizes a curved edge with a curved chip breaker, and a chip-breaking bump on the tool nose. The groove parameters of the HMF insert are as follows: cutting edge angle of 12°, chip breaker groove width of 1.89 mm, back wall height of 0.095 mm, and anti-chip angle of 4°49’. 3D scanning of the chip break site reveals that the HMF chip break has a higher bump and a more pronounced chip rolling effect. HMF tool chip-breaking experiments show that it has ideal chip-breaking performance in the finishing range of ap = 0.6–1.0 mm, and f = 0.1–0.25 mm r−1. Chip analysis shows that the HMF chip curl frequency increases and the chip curl is tighter as the feed rate increases, and the curl radius gradually decreases when the feed rate is greater than 0.15 mm r−1. The results of the wear performance study are as follows: all three tools show rake face crater wear when cutting stainless steel. A small amount of built-up edge appears on the HMF cutting edge. The wear life of HMF is close to NF4 and better than BF; the wear of BF is faster in the later stages of wear.

Long Sump Life Effects of a Naturally Aged Bio-Ester Oil Emulsion on Tool Wear in Finish Turning a Ni-Based Superalloy

This paper discusses a method of finish turning Inconel 718 alloy to compare machining performance of a naturally aged and used metalworking fluid (MWF), which had been conventionally managed through its life cycle, with the same new unaged product. The MWF concentrate was a new-to-market bio-ester oil, diluted with water to produce an emulsion. In the experiments, 50 mm diameter bars were turned down with multiple passes at a 250 μm depth of cut to reach a tool flank wear of 200 μm. The machining was interrupted at several stages to measure the flank wear and compare the chip forms for the aged and unaged MWF. The method of finish turning used a small tool nose radius and a small depth of cut that was found to be sensitive in detecting a difference in the flank wear and chip forms for the aged and unaged MWF. On the chemistry, the findings suggest that higher total hardness of the aged MWF was the cause of reduced lubricity and accelerated flank wear. This paper discusses the state of the art with the insights that underpin the finish turning method for the machinability assessment of MWFs. The findings point to stabilization of the MWF chemistry to maintain machining process capability over an extended sump life.

Experimental Analysis of Machining Parameters In Turning of Aluminum 7075

High-Speed Machining (HSM) of aluminum alloys represents a critical area in manufacturing industries, including automotive, aerospace and consumer electronics. This research presents an in-depth investigation into the effects of key process parameters on the HSM of Aluminum 7075, a high-strength alloy with superior mechanical properties. Utilizing the central composite design of Response Surface Methodology (RSM), the study scrutinizes the impact of process parameters, including cutting speed, feed, depth of cut and tool nose radius on surface roughness. The findings reveal feed and nose radius as primary factors influencing surface roughness while cutting speed and depth of cut play secondary roles. This comprehensive analysis contributes to the knowledge base for efficient machining practices and lays the groundwork for future optimization strategies. It also underscores the necessity for further research into understanding the intricate dynamics of machining parameters to enhance operational efficiency and product quality in the machining of Aluminum 7075 and similar alloys.

Grey Relational Analysis-based Interactions of Machining Parameters for Optimal Process Response: An Experimental Initiative

This study, investigated the optimal combining of tool nose radius and cutting variables for the overall performance for both AISI 4140 steel and IS-2062 steel. The both materials were machined on a centre lathe and measurements were taken. The data collected was analysed through grey relational analysis. Results showed that grey relational optimal interactions of machining parameters for the overall performance were: N R (0.35mm), U o (0.5mm), V w (65m/min), R f (0.2mm/rev) for both materials. Also, grey relational grade improved by 1.2767 (24.69%) for the expected optimal design for AISI-4140 steel, and improved by 1.7417 (33.68%) for the expected optimal design for IS-2062 steel. The expected responses were: cutting power 11.157 kW, specific metal removal rate 9.710 mm3/min.kW, cutting force 173.110 N, thrust force 77.207 N, shear force 124.838 N, surface roughness 5.00 , and Shear work 7945.9kNm/min for AISI-4140 steel; and cutting power 5.544 kW, specific metal removal rate 19.541 mm3/min.kW, cutting force 86.074 N, thrust force 39.440 N, shear force 65.688 N, surface roughness 6.165 , and shear work 4158.67 KNm/min for IS-2062 steel. Grey relational analysis reduced the factors affecting on the dependent variables to feed rate and depth of cut.

Finite element analysis and structure optimization of a gantry-type high-precision machine tool

The high-precision machine tool’s dynamic, static, and rigid nature directly affects the machining efficiency and surface quality. Static and dynamic analyses are essential for the design and improvement of precision machine to ensure good tool performance under difficult and demanding machining conditions. In this study, the performance of a high-precision machine tool was analyzed using its virtual model created using CAD. Static and model analysis using ANSYS Workbench software was conducted to establish the tool's static deformation and static stiffness. Furthermore, the static and dynamic characteristics of the tool were explored using a finite element modeling approach to study their performance. In particular, the structure, static force, modal, frequency spectrum, and topology optimization of machine tools were primarily analyzed. Using model analysis, we found the first four different frequencies (22.5, 28.9, 40.6, and 47.4 Hz) and vibration type, which suggested of a weak link. Further static structural analysis revealed that the deformation of the spindle was 67.26 μm. An experimental static rigidity analysis was performed, and the experimental deformation values of the tool and spindle were obtained. The static and dynamic characteristics, as well as the accuracy and efficiency of the finite element model, were verified by comparing the data with the finite element analysis (FEA) results. Subsequently, we modified the settings and analysis model to ensure that the analysis results were consistent with the experimental findings. The error between the two results was within 1.56%. For an applied load of 5000 N on the spindle nose, the tool nose transient response was 0.5 s based on transient analysis. Under the condition that the structural deformation is as constant as possible, the lightweight structure may achieve the minimum weight and enhance the natural frequency; thus, the ideal structure will be obtained, and finite element analysis will then be performed. The optimal conditions for topology optimization include a lightweight structure, reduced structural deformation, and increased natural frequency of the structure. The developed method improves structural optimization, increases the ability of the product to be manufactured, and offers designers a variety of price-effective options.

Investigating the machinability behaviour of Al7075/SiC5CS5 hybrid composite with the variation of tool geometry

This research investigates the machinability behavior of an Al7075 hybrid composite fabricated with micro-sized cenosphere (CS) and silicon carbide (SiC) particles. The composite was fabricated using stir-casting with ultrasonic assistance. The experimental study investigated the effect of variation of machining regimes (i.e., feed rate, cutting speed, and depth of cut) and tool geometry (tool nose radii) on main cutting force and tool tip temperature. For the study, the Cermet tool was considered as tool material for the dry turning of aluminum alloy and composite. In addition, a regression model was created using the response surface method (RSM) technique. The results indicate that the developed model can accurately predict output regimes with an accuracy ranging from 80.44 to 99.98%. Further, by using sequential approximation optimization, the optimal combination of input regimes for maximal metal removal rate was identified.

Determination of Cutting Tool Performance Characteristics in Machining Nickel Based Super Alloys

Cutting tool materials often undergo severe mechanical stresses and thermal changes when machining nickel-based superalloys. The stresses and temperatures that arise when machining nickel-based superalloys greatly increase the blunting and wear rate of the cutting tool. As a result, tool life is adversely affected. It is seen from important studies that adhesion and abrasion wear mechanisms are more dominant in the processing of Inconel 718. The work material adheres to the cutting edge, forming a BUE. Depending on the cutting conditions, stable BUE is not always formed and this layer is sometimes repeatedly removed with the chips. Notching in the depth of cut, wear on the tool nose and coating layer is caused by the presence of hard particles in Inconel 718 and causes severe flank wear. Flank wear and notch are the main factors limiting tool life, and oxidation and diffusion occur as a result of high temperatures.

Analytical prediction of chip flow direction in cylindrical turning considering rounded edge effect

The flow direction of a no-free chip has a vital influence on chip control and the machined surface's integrity. In order to establish an accurate prediction model of chip flow direction, a new analytical model considering the effect of workpiece materials and tool nose radius on chip flow direction is proposed for cylindrical turning. The rounded edge engaged in cutting is segmented into many oblique cutting units to consider the effect of the nose radius on the chip flow, whose thermomechanical process of chip formation is characterized by the unequal division shear zone method. The mutual action forces of each discrete chip are calculated to determine the resultant chip flow direction, and the interaction between the constrained chip units is comprehensively considered as non-free chip flow. Simultaneously, the influences of material constitutive and cutting parameters on the flow direction of discrete chip and resultant chip are analyzed by thermomechanical coupling method. The conducted mechanism of the nose radius and the main cutting edge angle on unconstrained and constrained chips is studied. The predicted results of chip flow direction were validated with experimental values and Colewell's model, and the FE simulation was also used to compare with the proposed model, interesting agreement was found.

Statistical analysis, modeling and multi-objective optimization of parameters intermittent turning process of AISI D3

Intermittent machining is characterized by its complex and irregular context. This intermittency causes machining to occur under difficult conditions that greatly influence the technological performance parameters. The aim of the present work is to evaluate the effects of input parameters, cutting speed, Vc, depth of cut, ap, tool nose radius, r and feed rate, f, on surface roughness, Ra, tangential cutting force, Fz, motor power consumption, Pm, cutting power, Pc and material removal rate (MRR), during intermittent turning (IT) of AISI D3 tool steel. Machining was performed with a triple CVD coated carbide tool (AI2O3/TiC/TiCN) by adopting a Taguchi L9 (3^4) experimental design. The ANOVA and RSM methods were used to analyze the effects of cutting factors on the outputs parameters resulting in statistical prediction models. In addition, a multi-objective optimization of the cutting conditions exploiting the desirability function (DF) was done according to four cases of relative importance corresponding to different industrial contexts. Furthermore, the grey relational analysis (GRA) method was applied and compared with the DF method. The results show that the optimal regime found by the DF method, (r =1.6mm, Vc= 240 m/min, f = 0.084 mm/rev and ap = 0.64 mm), favors Ra and MRR. On the other hand, for the GRA method, the combination of (r = 0.4 mm, Vc = 240 m/min f = 0.08 mm/rev and ap = 0.3 mm) favors the minimization of Fz, Pm and Pc. This work presents an originality because the results found are very useful in the field of optimization for a better control of the process IT.

Investigation on surface quality in micro milling of additive manufactured Ti6Al4V titanium alloy

The additive manufactured technology is widely applied to produce titanium alloy parts with complex structures. The subsequent machining operations are necessary for additive manufactured parts to achieve the required machining quality. In this paper, the theoretical surface roughness model in micro milling was established. The model indicated the theoretical milled roughness mainly depends on the feed per tooth, tool nose radius and bottom edge inclination angle. Then, micro milling experiments are conducted on additive manufactured titanium alloy using PCD micro end mill. The surface roughness on milled surface was measured and investigated. At the middle position of micro milled surface, the distribution curves of surface roughness Ra and Sa show the same variation trend under different milling parameters. Moreover, the measured surface roughness results on different transverse positions of milled surface showed that the difference value between the actual and theoretical surface roughness of milled surface is mostly induced by the unstable cutting behaviors, which is also mainly responsible for the surface roughness size effect. The transverse distribution of surface roughness on milled surface exhibited a W shape because of the variation of the instantaneous undeformed chip thickness and material removal mode at different transverse positions.

Investigation and Statistical Analysis for Optimizing Surface Roughness, Cutting Forces, Temperature, and Productivity in Turning Grey Cast Iron

This paper investigated the influence of cutting parameters, including feed rate, cutting speed, tool nose radius, and wet or dry cutting conditions, on the resultant force, cutting edge/workpiece temperature, and surface roughness when turning grey cast iron. Results showed that increasing the feed rate increased the resultant force, cutting temperature, and surface roughness. At the same time, increasing the cutting speed and nose radius increased the cutting temperature, which in turn reduced the resultant force. For practical applications, basic mathematical calculations based on the sole effect of each parameter on the output of the experiments were used to estimate the extent of percentage increase in cutting temperature due to increasing feed rate, cutting speed, and nose radius. Similarly, the same approach was used to estimate the effect of increasing feed rate, cutting speed, and nose radius on average surface roughness. Results showed that increasing the feed rate increases the cutting temperature by 5 to 11% depending on the nose radius and cutting speed. On the other hand, increasing the cutting speed was found to have limited effect on cutting temperature with small nose radius whereas this effect increases with increasing the nose radius reaching about 11%. Increasing the nose radius also increases the cutting temperature, depending mainly on cutting speed, reaching a maximum of 21% at higher cutting speeds. Results also showed that increasing the feed rate increased the average surface roughness considerably to about 120% at high cutting speeds and a large nose radius. On the other hand, increasing the cutting speed and nose radius reduced the surface roughness (i.e., improved surface quality) by a maximum of 29 and 23%, respectively. In order to study the combined effects of the cutting parameters on the three responses, namely, the resultant cutting force, cutting temperature, and surface roughness, full factorial design and ANOVA were used, where it was found to be in good agreement with mathematical calculations. Additionally, the desirability function optimization tool was used to minimize the measured responses whilst maximizing the material removal rate.

Multi-objective optimization of tool nose radius and machining conditions employing Taguchi-based grey relational analysis in milling of AISI 304

Multi-objective optimization of tool nose radius and machining conditions employing Taguchi-based grey relational analysis in milling of AISI 304

The effect of chip formation on the cutting force and tool wear in high-speed milling Inconel 718

Coated carbide tools are widely used in the processing of nickel-based superalloys due to their excellent wear resistance, high strength, and good hardness at high temperatures. In this paper, the high-speed milling experiments and finite element simulation of Inconel 718 are carried out by using PVD TiAlN-coated carbide tools. Simulations of tool temperature, cutting force, and chip morphology were performed to analyze the effect of cutting speed on the degree of sawtooth chip formation and the effect of sawtooth chip formation on the cutting force and tool wear. The results show that the cutting temperature mainly focuses on the rake face, and with the cutting speed increasing from 60 to 120 m/min, the maximum temperature of the rake face increases from 580 to 660 ℃. The maximum temperature region (MTR) on the rake face gradually approaches the tool nose with a decrease in the cutting speed. The generation of sawtooth chips leads to fluctuations in the cutting force component. As the cutting speed increases, the degree of chip sawing increases. The effect of the sawtooth chip on the fluctuation of the cutting force will also increase, thus increasing the degree of tool wear.

Multi-Objective Optimization of Turning Process by Fuca Method

Abstract A study about multi-objective optimization of turning process has been done in this paper. Twenty-five experiments of a matrix designed according to Taguchi method have been performed. In each experiment, the values of five parameters were changed, including tool nose radius, tool holder length, spindle speed, feed rate, and cutting depth. The three output parameters determined for each experiment include surface roughness, roundness deviation and material removal capacity. Four different methods were used to calculate the weights of the output parameters. The FUCA method was used to solve the multi-objective optimization problem. This work was repeated four times with four corresponding weight sets of the criteria. The purpose of solving the multi-objective optimization problem is determining the values of the input parameters to ensure both the surface roughness parameter and the roundness deviation parameter are the smaller the better, and the material removal capacity is the larger the better. A surprising thing happened, the optimal values of the set of input parameters were exactly the same when using four different weighting methods. Accordingly, the optimal values of tool nose radius, tool holder length, spindle speed, feed rate and cutting depth correspondingly are 0.8 (mm), 40 (mm), 587 (rev/min), 0.316 (mm/rev) and 0.6 (mm).

Application of Taguchi’s Orthogonal Array and S/N Ratio on Surface Roughness Optimization

Surface finish plays an important role in making quality products in the manufacturing sector. A turning experiment is conducted by cutting tool of nose radii (1 mm and 0.65 mm) to find its influence on surface roughness. Eight experiments were performed with Taguchi’s Orthogonal Array (OA) technique. The prime objective was to investigate the tool nose radius effects in the prediction of the optimum value of surface roughness. Cutting speed (V), feed (F), depth of cut (D), and tool nose radius (NR) were selected for the experimental work having two levels each. To find out the influential parameters analysis of variance (ANOVA) was carried out. Signal to noise ratio and average performance graph was analyzed to obtain optimum response values. The results concluded that the large nose radius develops a superior finish in comparison to the smaller one.

Research on three-dimensional ultrasonic vibration-assisted turning cutting force

Three-dimensional ultrasonic vibration-assisted turning with a dual-frequency drive can improve the machinability of workpieces. The output path of the vibrating tool nose in this method is a complex Lissajous closed curve, which results in the change of the instantaneous cutting force generated by the vibrating tool at different times. Therefore, when evaluating the instantaneous cutting force of this method, it is necessary to determine the equivalent plane at the cutting point at different times, and the orthogonal transient cutting force model is established in the equivalent plane. The effects of ultrasonic vibration and machining parameters on the cutting force generated by three-dimensional ultrasonic vibration-assisted turning are analyzed. It shows that the reasonable selection of ultrasonic vibration displacement and machining parameters can obtain lower cutting force. Among them, the vibration displacement in the cutting speed direction and the cutting depth have the largest contribution to the cutting force. Finally, a single-factor comparison experiment was carried out for different turning methods. It shows that when the cutting parameters are changed, the development trends of the cutting forces generated by the four turning methods are roughly the same. It also shows that the vibrating tool with a complex Lissajous curve trajectory can effectively weaken the cutting force. The research results of the manuscript provide a theoretical basis and guidance for the development of three-dimensional ultrasonic vibration-assisted cutting methods.

Minimizing Tool Wear, Cutting Temperature and Surface Roughness in the Intermittent Turning of AISI D3 Steel Using the DF and GRA Method

Intermittent turning (IT) is characterized by a different context than continuous turning (CT). The cutting tool is shocked each time it goes off-load and engages a new surface. This interruption causes severe cutting conditions, which fatally affect the performance parameters. The purpose of this study is to assess the effects of four cutting factors, tool nose radius (r), cutting speed (Vc), feed rate (f), and depth of cut (ap), on the following output performance parameters: surface roughness (Ra), cutting temperature (T°), and cutting tool wear (VB) during turning (IT) AISI D3 cold work tool steel. A triple CVD (AI2O3/TiC/TiCN)-coated carbide cutting tool was used. A Taguchi L9 (3^4) experimental design was adopted for carrying out the experiments in intermittent turning. To improve the performance parameters based on three (3) highly particular scenarios that fulfill industrial criteria, the desirability function (DF) and the grey relational analysis method (GRA) were used. Finally, the optimization findings of the two strategies were compared in order to evaluate the performance of each method.