Chip Formation Analysis Research Articles

Chip formation analysis during dry turning of C45 steel

Machining is a material removal process that creates surfaces through chip formation using a cutting tool. The morphology of the chips and the mechanisms governing their formation directly affect the quality of machined parts. This experimental study examines chip formation mechanisms in the dry turning of C45 steel under various cutting conditions, utilizing coated carbide inserts. Machining performance was evaluated based on key chip morphology parameters, including shape, length, thickness, and volume. The results show that increasing cutting speed (Vc) produces shorter, thicker chips without significantly altering their predominantly helical shape. A higher feed rate (f) maintains the tangled ribbon form of the chips but leads to longer chip production. Additionally, changes in the depth of cut (ap) create instabilities that result in varied chip morphologies, including long tubular, short helical, and elementary forms. As the depth of cut increases, chips become shorter and thinner. These findings provide valuable insights into the material's deformation and fracture mechanisms, enhancing our understanding of chip formation and its impact on the efficiency of dry turning operations on C45 steel.

Tool chip contact length analysis of dry and cryogenic turning of aerospace alloy Ti-6Al-4V

Tool chip contact length is a vital machining index being representative of manufacturing efficiency. Various machining factors including tool wear and energy consumption are governed by tool chip contact length. The current work was undertaken to make a comparative analysis of dry and cryogenic turning of Ti-6Al-4V in terms of their sustainability and productivity indices. During experimentation, cutting speeds of 50 m/min and 125 m/min were selected working at feed rates ranging from 0.16 mm/rev to 0.24 mm/rev. Scanning electron microscopy was utilized to analyse the results. It was observed that machining under cryogenic conditions, in comparison with dry conditions, resulted in up to 51 % lower tool chip contact length. The results were also investigated in terms of chip formation for both machining environments. In addition, benefits of lower tool chip contact length were quantified in terms of lesser tool wear and better energy consumption. Tool chip contact length and chip formation analysis, indicative of the machining process efficiency, highlights that cryogenic condition is more sustainable and productive than dry conditions.

Chip Formation Analysis of the Turning of ST41 Steel

ST41 steel is commonly used for the shaft of ships. The shaft tends to corrode due to the interaction with the water. To recycle the used ST41, welding is normally done to repair the damaged or rusted surface of the shaft. The turning process is then conducted to obtain a better surface finish. This research used three types of cutting tools with different geometry at their cutting angle of 800 , 850 , 900 . The chips from the turning process are collected and observed. Chip formation will indicate the quality of the turning process. The chip thickness and formation are observed to determine the effect of the cutting angle on the machining quality. The chip thickness value ranges between 0.13 mm to 0.3 mm, with a cutting angle of 900 producing the thinnest chips and 850 producing the thickest chips. Thicker chips indicate higher cutting force that leads to the wear of cutting tools. The cutting angle also affects obtained the chip formation. Several shapes are obtained, such as long continuous, medium, and short discontinuous shapes. A longer chip means a better process with less chatter on the cutting process. Long continuous chips are dominantly found by using 900 cutting tool. The other two angles are dominated by the discontinuous chips, with a slightly medium length of chips majorly found at 800 and short discontinuous chips recovered using an 850 cutting tool. From this research, it could be known that a 900 cutting angle will produce thinner and better chip formation.

Surface Roughness, Topography, Accuracy, Chip Formation Analysis & Investigation of M390 and M398 Steels after Hard Machining

Article deals with processing of intermetallic materials produced by powder metallurgy M390 and M398 Microclean® produced by BĂśhler. Main interest is the analysis & measurement of their surface rough-ness and topography after the processing by DNMG and WNMG geometry of cutting inserts with 0.4 and 0.8 mm radius after hard turning at the same process parameters for both materials and all types of cutting inserts. The comparative studies were carried out for the microgeometrical and chip formation research on the machined surfaces and the technological processes were assessed, including chip dia-grams. Spectral analysis was used to verify the composition of investigated materials by spectral analysis measuring device. In order to examine the surfaces in detail, in addition to the standard roughness measurement, surface topography was performed by the coherent correlation interferometric micro-scope. The results of surface roughness as well as topography show higher wear resistance of M398 ma-terial compared to M390. This was confirmed indirectly by the fact that it is primarily shown by the higher surface roughness of M398 after machining under the same conditions. These properties are ob-tained by a higher content of additive elements, respectively of their carbides. Based on the conclusions of these experiments, additional knowledge and recommendations for the processing of these materials were created.

Performance assessment of vegetable oil-based cutting fluid developed from palm kernel oil using multi-response optimisation technique

In this work, locally sourced palm kernel oil was characterised and thereafter formulated with the aid of full factorial L1624 design method. The performances of the formulated and mineral cutting fluids were evaluated by examining the material removal rate, cutting temperature and surface roughness using Grey relational analysis (GRA) and Behnken’s design (L1533) design technique. The experimental results obtained indicate that the properties of the palm kernel oil and formulated cutting fluid falls within the preferred range for vegetable-based cutting fluids as reported in literatures. The GRA results showed an optimal turning condition of depth of cut (1.5mm), feed rate (0.3mm/rev) and cutting speed (600rev/min) for palm kernel oil-based cutting fluid while depth of cut (1.5mm), feed rate (0.2mm/rev) and cutting speed (800rev/min) is the optimal condition for mineral oil-based cutting fluid. Also, the chip formation analysis revealed continuous chips which are in conformity with ISO 3685 standards.

Kinematic Approach on Chip Formation Analysis in Gear Skiving

Although the arrangement with a shaft angle enables a pinion cutter to cut a gear by skiving in mechanism theory, it may or may not work in practical skiving depending on the tooth geometries. The present study describes chip flow in a skiving process to evaluate the machinability. The oblique cutting model allows itself to define cutting parameters, i.e., depth of cut, cutting velocity, rake angle, and relief angle. The parameters change with the progress of cutting. Therefore, they enable themselves to define the states of a chip at any instance. Merchant's theory can give chip thickness and chip flow rate after giving shear angle or friction coefficient between chip and tool face. In the present paper, assuming a linear relationship between rake angle and friction coefficient enables kinematics to apply to the analysis of chip flow, which leads to calculating the chip shapes. The comparison of them with ones obtained from practical skiving showed that their figures were quite similar except for the curling portion seen in practical ones, but indicated that their dimensions are different. That means further discussions are necessary, e.g., considering the effect of friction on the tool face.

Modeling residual stresses in hard turning with self-propelled rotary tools

Finite element (FE) models have been developed to predict average surface residual stresses during hard turning of AISI 4340 steel with self-propelled rotary tools (SPRT). Three dimensional chip formation analysis have been carried out using coupled temperature displacement analysis. In the next step, the workpiece is unloaded and allowed to cool till the attainment of room temperature using convective heat transfer model. The residual stresses in the cutting direction obtained using the FE models are validated using experimentally measured ones using X-ray diffraction technique. A good agreement has been found between the predicted and experimental values and the average errors are around 11–12%. In addition, residual stresses obtained with the fixed tool are also evaluated and compared with SPRT. The effects of cutting speed and feed rate on residual stresses using SPRT have also been analyzed and discussed.

Chip formation simulation and analysis of the mechanical loads during micro single-lip deep hole drilling of Inconel 718 with varying cooling lubricant pressure

The micro single-lip deep hole drilling process is subjected to many difficulties. Especially the machining of difficult-to-cut materials like the nickel-based alloy Inconel 718 results in high thermal and mechanical loads. Irregularities in the drilling process, which lead to early tool failures must be avoided. A major challenge for micro single-lip deep hole drilling is to generate favorable chips and guarantee good chip removal. Since the chip flute of single-lip deep hole drilling tools is straight, the only mechanism to transport the chips and remove them from the bore hole is the coolant flow. In this paper the mechanical loads and the resulting chip formation for various cooling lubricant pressures are analyzed using tools with a diameter of d = 2 mm. In the experiments feed force, drilling torque, tool wear, bore hole quality as well as diameter and roundness deviations were evaluated. Individual chips are digitized and prepared as CAD models for the future consideration of the chip removal in flow simulations of the cooling lubricant. Additional FEM computational analyses of the three-dimensional chip formation with a geometric representation of the chip shape were carried out. This way not only provides valuable validated information about the process and the chip formation but also creates a basis for further investigations, which will allow an innovative simulation of the coolant flow and considers the chip formation and the chip shape.

L16 Orthogonal Array-Based Three-Dimensional Finite Element Modeling for Cutting Force and Chip Formation Analysis During Dry Machining of Ti–6Al–4V

The outstanding characteristics of titanium alloy (Ti–6Al–4V) have made this material applicable in aerospace and medical components. However, due to its poor machinability characteristics, researchers are forced to understand the machinability behavior of Ti–6Al–4V. In this paper, [Formula: see text] orthogonal array-based three-dimensional finite element modeling for the cutting force and chip formation analysis during the machining of Ti–6Al–4V using cubic boron nitride tool in dry turning environment has been investigated. The finite element simulation was performed using ANSYS Workbench, version 19.0. Cutting force and chip formation were investigated using the results obtained from [Formula: see text] orthogonal array-based three-dimensional finite element modeling. This research would help to identify the optimum cutting conditions and minimize the cutting force followed by analyzing the types of chips formed during machining under the selected set of cutting conditions.

Evaluation of Self-Propelled Rotary Tool in the Machining of Hardened Steel Using Finite Element Models.

This paper presents a model for assessing the performance of self-propelled rotary tool during the processing of hardened steel. A finite element (FE) model has been proposed in this analysis to study the hard turning of AISI 51200 hardened steel using a self-propelled rotary cutting tool. The model is developed by utilizing the explicit coupled temperature displacement analysis in the presence of realistic boundary conditions. This model does not take into account any assumptions regarding the heat partitioning and the tool-workpiece contact area. The model can predict the cutting forces, chip flow, induced stresses, and the generated temperature on the cutting tool and the workpiece. The nodal temperatures and heat flux data from the chip formation analysis are used to achieve steady-state temperatures on the cutting tool in the heat transfer analysis. The model outcomes are compared with reported experimental data and a good agreement has been found.

Tool wear and chip formation analysis of aluminium hybrid metal matrix composite

Since last two decades technology has changed rapidly in each industry from consumer goods to aerospace. To quench the thrust of technology advancement of industries, the research community has to develop novel materials. As a part of the ongoing process of material development and machinability study, present work carried out to find out the effect of reinforcement and machining parameter variation on the cutting tool. Furthermore, chip analysis was carried out to find out the effect of reinforcement and cutting parameter variation on types of chip formed. The desirability of the chips was decided based on the surface finish value. Pure aluminium was used as a matrix material while; B4C, Mg, Ti and Graphite were used as reinforcement. It was observed that the unfavourable machining parameter reduces tool life considerably and this phenomenon was more evident in the carbide coated insert compared to PCD insert. High tool wear was observed during machining of composite material compared to the aluminium matrix. An undesired chip produced when feed increases and speed reduces. Moreover, change in reinforcement amount also has an effect on the types of chip produces. The surface roughness value up to 0.50 μm was reduced by a combination of optimized cutting parameters and change in reinforcement amount.

Tool wear assessment of turning operation by 2D finite-element simulation

Tool wear is a critical problem in industrial manufacturing. When tool wear reaches a certain value, it causes a change in tool geometry. This directly affects chip formation, cutting force, temperature distribution, machining quality and so on. Therefore, prediction of tool wear is of great importance for optimizing the cutting process. Numerical analysis is a powerful method to predicting cutting variables that are difficult to obtain by experimental method. In this paper, the effect of different tool rake angle values on tool wear rate is investigated. A two-dimensional (2D) finite-element simulation is presented for chip formation analysis considering thermal effects. Boundary conditions are defined as stationary for the workpiece and axial velocity to the tool at the cutting direction. Different models are analyzed by changing the tool geometry, and the results of the tool wear are discussed. It is shown that wear rate decreases ten times with the negative rake angle. However, increase in clearance angle causes increase in wear rate.

Analytical force model for drilling out unidirectional carbon fibre reinforced polymers (CFRP)

Abstract Carbon fibre reinforced polymer (CFRP) is characterised by a high potential for lightweight constructions due to its high specific strength and stiffness properties. Especially applications in aerospace industries necessitate numerous drilling operations in CFRP with high tolerance requirement for subsequent riveting. The bore quality in drilling CFRP is the result of complex interactions of various geometry parameters of the drilling tool, the process parameters and the material properties. Due to a strong correlation between the process forces and the resulting bore quality, analytical force models are valuable to optimise tool geometries and process strategies. Furthermore, analytical force models enable single parameter variation, which would be feasible in experiments only with excessive effort and costs. This research aims to develop an analytical force model for drilling out predrilled UD CFRP material. Based on detailed chip formation analysis by means of high-speed recordings and scanning electron microscopy (SEM), four intervals with similar chip formation mechanisms and two fundamental failure mechanisms are identified. In the modelling approach, a coordinated structural failure of entire fibre regions by axial compression is considered by micro-buckling. For fibre loading situations dominated by lateral bending deformations, fibre failure by exceeding tensile strength in the contact region is considered. Therefore, the tool-fibre contact situation is simplified as the Hertzian contact between two cylinders. In addition to force components due to an initial fibre separation in front of the cutting edge, additional force components due to elastic spring back effects of the CFRP material on the flank face are taken into account. Combined with the drilling kinematics and under consideration of oblique cutting conditions, the thrust force and the torque values are analytically determined for the entire range of fibre cutting angles during one half tool rotation. Subsequent validation shows a good agreement of simulated and experimental data.

In situ chip formation analyses in micro single-lip and twist deep hole drilling

Growing competitive pressure forces companies to optimise process productivity and shorten primary production times. At the same time, the resulting manufacturing quality must be kept on a high level. In the automotive sector, deep hole drilling with smallest tool diameters is an important process, e.g. to produce lubrication holes in crankshafts and fuel channels in injectors. A crucial criterion for the achievable productivity and manufacturing quality with respect to the dimensional and shape tolerances as well as the surface quality in smallest diameter deep hole drilling is the chip formation. Therefore, in-depth analyses regarding the mechanisms of chip formation at the cutting edge and the chip removal along the chip flutes are indispensable. To accomplish an in-depth chip formation analysis in smallest diameter deep hole drilling, a new methodology of analysis has been developed. Samples made of the particular test material are inserted into acrylic glass carriers, and the chip formation in the operating zone and the chip removal are documented by high-speed microscopy. In this paper, the experimental setup of the newly developed methodology of analysis and the experimental results for single-lip and twist deep hole drilling of high-strength bainitic steel with smallest diameters are shown. The investigations show the dependence of chip formation on the changes of the microstructure of the cutting edge due to tool wear, and form the basis for an optimization of the tools. In addition to that, a new approach to visualise machining processes running under non-transparent coolant is presented.

Development of energy consumption map for orthogonal machining of Al 6061-T6 alloy

The major source of environment and economic impact of machine tools has been attributed to their energy consumption. This article, therefore, proposes a novel energy mapping approach to evaluate specific cutting energy consumption with respect to cutting parameters. Unlike the studies presented earlier, which are machine-tool-specific, this study focuses on the basic tool–workpiece interaction for energy consumption analysis. The presented energy map reveals different energy consumption regions at varying machining parameters (feed and speed) during orthogonal machining of Al 6061-T6 alloy. The chip formation analysis indicates a strong correlation with the different energy consumption regions identified on the energy map. It has been observed that feed is the major contributing factor towards shear plane angle during chip formation as compared to cutting speed. Therefore, increasing feed results in a higher shear angle and consequently lowering the specific cutting energy as indicated on the energy map. Selection of machining parameters corresponding to the lowest specific cutting energy consumption region, as identified on the energy map, can result in energy savings up to 27% per kg of material removed. The developed map can be used for selection of suitable energy-efficient cutting parameters.

Cutting force and chip formation in end milling operation when machining nickelbased superalloy, Hastelloy C-2000

This paper presents an experimental study of the cutting force and chip formation in the end milling of the nickel-based superalloy, Hastelloy C-2000. The experiment was conducted using two different cutting inserts under wet conditions – namely physical vapor deposition coated with TiAlN, and uncoated carbide. The assessment of machining performance is based on a design of experiment. New insight into the influence of the cutting process on the cutting force and chip formation are key measures of machining performance. The effect of the machining parameters on chip formation was examined through scanning electron microscope micrographs and energy dispersive x-ray tests. The cutting forces and chip formation analysis for different sets of experiments were examined and compared in order to establish the most suitable cutting conditions, through highlighting the drawbacks and by suggesting proper measures to be undertaken during machining performance, which might overcome the barriers of machining Hastelloy C-2000.

Cutting force sensor based on digital image correlation for segmented chip formation analysis

Conventional piezoelectric sensors cannot record the force fluctuations at high frequencies to monitor serrated chip formation. Recently, force measurements by using digital image correlation (DIC) have been reported thanks to imaging devices that become more and more efficient, thereby opening possibilities of high rate acquisition. This study proposes to apply DIC based on closed-form solutions in order to measure cutting forces at camera acquisition frequency. The considered displacement fields are obtained from the Flamant–Boussinesq solution. This method is first applied to picture pairs shot during the cut and then to a full sequence of pictures recorded upon orthogonal cutting of hardened AISI 52100 steel with a c-BN tool. To validate part of the corresponding mechanism, the change of cutting forces is finally investigated when chip segments are formed.

Analysis of chip morphology and surface topography in modulation assisted machining

Modulation assisted machining (MAM), superimposing a controlled tool modulation in the feed direction of conventional machining process, can change the chip morphology and the surface topography of machined components, and finally affect the functional performances of the components. This paper is dedicated to gaining a better understanding of the chip and surface formation processes in MAM. Geometrical analysis of the tool path in face turning configuration with MAM is performed, revealing how discrete chips are generated and presenting the effects of modulation conditions on chip morphology and undeformed chip thickness. Based on the chip formation analysis, an analytical model for prediction of surface topography is developed, which takes into account tool geometries, cutting conditions, modulation conditions and the effects of plastic side flow. By using the proposed model, the influences of modulation conditions on surface topographies are shown qualitatively by laser microscope, and are analyzed quantitatively through a set of three-dimensional (3D) surface amplitude parameters. Finally, a series of turning experiments is carried out to verify the prediction of surface topography. Errors between the measured results and the predicted results are within 20% for most conditions, and the underlying sources of these errors are analyzed. This paper can serve as a theoretical basis for the further controlling of chip morphology and surface topography.

Mechanical and thermal modeling of modulation-assisted machining

Modulation-assisted machining (MAM), which superimposes a controlled tool modulation in the feed direction of conventional machining (CM) process, can generate discrete chip formation and break the severe contact condition at the tool-chip interface. The previous literatures have shown MAM effectively reduces tool wear due to its discrete regime. However, the sources of such improvement are not well developed. This paper is dedicated to reveal the nature of MAM from the perspective of mechanical and thermal modeling. Chip formation of MAM is studied in both cylindrical turning and face turning configurations, showing that variable cutting thickness, rake angle, and flank angle are the intrinsic characteristics of MAM. Based on the chip formation analysis, an analytical force model is developed to determine the dynamic cutting force in MAM, incorporating material properties, tool geometry, cutting conditions (i.e., cutting velocity, feed rate, and depth of cut), and modulation conditions. The proposed force model is verified by orthogonal cutting experiments. Then, a thermal model is proposed to investigate the temperature variation in MAM and the effects of modulation conditions on temperature as well. The thermal model is validated by both finite element simulations and turning experiments. This paper can serve as a theoretical basis for further investigations on tool wear and surface integrity.

Experimental Investigations of Machinability in the Turning of Compacted Graphite Iron using Minimum Quantity Lubrication

Unique mechanical properties of the compacted graphite iron (CGI) attracted attention of manufacturers and suppliers mainly in automotive industry in last decades. However due to the low machinability of the CGI material, more efficient machining strategies need to be implemented. Improvement in the cost-effective and environmentally sensitive processing of compacted graphite iron (CGI) is one of the major concerns of the manufacturing world because of the allure of CGI's mechanical properties. This study assesses the efficiency of minimum quantity lubrication (MQL) in CGI turning when compared to the dry-cutting condition. The turning tests were conducted across a wide range of cutting parameters: three different cutting speeds (100, 200, 300 m/min) and three different feed rates (0.1, 0.2, 0.3 mm/rev), all at a constant depth of cut (1 mm). The MQL efficiency is evaluated through cutting force and surface roughness measurements, optical and SEM analyses of chip formation and tool-wear analysis. The results showed that MQL usage provided a reduction in the resultant cutting forces by 2–5%, a reduction in surface roughness by 25%. The SEM analysis also revealed much clearer and smoother cutting edges on tool surfaces used in the MQL tests.