Side Milling Research Articles

Effects of tool coating and tool wear on the surface and chip morphology in side milling of Ti2AlNb intermetallic alloys

Effects of tool coating and tool wear on the surface and chip morphology in side milling of Ti2AlNb intermetallic alloys

Analytical modelling for residual stress prediction in multi-step side milling of GH4169 thin-wall parts based on deformation

GH4169 thin-walled parts are widely used in aerospace due to their high-temperature, corrosion resistance, and fatigue strength. However, they often deform from machining-induced residual stress, which is a significant unresolved manufacturing challenge. Additionally, initial residual stress from previous steps critically impacts subsequent processes. This study found that the residual stress of side milling of thin-walled parts under smaller cutting parameters is mainly caused by mechanical effects, and the influence of milling heat can be ignored. In this study, an analytical prediction model for residual stress of multi-step side milling thin-walled parts based on the deformation of thin-walled parts is proposed for the first time, which is suitable for smaller cutting parameters. Then, the proposed model is examined the mechanisms through which residual stresses develop during side milling and defined the applicability of model based on specific assumptions. To validate these assumptions, an experimental setup was devloped to simulate the movement of the heat source during milling. Subsequent two-step side milling experiments on GH4169 confirmed the accuracy of the analytical prediction model in predicting the residual stresses of multi-step side milling in thin-walled parts. It was observed that higher equivalent bending stiffness in thin-walled parts correlates with reduced machining deformation. The analytical model also provides a strategic approach to control machining deformation by managing the equivalent bending stiffness of the parts.

A comprehensive guide to milling techniques for smoothing the surfaces of 3D-printed thermoplastic parts

PurposeThis study aims to thoroughly examine the milling process applied to fused filament fabrication (FFF) parts. The primary objective is to identify the key variables in creating smooth surfaces on FFF specimens and establish trends about specific parameters.Design/methodology/approachIn this study, PLA and ABS samples fabricated by FFF are subjected to side milling in several experiments. Achievable surface quality is studied in relation to material properties, milling parameters, tooling and macrostructure. The surface finish is quantified using profile measurements of the processed surfaces. The study classifies the created chips into categories that can be used as criteria for the anticipated quality. Spectral analysis is used to examine the various surface formation modes. Thermal monitoring is used to track chip formation and surface temperature changes during the milling process.FindingsThis study reveals that effective heat dissipation through proper chip formation is vital for maintaining high surface quality. Recommended methodology demands using a tool with a substantial flute volume, using high positive rake and clearance angles and optimizing the feed-per-tooth and cutting speed. Disregarding these guidelines may cause the surface temperature to surpass the material’s glass transition, resulting in inferior quality characterized by viscous folding. For FFF thermoplastics, optimal milling can bring the average surface roughness down to the micron level.Originality/valueThis research contributes to the field by providing valuable guidance for achieving superior results in milling FFF parts. This study includes a concise summary of the theoretically relevant insights, presents verification of the key factors by qualitative analysis and offers optimal milling parameters for 3D-printed thermoplastics based on systematic experiments.

Effects of longitudinal ultrasonic vibration on tool wear behaviors in side milling of GH4169D superalloy

The GH4169D superalloy, a novel Nickel-based material widely acknowledged for its exceptional high temperature strength and fatigue resistance properties, plays a pivotal role in the production of critical components of contemporary aero-engines. The material, however, falls under the category of a typical difficult-to-cut metallic material due to the substantial cutting forces and significant tool wear experienced during the machining process. In this paper, a method of longitudinal ultrasonic vibration assisted side milling (LUVM) was developed to extend tool life. The investigation primarily involved an analysis of tool wear behaviors, including milling force, tool life, morphologies of tool wear, and various underlying wear mechanisms in LUVM and conventional milling (CM) of GH4169D superalloy. The results demonstrate that LUVM exhibits the advantage of reducing milling forces and prolonging tool life in comparison to CM. Throughout the entire milling process, the maximum milling force of LUVM is consistently smaller than that of CM, displaying a comparatively slower growth trend. At the conclusion of machining, while CM reaches a maximum milling force of 360.3 N, the maximum milling force of LUVM (195.9 N) is significantly lower. The tool life of LUVM is 28.2 min, representing a 33 % increase compared to CM (21.2 min). Material adhesion, coating delamination, and built-up edge (BUE) phenomena can be observed on both the tool rake face and flank face in CM. LUVM contributes to mitigation of bonding phenomena, prevention of BUE formation, and avoidance of abrasive wear in comparison to CM. However, it is prone to lead to tool tip chipping. For CM, the tool wear mechanisms include adhesive wear, oxidation wear, abrasive wear and diffusion wear; whereas for LUVM, the tool wear mechanisms comprise of adhesive wear, oxidation wear and diffusion wear.

Optimization of machining path for integral impeller side milling based on SA-PSO fusion algorithm in CNC machine tools

The five axis linkage Computer Numerical Control machine tool for integral impeller can achieve blade machining through side milling, which is of great significance for improving the machining accuracy, production efficiency, and long-term stability of integral impeller blades. This study is based on non-uniform rational B-spline curves and aims to reduce the surface over cutting or under cutting of integral turbine blades. The path planning of non deployable ruled surfaces was analyzed in depth through side milling, and the path planning model of the side milling cutter axis was solved through a fusion algorithm of simulated annealing algorithm and particle swarm optimization algorithm, in order to find the optimal path through iterative process. As the number of iterations increased, the error values of particle swarm optimization algorithm and simulated annealing particle swarm optimization fusion algorithm gradually decreased, with convergence times of about 7 and 6, respectively. The stable error value of the fusion algorithm was 0.253, which is 30.45% lower than that of the particle swarm optimization algorithm. The optimal number of iterations for solving the model using particle swarm optimization algorithm and fusion algorithm was the 7th, with range values of 0.0213 and 0.0165 mm, respectively. The tool axis trajectory surface optimized by the fusion algorithm was closer to the tool axis motion state compared to the initial tool axis trajectory surface. The range of the sum of mean squared deviations for single and global cutting was 0.0011–0.0198 and 0.046–0.0341, but the overall error value was relatively small. This study effectively reduces the envelope error of machining tools and improves machining accuracy, thereby solving the principle error of non expandable ruled surfaces in the motion trajectory of the blade axis of the integral turbine. This provides new research ideas for the intelligent development of Computer Numerical Control machining technology.

The Dynamic Comprehensive Evaluation of the Importance of Cutting Parameters in the Side Milling TC4 Process Using an Integrated End Mill.

In the cutting process, there are many parameters that affect the cutting effect, and the same parameter has different degrees of influence on different performance indicators, which makes it difficult to select key parameters for parameter optimization and parameter combination evaluation while considering multiple performance indicators at the same time. The process of titanium alloy milling with an integrated end mill is studied herein. The values of cutting tool flank face wear and material removal rates are obtained with experimental and analytical methods. Numerical characteristics and causes of the cutting tool flank face wear at different stages are also analyzed. The dynamic, comprehensive evaluation method based on the double incentives model is used to evaluate the dynamic, comprehensive importance of cutting parameters in view of the problem of considering multiple performance indicators and the characteristics of the dynamic change in performance indicators in the cutting process. According to the result of a dynamic, comprehensive evaluation, the cutting parameters with the highest comprehensive importance are selected. Finally, the radar map is used to plot the comprehensive importance of the cutting parameters. The overall comprehensive importance of each cutting parameter is intuitively displayed as well. As a result of the research, the dynamic, comprehensive evaluation method based on the double incentives model has a good application value in the evaluation of tool performance in the cutting process and can quickly select the best tool performance parameter combination; it is established that the most comprehensive parameter is the cutting speed, and the cutting width is the second most important. In turn, the comprehensive importance of the cutting depth is the lowest.

Research on the stability prediction for multi-posture robotic side milling based on FRF measurements

In robotic side milling, frequent chatter extremely restricts the acquisition of high surface quality due to weak stiffness, and cutting parameters optimization guided by stability boundary is regarded as an effective solution to solve the chatter problem. In this research, the influence mechanisms of stability were analyzed by evaluating the structural static stiffness and dynamic parameters, and the main factor was characterized as regenerative chatter by means of stability measurements and the theoretical prediction model. The distance-driven multi-posture frequency response function (FRF) prediction model was improved in terms of the dominant modal. Grey correlation analysis was carried out to investigate the influence law of robotic joints to modal parameters, and the difference between far-distance posture and near-distance posture was re-characterized by cross-validation of FRF measurements. Finally, the third-order Hermite–Newton approximation was employed to solve the dynamic model by considering process damping effect, and the results showed the prediction accuracy of the constructed stability boundary was over 85%.

Construction of a Cutting-Tool Wear Prediction Model through Ensemble Learning

This study begins by conducting side milling experiments on SKD11 using tungsten carbide TiAlN-coated end mills to compare the surface roughness performance between two combinations of milling process parameters (feed rate and radial depth of cut), along with three ultrasonic-assisted methods (rotary, dual-axis, and rotary combined with dual-axis). The results suggest that the rotary (z-axis oscillation) ultrasonic-assisted method may provide better performance. Subsequently, this superior ultrasonic-assisted method was applied both with and without laser locally preheating assistance, respectively. Using a Taguchi orthogonal array, milling process parameters (spindle speed, feed rate, and radial depth of cut) were planned for experiments with the same cutting tool and the workpiece just mentioned above. The surface roughness serves as the objective function while being constrained by cutting-tool life. The characteristics of the smaller-the-better in the Taguchi method were applied to determine the optimal combination of process parameters. Based on the optimal milling process parameters obtained and the superior hybrid-assisted method adopted, milling experiments were repeatedly performed to collect the data on cutting force and cutting-tool wear. Feature engineering was performed on the cutting force signals, and different domain characteristics from both the time and frequency domains were extracted. Hereafter, feature selection by random forest and data standardization were further applied to feature extractions, and the data processing was thus completed. For the processed data, a cutting-tool wear prediction model was constructed by ensemble learning. This method leverages various machine learning regression models, including decision tree, random forest, extremely randomized tree, light gradient boosting machine, extreme gradient boosting, AdaBoost, stochastic gradient descent, support vector regression, linear support vector regression, and multilayer perceptron. After hyper-parameter tuning, the ensemble voting regression prediction was performed based on these ten mentioned models. The experimental results demonstrate that the ensemble voting regression model surpasses the performance of each individual machine learning regression model. In addition, this regression model achieves a coefficient of determination (R2) of 0.94576, a root mean square error (RMSE) of 0.24348, a mean squared error (MSE) of 0.05928, and a mean absolute error (MAE) of 0.18182. Therefore, the ensemble learning approach has been proven to be a feasible and effective method for monitoring cutting-tool wear.

Fast texturing of micron grating on curved metallic surfaces using bending-torsional-coupled rotary ultrasonic side milling

Structural coloration by texturing micron gratings has been regarded as a promising approach for anticounterfeiting and functional decoration. However, the fabrication of micron gratings on curved surfaces is still challenging, restricting the application of structural colors. Taking advantage of the superior capacity of milling process in the machining of curved surfaces, this study proposes a novel texturing method for micron grating on curved surfaces by adopting bending-torsional-coupled rotary ultrasonic side milling (BTC-RUSM). The generation of gratings is governed by a “cutting and microforming combined process” in each vibration cycle induced by the bending-torsional-coupled vibration of the tool. The gratings with a spacing of 0.81 μm to 3.55 μm, controlled by the spindle rotation speed, are successfully fabricated. Structural coloration with colorful characters has been achieved on the curved surface.

Suppression of cutting vibration in side milling of laser cladded layer on thin-walled parts with interfacial structures

Laser cladding is being employed for repairing high-end components including thin-walled parts. The heterogeneous interface between cladding layer and substrate can exacerbate cutting vibration during subsequent machining, becoming a bottleneck in remanufacturing thin-walled parts. This paper focuses on exploring the effect of interfacial structures on cutting vibration suppression in side milling of laser cladded layer on thin-walled parts. First, the interfacial structure was proven to be effective for suppressing cutting vibration by increasing modal damping, although the stiffness shows a decreasing trend. Among different interfacial structures, triangular structure showed the best role in cutting vibration suppression, followed by rectangular, semi-circular, and trapezoid. Then, the effects of different structural parameters on cutting vibration suppression were further analyzed based on a Taguchi design. The results showed that the cutting vibration decreases with the smaller interfacial shape factor, larger depth and smaller spacing of interfacial structures. The interfacial structure would be optimal when the interfacial shape factor is 0.06, the interfacial depth is 3.0 mm, and the spacing is 0 mm. As a result, the cutting vibration during milling was reduced by 55.28 %. These findings provide a theoretical basis for high-quality remanufacturing of the thin-walled parts.

Parameter Selection for Milling Machining of Thin-Walled Parts Based on Spatial Distribution of Side Blades

In the machining of thin-walled components, the tool’s side edges play a pivotal role in the cutting process. This paper presents the establishment of the AdvantEdge 3D simulation model for the analysis of the contact conditions and the variation in cutting forces between the side edge and the machined surface across varying cutting depths. Subsequently, milling experiments were conducted to assess the impact of the side edge’s contact conditions on the surface quality of the machined parts, considering different cutting depths. The findings reveal that during side milling of thin-walled components, a lower number of teeth result in reduced cutting edges, decreased cutting forces, and improved surface quality. The selection of cutting depth should be made with due consideration to the contact conditions between the tool’s side edge and the workpiece. Ideally, the cutting depth should be less than the pitch of the side edge’s spatial curve to ensure that only a single cutting edge is engaged in the cutting process.

Wear characteristics and performance in side milling of Ti2AlNb intermetallic alloys with coated and uncoated end mills

Ti2AlNb intermetallic alloy is highly suitable for aerospace key component manufacturing due to its low density, exceptional temperature strength, high specific strength, and creep resistance. However, the poor machining quality and severe tool wear appear, because of their poor thermal conductivity and excellent high temperature strength performance. In this paper, the coated and uncoated end mills are performed to investigate the tool wear characteristics during side milling of Ti2AlNb intermetallic alloys. In addition, the milling forces, tool service life, tool wear morphologies and mechanisms are discussed in detail. Results indicate that the coated and uncoated end mills suffered severe tool wear in the side milling process, leading to a rapid increase in milling forces. The coated end mill exhibited a longer service life of tools than the uncoated end mill. The service life of coated end mill reaches 6 min, primarily limited by flank wear and accompanied by chipping, whereas the uncoated end mill had a service life restricted to 2 min due to tool tip breakage. Tool wear morphologies of coated and uncoated end mills include rake face wear and flank face wear. Typical characteristics (e.g., crater wear, built-up edge, chipping and adhesion) are observed on the rake face of the both coated and uncoated end mills. On the flank face of the coated end mill, the chip adhesion, micro-chipping, chipping and coating delamination are found, whereas only chip adhesion and micro-chipping appear for uncoated end mill. Furthermore, the primary mechanisms of wear for both coated and uncoated end mills are adhesive wear and oxidation wear, which occur on both the rake face and flank face.

Surface wear resistance and microstructure characteristic in longitudinal–torsional ultrasonic vibration side milling of GH4169 superalloy

The intrinsic link between the surface wear resistance and microstructural evolution of a material was revealed. The surface wear resistance of the GH4169 superalloy was systematically investigated in relation to the surface machining topography and mechanical properties at different cutting widths in conventional side milling (CSM) and longitudinal–torsional ultrasonic vibration side milling (LTUVSM). The wear resistance was evaluated by analyzing the wear topography, friction coefficient, duration of the initial wear stage (IWS), and wear volume of dry sliding wear. The specimens in LTUVSM exhibited higher wear resistance than those in CSM owing to the inhibition of friction and growth of inter-surface friction nodes by the uniform ultrasonic vibration texture (UVT) and the inhibition of subsurface crack nucleation and extension by the superior mechanical properties. The mechanism of the ultrasonic vibration intervention in grain refinement was revealed. The involvement of ultrasonic vibration enhanced the dislocation accumulation, the grain boundary fractures, and increased the recrystallization fraction, which resulted in a thorough grain refinement with a 7.3 % decrease in average grain diameter (AGD) relative to that obtained with CSM. The increased grain refinement in LTUVSM improved the mechanical properties of the surface-layer material, thereby improving the wear resistance of the specimen.

Experimental investigations of impact behavior and milling performance of T700-CFRP under cryogenic conditions

The carbon fiber reinforced plastic (CFRP) composite is a reliable body material for modern airplanes, and extremely difficult to cut owing to its complex structure and special mechanical characteristics. In cutting CFRP, fiber breakage and delamination defects very frequently appear on the machined surface. The use of cryogenic cooling in CFRP cutting has proven to be an advanced approach to improving the machined surface quality of CFRP composites. To reveal the mechanism of milling CFRP under cryogenic conditions, this study investigates the impact behavior and cutting performance of T700-CFRP at low temperatures. The impact test of T700-CFRP unidirectional laminates with 0°, 45°, and 90° fiber directions was performed at various temperatures ranging from 20 °C to −196 °C, to analyze the impact toughness and the fracture morphology. Side milling experiments of CFRP laminates of 0°, 45°, and 90° fiber directions with the PCD endmill were conducted at the same temperatures used in the impact test. Experimental findings revealed that for 0° specimens, the impact toughness increased at lower temperatures, and the impact damage worsened as the temperature dropped from −120 °C to −196 °C. There were no evident changes in the impact toughness or impact damage of 45° and 90° specimens with the decrease in temperature. The feed force and radial force increased as the cooling medium temperature lowered during milling CFRP. The machined surface of 45° workpieces was the roughest among all the workpieces and covered with numerous pits and craters. The machined surface roughness Ra of 0° workpieces decreased as the cooling medium temperature was lowered from 20 °C to −160 °C and then increased at −196 °C, while the Ra value of both 45° and 90° workpieces rose as the temperature dropped from 0 °C to −196 °C.

Research on design and milling performance of unequal gradient helix and variable pitch end mill

It is difficult to obtain excellent surface quality and dimensional accuracy of the low-rigidity frame and beam parts made by titanium alloy, due to the obvious vibration and large elastic deformation during side milling. The variable helix and pitch cutting tool is usually used to reduce vibration, which does not consider the unequable stiffness in the milling area. Therefore, the concept of Unequal Gradient Helix and Variable Pitch (UGHVP) is proposed in this research. The helix angles of the UGHVP vary with the stiffness of the milling area position, which will lead to milling forces and vibration decreasing as the stiffness weakens. As a result, the surface quality and dimensional accuracy will be increased, of which the advantages are analyzed. The mathematical models of the UGHVP circumferential cutting edges and groove sections are derived, which provide theoretical support for tool grinding. The models are visualized by numerical simulation. Finally, the comparison experiment with the conventional variable helix and pitch end mill was completed by side-milling the designed feature samples. The results showed that the milling forces perpendicular to the milling surface by the UGHVP were smaller and less fluctuating, which could obtain less elastic deformation theoretically. The milling vibration was smoother, especially when cutting in and out. Besides, the larger the axial depth of cut, the more obvious the superior performance of the UGHVP tool. Better surface quality and dimensional accuracy were obtained, which proved the excellent performance of the UGHVP.

Predicting tool life for side milling in C45 E using Colding and Taylor tool life models

This paper investigates the possibility of using empirical tool life models to predict tool life in a side milling application in a medium carbon steel, C 45E. To do this, an extensive dataset containing 46 data points with different machining parameters are produced. Four different empirical models: Taylor’s equation, Colding’s equation and Extended Taylor both using depth of cut and feed as well as an Extended Taylor using equivalent chip thickness has been considered. It is found that Colding’s equation is best suited to predict the tool life for this application. Furthermore, this paper suggests a novel method to fit the experimental data to the empirical models. Based on the results from previously published papers it is shown that the proposed method performs equally or better to determine the model constants.

A comprehensive research on wear resistance of GH4169 superalloy in longitudinal-torsional ultrasonic vibration side milling with tool wear and surface quality

To improve the service and machining performance of the workpiece, the tool wear mechanisms, surface machining quality, and wear resistance in conventional side milling (CSM) and longitudinal-torsional ultrasonic vibration side milling (LTUVSM) of GH4169 superalloy at different cutting lengths are investigated systematically. Tool wear mechanisms are revealed and the correlation between machined surface quality with tool wear is analyzed correspondingly. Tool wear patterns mainly include adhesive wear, diffusion wear, abrasive wear, and chipping sticking. Better surface quality is achieved in LTUVSM due to a maximum reduction of flank wear bandwidth and wear rate by 71.9% and 71.5%, respectively, compared to CSM. The friction coefficient, initial wear stage time, and wear volume of dry sliding wear were measured to evaluate the workpiece wear resistance. The maximum reductions in friction coefficient and wear volume in LTUVSM are 18.2% and 15.8% compared to CSM. The regular ultrasonic vibration textures suppress the friction and the growth of contact nodes in the contact area, decreasing the degree of surface wear, which is demonstrated by a 38.8% increase in initial wear stage time compared to CSM. In conclusion, the workpiece in LTUVSM exhibits higher wear resistance because of the improvement of tool wear and the guarantee of surface quality.

A comparative experimental study of unidirectional CFRP high-speed milling in up and down milling with varied angles

Precision machining of Carbon Fiber Reinforced Polymer (CFRP) is challenging due to its high strength and anisotropic microstructure. This study proposes a specially designed cutting experiment method to understand the influence mechanism of cutting force and surface quality in CFRP high-speed cutting process. The study examines the influence of fiber cutting angle, up/down milling, and machining parameters on the side milling of regular 12-corner unidirectional CFRP samples. Cutting force and surface quality are evaluated to analyze the machining process. The results show that the cutting angle is a key factor influencing milling force and surface quality. For cutting along the fiber, force follows 60° > 30° > 90° > 0°, and against the fiber, it follows 90° > 180° > 150° > 120°. The 90° cutting angle provides optimal surface quality, and cutting against the fiber facilitates material removal. Up-milling can reduce cutting force by 15 %–20 % and surface roughness Sa by up to 25 % compared to down-milling, while improving tool durability. High-speed cutting can reduce surface roughness by at least 35 %. These findings can optimize CFRP machining processes and improve quality results.

Методика критериального анализа мультивариантных систем

Introduction. Trends in the development and application of modern machine-building systems somehow create the problem of analysis and choice in the presence of alternative objects, or with a large number of comparison criteria - indicators of the effectiveness of objects or systems. The main difficulties in optimizing the solution for designing production systems depend on complex technological problems: a large number of influencing factors and the absence of patterns. The choice of effective objects and systems is often a complex and multi-criteria process that requires a lot of time and, as a result, reduces the efficiency of the organization of production preparation. In this regard, for the preparation and adoption of technical and economic decisions of various complexity in production conditions, a systematic approach is required using the most rational forms and methods of organizing production. The purpose of the work: to create a generalized methodology for the criteria analysis of multivariant systems. The methods of investigation. A methodology is proposed aimed at improving the efficiency of the organization of pre-production due to a reasonable choice from a large number of options. The choice of a rational solution option is based on the ranking of indicators by priority at the time of making a reasonable decision in a specific situation and the type of object and system under consideration. Indicators can be variable, taking into account the specifics of production. Results and Discussion. A comparative analysis of the process of edge cutting machining of the STEF-1 fiber-glass polymer composite material with an interlocking side mill carrying various insert materials is conducted as an example of the practical application of the proposed methodology. As comparison parameters, the period of technological tool life, cutting performance and reduced costs in the implementation of cutting are taken. According to the results of a comparative multi-criteria analysis carried out according to the presented method, it follows that the priority in the system under consideration with the specified parameters for the implementation of the technology is the tool equipped with WC–3Co alloy inserts, which has the highest value of the weight criteria coefficient. According to the results of the analysis, a tool equipped with WC–2TaC–6Co alloy inserts is close in rationality, which allows recommending it as an analogue when choosing. The scope of the proposed application of the methodology is seen if it is necessary to analyze complex multivariant systems/objects. The objects/systems can be both variants of scientific solutions under various conditions of comparability, as well as design, technological solutions, structural and instrumental materials at the selection stage in the design and technological preparation of production, variants of the system implementation algorithm. The comparison parameters can be physical, mechanical, technological, operational properties; technical, economic and quality indicators; specific characteristics and parameters. The proposed technique will reduce the time for making new decisions under varying production conditions. The use of the methodology with known and well-defined parameters characterizing multivariant systems makes it possible to algorithmize, and subsequently automate, the process of organizational and technological preparation of production.

Milling mechanism and surface roughness prediction model in ultrasonic vibration-assisted side milling of Ti–6Al–4 V

Milling mechanism and surface roughness prediction model in ultrasonic vibration-assisted side milling of Ti–6Al–4 V