Side Milling Research Articles

Finite Element Analysis and Parameter Influence of Non-developable Ruled Surface Impeller Blade in Flank Milling

Through the cutting simulation of titanium alloy impeller blade, the effect of the actual milling processing path on the elastic part deflection to of complicated thin-walled workpiece with low rigidity and high precision is studied. Use the principle of impeller modeling to model the spline of the impeller, and the spline curve of the impeller generated in MABLEB is imported into UG for digital modeling. The spline curve is used to generate the neutral surface, and the suction surface and pressure surface are obtained by the method of non-equidistant offset. The model of the non-stretchable straight surface blade is imported into ABAQUS for static simulation. Using MATLAB to fit the experimental data in the reference literature that fits the milling process range, the side milling experience formula is fitted. Calculate the equivalent milling force corresponding to different axial cutting depths, import into ABAQUS and use Python for secondary development. By simulating the milling process through the life-and-death element method, the local elastic deformation law of the milled thin-walled parts when multi-layer milling the impeller blades is explored. The influence of different machining paths on the deformation of the tool is studied. Simulation results show that the part deflection of workpiece can be reduced by rationally planning the machining path.

Improved dynamic cutting force modelling in micro milling of metal matrix composites part II: Experimental validation and prediction

The effects of cutting dynamics and the particles' size and density cannot be ignored in micro milling of metal matrix composites. This article presents the improved dynamic cutting force modelling for micro milling of metal matrix composites based on the previous analytical model. This comprehensive improved cutting force model, taking the influence of the tool run-out, actual chip thickness and resultant tool tip trajectory into account, is evaluated and validated through well-designed machining trials. A series of side milling experiments using straight flutes polycrystalline diamond end mills are carried out on the metal matrix composite workpiece under various cutting conditions. Subsequently, the measured cutting forces are compensated by a Kalman filter to achieve the accurate cutting forces. These are further compared with the predicted cutting forces to validate the proposed dynamic cutting force model. The experimental results indicate that the predicted and measured cutting forces in micro milling of metal matrix composites are in good agreement.

Effects of tool vibration on surface integrity in rotary ultrasonic elliptical end milling of Ti–6Al–4V

Titanium alloys have been applied in aerospace, biomedical, and chemical industries due to their superior mechanical properties. As a novel machining method, rotary ultrasonic elliptical machining has been successfully introduced into high-speed side milling of Ti–6Al–4V recently. However, the surface integrity in end milling of titanium alloy using this method is still unclear. In this study, a comprehensive experiment on surface integrity in rotary ultrasonic elliptical end milling of Ti–6Al–4V was conducted at various vibration amplitudes and cutting speeds. Results show that regular substantial micro-vibration textures in the form of separated ridges are obtained on the machined surfaces in RUEEM. Surface roughness values rise from Ra 0.160 μm to Ra 0.758 μm with the increasing cutting speed and vibration amplitude. Both the thickness of subsurface deformed layer and the value of surface micro-hardness increase with rising amplitude at low cutting speeds, while the hardening effect gradually weakens as the cutting speed increases to 160 m/min. Besides, the values of surface compressive residual stress gradually decrease with vibration amplitudes at low cutting speeds, while opposite trends show at the high cutting speed (160 m/min). This study can provide a new method for the effective control of the surface integrity for high-speed end milling of titanium alloy.

The Effect of Milling Cooling Conditions on the Surface Integrity and Fatigue Behavior of the GH4169 Superalloy

The GH4169 superalloy has high strength at high temperatures. Cooling conditions have a major impact on the machined surface integrity, which further affects the fatigue properties of specimens of the GH4169 superalloy. The influence of cooling conditions on the surface integrity of the GH4169 superalloy is first studied during the side milling. Then, the effect of surface integrity under different cooling conditions on the fatigue behavior of specimens of the GH4169 superalloy is investigated by a standard tensile and tensile–mode fatigue testing. The results obtained show that surface roughness and the depth of the plastic deformation layer in wet milling and dry milling makes little difference, the surface microhardness rate in dry milling is slightly lower than that in wet milling, the surface tensile residual stress in dry milling is significantly higher than that in wet milling, and the fatigue behavior in dry milling is only about 50% of that in wet milling. In addition, the crack initiation of specimens of the GH4169 superalloy utilizing wet milling is on the subsurface, while that from dry milling is on the surface. Thus, cooling conditions have an important impact on the fatigue behavior of specimens of the GH4169 superalloy, and micro defects in dry milling are the main factors of decreasing of fatigue behavior of specimens of the GH4169 superalloy.

Milling investigations and yield strength calculations for nickel alloy Inconel 625 manufactured with laser powder bed fusion process

Additive manufacturing processes such as laser powder bed fusion (LPBF) are progressively implemented in industry due to increased flexibility and ability to produce complex geometries. However, the required dimensional and surface quality cannot be achieved even tough nearly fully dense net-shaped components are manufactured. Precision surfaces for design requirement can only be achieved with subsequent machining processes. Therefore, in this paper, milling investigations on nickel alloy Inconel 625 workpiece samples that were built using LPBF-based additive manufacturing process have been conducted. The samples were fabricated using different layer-to-layer scan strategy rotations. The side milling experiments were performed on machining of surfaces in horizontal (XY) and vertical (Z) orientations. It was observed that machining forces were influenced by the relative engagements of cutter feed direction and workpiece built directions. When milling cutter was fed against the vertical direction, lower peak forces with higher deviations were recorded. On the contrary, feeding the milling cutter along the vertical build direction resulted in higher peak forces with lower deviations. By using metal cutting principles, shear yield stress and yield strength at each milling case and relative engagements were identified. The results indicate that the yield stress is higher along the horizontal (XY) orientation and affects the milling forces and it is lower vertical (Z) build direction however, a scan strategy rotation of 90° layer-wise built provides an increase in yield strength as well as at higher cutting speeds due to strain-hardening behaviour of additively fabricated Inconel 625 material.

Research on deformation law and mechanism for milling micro thin wall with mixed boundaries of titanium alloy in mesoscale

At mesoscale, the blade of micro impeller with Ti-6Al-4V titanium alloy (micro thin wall with mixed boundaries) is a thin-walled structure, characterized by small size, low stiffness, high surface precision, complex boundaries, and difficult-to-control machining deformation. To control and reduce the deformation of micro thin wall, it is necessary to study the micro-deformation mechanisms during milling micro thin-wall parts. In side milling of micro thin wall with mixed boundaries, the micro thin wall suffers from dynamic alternating forces, and the deformation modes are complex, so the direct and accurate theoretical modelling is difficult to make. Since the feed speed in milling micro thin wall is less, the small deformation of micro thin wall can be described based on the flexure deformation model of the thin plate subjected to elastic loadings. Firstly, accompanied by the reciprocal theorem of work for a curved thin plate, Kirchhoff-Love small deformation model of micro thin wall is used to establish the deformation equation and boundary conditions of micro thin wall with mixed boundaries under concentrated milling forces. Thus, the obtained boundary conditions are mainly applied to the subsequent finite element simulation of three-dimensional milling deformation of micro thin wall. Then a three-dimensional deformation simulation of the micro thin wall under different milling parameters is carried out by considering the micro-walled structure, material elasto-plastic constitutive model, the stiffness and geometric structure of micro milling tools in finite element method. In the workpiece constitutive modelling, considering the strain gradient plastic model in micro milling of Ti-6Al-4V titanium alloy, the workpiece plastic constitutive model is modified by introducing the intrinsic characteristic length of the material to describe the size effects in mesoscale micro milling. Finally, a series of the corresponding experiments on the milling of titanium alloy micro thin walls are carried out. By comparing and analyzing the experimental values and finite element numerical results of the micro thin-walled deformation, the micro deformation mechanisms in milling of thin wall are revealed. It also verifies the accuracy and effectiveness of this established milling finite element model of thin wall, and provides theoretical basis and technical support for controlling the milling deformation of micro thin-walled parts.

Failure Analysis of Super Hard End Mill HSS-Co

Abstract The failure of tools will make a large impact to the productivity, so it must be investigated to avoid the next failure. In this case, the super hard end mill HSS-Co list 4SE code 6210 was broken when it was used for side milling processing of mild steel AISI A36 with rotation speed, cutting speed and cutting depth of 540 rpm, 0.10 m/min (4 ipm) and 16 mm respectively. Standard procedure of failure analysis was performed including macro-micro investigation using Scanning Electron Microscopy (SEM) with energy-dispersive spectrometry (EDS) attachment, micro hardness test, and Finite Element Methods (FEM) simulation. The results of failure analysis showed that fracture occurred due to stress concentration and micro defects of the super hard end mill. Two parts of fracture surface, rough and fine surface were found. Based on SEM-EDS investigation, it was known that the content of tungsten (W) and cobalt (Co) elements on the rough and fine surface was inhomogeneous. Excessive Co and W elements appeared on the fine surface while they disappeared on the rough surface. Excessive Co will diffuse with tungsten and carbon and lead to the separation of tungsten and carbon elements, so it greatly destroyed the alloys and lead to form the non-stoichiometry carbide points. Hence, the defective manufacturing processes which made the elements distribute inhomogeneous is concluded as the reason of the super hard end mill failure.

Influencing the Properties of the Generated Surface by Adjusted Rake and Clearance Angles in Side Milling of Aluminum Matrix Composites with MCD-Tipped Tools

The application of aluminum matrix composites (AMCs) allows the reduction of moving loads for increased efficiency in modern technical systems. However, the presence of reinforcing particles leads to challenges in machining of AMCs, typically requiring diamond cutting materials. Single-edged MCD-tipped tools are used to investigate the influence of different clearance and rake angles on the resulting surface properties in milling, while the cutting parameters are kept constant. The specimens are manufactured from an aluminum wrought alloy comparable to EN AW-2017, reinforced with 10 vol.% of SiC particles. The surface properties are evaluated considering the surface structure, the residual stress state, and the microstructure of the surface layer. A clearance angle of the minor cutting edge of about 3° on average leads to the lowest Rz values and a reduced fluctuation of surface roughness values. Using a tool with a positive rake angle of 5° entails the highest absolute values of the compressive residual stresses and an increase compared to the initial state of up to about 290%. The results contribute to an understanding of the relations between tool geometry and the generated surface properties required for a targeted enhancement of the functional performance when machining AMCs.

Experimental investigation of burr reduction during EDM end-milling hybrid process

Burrs are always generated during the end-milling process of ductile materials and have become a common challenge because a large plastic flow of the material is generated during cutting. In this research, a combination method of the end-milling and electrical discharged machining (EDM) process is proposed to suppress the generated burrs during machining; this process is called the EDM end-milling process. EDM end-milling was performed for side milling of AISI 1045 alloy steel (HRC = 28). The height of the generated burrs was measured and compared between ordinary end milling and EDM end-milling, and the experimental results indicate that the generated burrs are suppressed effectively by EDM end-milling owing to the effect of reduced plastic flow. The experimental results also indicate that the height of the generated burrs decreases when the capacitance values are increased during EDM end-milling. Furthermore, the results show that the height of the generated burrs remains unchanged by EDM end-milling when the axial depth of cut is increased.

Investigation the Optimization of Machining Parameters to Surface Roughness in Free Form Surface of Composite Material

The aim of this research is to investigation the optimization of the machining parameters (spindle speed, feed rate, depth of cut, diameter of cutter and number of flutes of cutter) of surface roughness for free-form surface of composite material (Aluminum 6061 reinforced boron carbide) by using HSS uncoated flat end mill cutters which are rare use of the free-form surface. Side milling (profile) is the method used in this study by CNC vertical milling machine. The purpose of using ANFIS to obtain the better prediction of surface roughness values and decreased of the error prediction value and get optimum machining parameters by using Taguchi method for the best surface roughness at spindle speed 4500 r.p.m, 920mm/rev feed rate, 0.6mm depth of cut, 10mm diameter, 2 flute.

Investigation on the vibration and machined surface quality in tilt side milling of thin-walled plates

Tilting milling tools to proper angles could help significantly suppress machining vibrations and enhance machined surface quality. The aim of this study is to investigate how the two fundamental variables, tool helix angle (β) and tilt angle (θ), could influence milling vibrations and machined surface topography when milling sidewall surfaces of thin-walled plates with solid end mills. A series of side milling tests were carried out at different tilt angles utilizing tools with different helix angles, during which the accelerations, instantaneous vibration displacements, cutting forces, machined surface roughness, and topographies of the workpiece were carefully measured. The results showed that the minimum machined surface roughness across the measured surface, Ra, was 0.37 μm when β = 40° and θ = 30°. In addition, optimal tilt angles for the lowest Ra on the machined surface with tools of different helix angles are in accordance with the optimal angles for the minimum absolute value of Z-axis force Fz, rather than ones for the weakest vibrations. This result indicates that, when milling sidewall surfaces of thin-walled plates, Ra is more highly dependent on the cutting force component along the lowest stiffness direction of plates than the vibration amplitudes. The results presented in this paper are useful insights for milling process parameter optimization to improve machined surface quality in milling sidewall surfaces of thin-walled components.

Application of RSM and ANN in Predicting Surface Roughness for Side Milling Process under Environmentally Friendly Cutting Fluid

The paper presents a potential study on prediction of surface roughness in side milling by optimization techniques approaches. Two methods, response surface methodology (RSM) and artificial neural networks (ANN) were used for optimized prediction. The model of surface roughness was expressed as the main parameter in side milling term of cutting speed, feed rate and axial depth of cut. Rotatable central composite design (RCCD) is employed in developing second-order response surface mathematical model. The ANN model using a multi-layer feed forward, back propagation and training function Levenberg-Marquardt (LM) algorithm with a single hidden layer. Vegetable oils have often been recommended as sustainable alternative cutting fluid since the ecological and health impacts in the use of mineral oil have been questioned and also the rising cost of mineral oil. The advantages of oxidative stability of coconut oil as vegetable oil were utilized in this study to investigate surface roughness of low carbon steel. The machining of ferrous alloy like steel is sometimes a difficult task. This study used uncoated tool because it is suitable when turning and milling alloy. Flood condition was selected because it has been proved effective at low cutting speed. The analysis predicted by RSM and ANN models resulted a good agreement between the experimental and predicted values. The results indicated that the ANN model predict with more accurate compared with the RSM model.

A sustainability comparison between drilling and milling for hole-enlargement in machining of hardened steels

Hole-making is one of the most important processes of metal shaping domain. Although, drilling is a commonly used approach to cut holes in metallic parts, the process cannot be completed with the cutting action of one drill bit if the work material is hard and diameter of the hole is large. Usually, a drill having diameter equal to the required diameter of the hole is utilized to enlarge a predrilled hole of a smaller diameter. In this work, we have investigated sustainability of using another method of enlarging a pre-drilled hole, namely side and end milling and compared it with the drilling-based approach. The work material used in the study is a high carbon steel, which is heat-treated to two distinct levels of surface hardness. Besides process type and work material hardness, the other two parameters tested in the investigation are cutting speed and depth of hole. A total of 16 experiments were performed to generate data regarding the sustainability measures, namely hole surface roughness, specific cutting energy and tool wear. Process choice (drilling or milling) for hole-enlargement was found to possess a significant effect on all the measured responses. Analyses carried out on the experimental data revealed that although the drilling-based option led to an immensely better surface finish, the milling-based option performed better with respect to the other measures of economic and environmental sustainability.

An experimental investigation on surface generation in ultraprecision machining of particle reinforced metal matrix composites

Ultraprecision machining of metal matrix composites (MMCs) is observed as a scientific challenge, due to their hard-to-machine property and often the poor surface finish. This paper presents an experimental investigation on surface generation in ultraprecision machining of Al/B4C/50p MMCs. The machining trials using straight flute polycrystalline diamond (PCD) tools are conducted on a high precision micro milling machine. Side milling is adopted under varied cutting conditions. Metrology assessments on the workpiece surface roughness, topography, texture and defects/features are undertaken using a ZYGO 3D surface profiler and a scanning electron microscope (SEM). Experimental results indicate that process parameters and their contributions play essential roles in the machining process. By applying the optimal process parameters, e.g. cutting speed of 188.496 m/min, feed rate of 10 μm/rev and axial depth of cut of 150 μm, a better surface generation with surface roughness Ra < 20 nm can be obtained in ultraprecision machining of Al/B4C/50p particulate MMCs.

Side Milling of Helical End Mill Oscillated in Axial Direction with Ultrasonic Vibration

This paper is focused on the cutting performance in the side milling of a small-size end mill with vibrations generated by an ultrasonic vibration spindle apparatus in the axial direction with a helix edge. In side milling with ultrasonic vibration in the rotational direction, the mean value of the cross-sectional chip area per cutting time decreases owing to the frequent repetition of the cutting and non-cutting phases. As a result, the cutting force decreases and provides an optimal cutting performance as compared to that in conventional side milling. First, the cross-sectional chip area is calculated using three-dimensional computer aided design (CAD) with its mean value relative to the cutting time. The ultrasonic vibration spindle apparatus is then attached to the machine spindle, and cutting tests are performed for conventional and ultrasonic vibration machining. Next, the flank wear, surface roughness, cutting force, and residual stress are measured. The results obtained from the cutting tests of the two machining methods are compared. The main results are as follows: (1) A comparison of the flank wears of conventional machining and ultrasonic vibration machining shows that the former is larger than the latter. The maximum flank wear increases as the cutting length increases for both the machining methods. (2) The maximum height of the machined surface in ultrasonic vibration machining is larger than that in conventional machining because of the marks caused by ultrasonic vibration. (3) The mean cross-sectional chip area relative to the cutting time decreases with ultrasonic vibration machining and the tool deformation decreases with a decrease in the mean cutting force relative to the cutting time. (4) With ultrasonic vibration machining, residual stress is generated on the machined surface not only in the feed direction but also in the axial direction because of the repetitive sliding actions in the axial direction of the flank of the cutting edge.

Longitudinal–torsional ultrasonic vibration-assisted side milling process

In this paper, a longitudinal–torsional ultrasonic vibration-assisted side milling is investigated. Different from the continuous cutting process in conventional side milling, the longitudinal–torsional ultrasonic vibration milling process is high-frequency intermittent. The intermittent cutting process is caused by the helical trajectory of the cutting edge. A mathematical model is established to simulate the trajectory and then the high-frequency intermittent cutting process is analyzed based on the model. Spindle speed, helix angle of milling tool, and ultrasonic vibration amplitudes are found to be the factors that are responsible for the ultrasonic cutting effect. When the spindle speed is 1500 r/min and the helical angle of milling tool is 30°, ultrasonic vibration milling experiments have shown that the cutting force can be reduced by 45.8% in the x direction at the most, 27.6% in the y direction, and 48% in the z direction compared to conventional milling. The experimental results also show that the decrement of the cutting force decreases along with the increasing of the cutting speed and helical angle of milling tool due to the decrease of the uncutting time. However, the increasing of the vibration amplitude can increase the decrement.

Influence of tool coating condition on side milling of amorphous laminated composite block

Iron-based amorphous metallic glass foil has a growing demand for the energy-efficient electric parts due to the excellent magnetic performances. The extreme mechanical properties in terms of high ultimate strength and high hardness make it to be a typical difficult-to-cut material. In addition, the form of ribbon foil formed by melt spinning technique can effectively reduce the eddy loss but also makes the conventional milling to be hardly performed. Amorphous laminated composite block consisted of metallic glass foils bonded by adhesive material provides an alternative structure. In this work, the investigations on machineability and tool wear were conducted using amorphous composite block consisted with iron-based metallic glass foil and acrylic adhesive bonding to advance the understanding of cutting performance. TiAlN and diamond coatings were used to reveal the wear mechanisms. Infrared camera was used to capture the cutting temperature of tool and produced chip as well as wear types were identified by SEM/EDS analysis. As a result, good surface quality of machined surface was obtained, associated with burrs generated on the margin along laminating direction. TiAlN coating exhibited a superior cutting performance and wear resistance compared with diamond-coating, which on the other hand showed a better chip removal process but was suffered from the thermo-chemical wear significantly.

Realization of ductile regime machining in micro-milling SiCp/Al composites and selection of cutting parameters

SiCp/Al composites are widely used owing to their outstanding performance. However, due to the existence of brittle SiC, surface defects caused by particle fracture damage the surface quality severely. Meanwhile, due to small cutting parameters during the micro-milling process, especially the undeformed chip thickness, which is mainly determined by the feed per tooth, the size effect of matrix also damages the surface quality. In this study, a method by realizing the ductile regime machining of the particle and diverting away the defects of particles and matrix is proposed to select the cutting parameters and improve the surface quality in micro-milling SiCp/Al composites. Suitable range of values of the feed per tooth for side milling and end milling are obtained by this method and validated by micro-experiments. The results show that the size effect of Al and removal ways of the SiC particles affect the machined surface simultaneously. By using suitable feed per tooth, weak size effect of Al and most of the particles’ ductile regime removing can be realized, leading to the generation of the best surface. Additionally, the machining effects of this method are more prominent in end milling than in side milling.

Effects of rotary ultrasonic elliptical machining for side milling on the surface integrity of Ti-6Al-4V

Ultrasonic elliptical vibration-assisted milling methods have recently attracted attention since they can be applied to difficult-to-cut materials. In this study, the effects of rotary ultrasonic elliptical machining parameters for side milling on Ti-6Al-4V titanium alloy machined surface integrity were investigated and compared with conventional machining for side milling. To determine the effects of rotary ultrasonic elliptical machining for side milling, roughness, topography, residual stress, microstructure, and microhardness of machined surface and subsurface were examined. Results show that rotary ultrasonic elliptical machining for side milling significantly improves the integrity of machined surfaces as a result of induced compressive residual stress, more pronounced plastic deformation, and work hardening of the machined surface. It was found that higher cutting speeds of up to 120 m/min and lower feed rates of approximately 0.02 mm/z achieve higher compressive residual stresses on the surface (− 221.21 MPa vs. 2.82 MPa), greater plastic deformation below the surface (up to 40 μm vs. less than 20 μm), and moderate surface work hardening (HV 425.85 vs. HV 414) using rotary ultrasonic elliptical machining for side milling compared to conventional machining for side milling. Finally, in relation to surface roughness (Ra), rotary ultrasonic elliptical machining for side milling was found to cause a slight deterioration of surface characteristics. The results of this study provide a better understanding of rotary ultrasonic elliptical machining for side milling of titanium alloy Ti-6Al-4V.

Influence of parameter matching on performance of high-speed rotary ultrasonic elliptical vibration-assisted machining for side milling of titanium alloys

In this paper, a novel high-speed rotary ultrasonic elliptical vibration-assisted machining method (HRUEM) for side milling is proposed to overcome problems associated with short tool life and low process efficiency during the titanium alloy finishing process. First, a theoretical model of separate-type HRUEM is presented and matching mechanisms and vibration period delay coefficient are fully analyzed. Feasibility experiments were performed used to compare the HRUEM method under different parameter matching conditions for titanium alloy milling with the conventional milling (CM) method. Then, a detailed analysis of process outputs including cutting force, chip formation, tool flank wear, surface topography, and roughness was performed. Based on the analytical model, micro-chips can be achieved with reasonable parameter matching using separate-type HRUEM. The process was further investigated experimentally to determine the tool life. Negative relief angle cutting introduced by HRUEM is found to be crucial and may prevent improvement in tool life. However, tool life of separate-type HRUEM with no negative relief angle cutting can be extended several times compared to CM. In addition, microscope observations of the machined surface revealed more uniform microstructures with HRUEM under reasonable parameter matching cutting conditions.