Milling Temperature Research Articles

Influence of the Cooling Temperature on the Surface Quality in Integrated Additive and Subtractive Manufacturing of Aluminum Alloy

The surface quality of parts processed by laser additive manufacturing, especially laser-based directed energy deposition (LDED), makes it difficult to meet actual use requirements. In addition, defects generated during the long-term additive manufacturing process need to be removed in time. Therefore, laser additive and subtractive manufacturing is of great significance for additive manufacturing. The main difference between laser additive-subtractive manufacturing and pure subtraction is that a cooling temperature is required due to the laser process. Therefore, this work studies the temperature variation regularity during LDED and the milling processes, as well as the surface roughness, cross-sectional microstructure, and tool wear under different cooling temperatures for milling. The results show that there is a “turning point temperature” in LDED, and the value of the turning point temperature gradually increases with heat accumulation, which affects the initial temperature of the subtractive manufacturing. When subtracting, a high initial temperature improves surface quality and reduces tool wear, but an excessively high temperature will cause the aluminum alloy to adhere to the tool. Then, the smear metal is difficult to effectively remove, deteriorates the milling quality, and aggravates tool wear. It is found that the higher the cooling temperature generated, the wider the thermally insulated shear band. The insulated shear band may affect the quality of the additive and subtractive manufacturing. Finally, it is determined that the milling temperature of aluminum alloy in this work condition is about 100 °C.

An integrated and intelligent milling temperature sensing tool holder with electromagnetic energy harvesting system

An integrated and intelligent milling temperature sensing tool holder with electromagnetic energy harvesting system

Study on the Properties of Sinusoidal Micro-Textured Ball End Milling Cutter for Milling Titanium Alloy

To improve the cutting performance when cutting hard alloys and achieve reasonable optimization of micro-texture parameters, this paper proposes a sinusoidal micro-textured tool, with four parameters set as micro-textured spacing, period, width, and amplitude. Establish three-dimensional models of non-micro-textured and micro-textured milling tools and simulate the milling process using finite element simulation. Study the effects of milling force and milling temperature on tool performance. Prepare micro-textured milling tools for orthogonal experiments, analyse the effects of milling force and the surface roughness of a titanium alloy workpiece, and study the impact of different micro-textured parameters on milling tool performance. Obtain the parameters that have the greatest impact on milling tool performance, and then use genetic algorithm to optimize three sets of parameter combinations. Use the optimized parameters to prepare milling tools for comparative experiments, and then determine the optimal parameter combination. The research results indicate that micro-textured tools can effectively improve the milling performance of the tool, and the spacing between sinusoidal micro-textures has the greatest effect on improving the milling performance of the tool. When the period of sinusoidal micro-texture is 2.87 and the amplitude is 25.13 μm, width is 79.89 μm, and spacing is 134.54 μm, the milling performance of the tool is optimal.

Comprehensive analysis of cutting temperature, tool wear, surface integrity and tribological properties in sustainable milling of Ti6Al4V alloy: LN2, nanofluid and hybrid machining

Despite being expensive and difficult to process, the Ti6Al4V alloy is a vital component for crucial industries. To improve its machinability and accomplish sustainable production, environmentally friendly cooling and lubricating agencies are used. Studies on the machinability of the alloy are still necessary because of its unique features and significance in vital industries like aerospace, defense, and medicine. Therefore, this investigation focuses on tool wear, temperature, and surface integrity for sustainable milling Ti6Al4V under various machining environments, i.e., dry, pure-MQL, LN2, hBN, CuO-doped nanofluids, and hybrid methods. The produced nanofluids' thermophysical and rheological characteristics were examined in the study's initial phase. Because of the results from the first stage, machining performance indicators were assessed in the subsequent milling experiments. As a result, CuO-doped nanofluids gave improved results in terms of viscosity and pH. The best results obtained in the LN2 + CuO hybrid cooling lubrication environment in important machinability outcomes such as tool wear and surface integrity were attributed to the rheological properties of CuO-doped nanofluid and its harmonious cooperation with LN2-cryogenic cooling.

Investigating the Impact of Robotic Milling Parameters on the Surface Roughness of Al-Alloy Fabricated by Wire Arc Additive Manufacturing

This paper takes the single-wall wall manufactured by wire arc additive manufacturing (WAAM) as the research object and compares it with the as-cast aluminum alloy with the same series. By using feed rate, cutting depth, spindle speed, etc., as single or compound parameters, the machinability of the sample is analyzed. The results indicate that the influence of varying parameters on the as-deposited aluminum alloy follows the order of feed rate > cutting depth > spindle speed. As the feed rate increases, the surface roughness initially decreases and then increases, with the optimal surface quality achieved at 12 mm/s (with a surface roughness of 2.013 μm). Different from the as-deposited alloy, the influence of the parameters on the as-cast alloys follows the order of spindle speed > cutting depth > feed rate. The experiments reveal that, for both as-deposited and as-cast states, the trends of the impact of cutting depth and spindle speed on surface quality are consistent. However, at low feed rates (2–12 mm/s), for as-deposited states, the surface quality of as-deposited samples becomes smoother as the feed rate increases (contrary to common knowledge). This result can be attributed to the elevated milling temperature, which softens the material, making it easier to remove and reducing the surface roughness.

Design and Simulation of Torque Control for Hot Rolling Steel Mill

Lateral movement of a strip in the hot rolling process is an important unsolved technical problem. To minimize the strip thickness variations, the state space model formulation is usually used. It results in reducing productivity and, in the extreme case, strip tearing during tailing out at the finishing mill. This movement is caused by various asymmetric factors such as mechanical asymmetry of the mill and different temperatures along the strip width direction. Furthermore, the difference in the temperature and the thickness of steel strip resulting in deformation of the steel, which affects the bending torque of the steel strip. This study aims to understand the influences of these various factors on lateral movement. In order to reduce the lateral movement and the disturbance terms, that act on uncertain inter-connected systems, a new control approach, based on a combination of Integral Sliding Mode Control (ISMC) and Linear Matrix Inequalities (LMI) technique, is proposed. Simulation results of hot rolling system with three interconnected systems are presented to validate the new controller performance.

Understanding the effects of cutting conditions on vibrations, surface integrity, machining temperature and tool wear mechanisms in end milling of AISI D2 Steel

The study explores vibrations, and thermal and tool wear (TW) mechanisms during dry end milling of AISI D2 steel employing two-, four-, and six- flute designs of TiAlN-PVD coated carbide end mill cutting tools. Because of multi-physics interactions in machining zone, supervised machine learning is used to understand TW, machining vibrations (MV), surface roughness (Ra) and the temperature of machining zone (TMZ), and to correlate the surface characteristics. A dedicated full factorial design of experiments campaign involving flutes (Fn), feed rate (Fr), and depth of cut (Doc) as variables is carried out to learn tool-workpiece interfacial characteristics. Results revealed that MV, Ra, TMZ and TW improved 57.82 %, 87.11 %, 79.22 % and 79.40 %, respectively at Fn = 6, Fr = 300 mm/min and Doc = 0.5 mm. Supervised machine learning (neural networks) and non-dominated sorting genetic algorithm (NSGA-II) based results showed reduction in vibrations by 89.84 %, Ra 97.39 %, tool-workpiece interaction temperature by 56.86 % and TW by 57.07 % by understanding mechanistic correlations of machining parameters with performance metrics.

Coupling pulsed magnetic treatment coated WC-12Co cemented carbide and magnetofluid to enhance milling performance of TC4 alloy

To explore an eco-friendly approach to improve the milling performance of TC4 (Ti-6Al-4 V) alloy, pulsed magnetic field treatment and magnetofluid are simultaneously applied to the NbN-coated cemented carbide (WC–12Co) milling tools. To evaluate the coupling effect of pulsed magnetic field treatment with magnetofluid, milling experiments of TC4 were conducted under cutting fluid and magnetofluid lubrication, respectively. The milling force, tool wear, and workpiece surface quality of magnetic field treated tools were compared with those of untreated tools. When the cutting fluid was lubricated, the magnetic field treatment reduced the feed force by 8.8 %. In contrast, the magnetic field treatment reduced the feed force by 20.7 % when the magnetofluid was lubricated, which reduced tool wear and also weakened coating flaking. The coupling of the magnetic field treatment and the magnetofluid significantly improved the milling performance of the tool, reducing surface roughness by 40.9 % compared to the untreated tool with cutting fluid lubrication. The enhanced milling performance mainly results from the coupling effect of magnetic field treatment and magnetofluid, which has a strong magnetic response to the treated tool and the magnetofluid was attracted to the magnetized tool, enhancing the lubrication of the contact area. In addition, the enhanced mechanical properties (8.2 % increase in hardness, 13.1 % decrease in elastic modulus, and 4.5 % increase in thermal conductivity) resulting from the pulsed magnetic field treatment reduces the milling temperature (11.7 °C) also contribute to the enhanced milling performance.

Research on the Milling Performance of Micro-Groove Ball End Mills for Titanium Alloys

Titanium alloys are widely used in various fields, but milling titanium alloy materials often leads to problems such as high milling forces, increased milling temperatures, and chip adhesion. Thus, the machinability of titanium alloys faces challenges. To improve the milling performance of titanium alloy materials, this study analyzes the effective working area on the surface of the milling cutter through mathematical calculations. We design micro-grooves in this area to utilize their friction-reducing and wear-resisting properties to alleviate the aforementioned issues. The effective working area of the ball end milling cutter’s cutting edge is calculated based on the amount of milling and the installation position between the milling cutter and the workpiece. By observing the surface structure of seashells, micro-grooves are proposed and designed to be applied in the working area of the milling cutter surface. The impact of the micro-groove area on the milling cutter surface and spindle speed on milling performance is discussed based on milling simulation and experimental tests. Experimental results show that the cutting force, milling temperature, and chip resistance to adhesion produced by micro-groove milling cutters are superior to conventional milling cutters. Milling cutters with three micro-grooves perform best at different spindle speeds. This is because the presence of micro-grooves on the surface of the milling cutter improves the friction state, promoting a reduction in milling force, while the micro-grooves also serve as storage containers for chips, alleviating the phenomenon of chip softening and adhesion to the cutter. When conducting cutting tests with a milling cutter that has three micro-grooves, the milling force is reduced by 10% to 30%, the milling temperature drops by 10% to 20%, and the surface roughness decreases by 8% to 12%.

Fabrication of FeP2/C/CNTs@3D interconnected graphene aerogel composite for lithium-ion battery anodes and the electrochemical performance evaluation using machine learning

Featuring low cost and high theoretical capacity, phosphorus-rich iron diphosphides (FeP2) have emerged as excellent anode candidates for lithium-ion batteries. However, the typical chemical synthses involving high temperatures and toxic gases have restricted the mass production of FeP2. We now report a FeP2/C/CNTs@3D interconnected graphene aerogel composite synthesized by ball milling and low temperature heat treatment. Because of the unique microstructure and synergistic effect between well-dispersed FeP2 particles and graphene aerogel, the as-prepared FeP2/C/CNTs@GA-2.5% displays excellent lithium storage performance in terms of reversible capacity (886 mA h g−1 at 0.1 A g−1), cycling stability (476 mA h g−1 at 2 A g−1 even after 1000 cycles), and rate capability (685 mA h g−1 at 5 A g−1). Machine learning methods (decision tree and random forest algorithms) prove effective in evaluating and predicting electrochemical performance of the electrode materials.

Multi-point thermometry tool and in-situ measurement of temperature fields

In-situ real-time measurement of instantaneous milling temperature distribution is a key issue to realize efficient machining. For the foregoing reasons, the milling model of Inconel 718 was established, and the cloud diagram of tool temperature distribution during milling was obtained. A multi-point temperature measurement tool for milling temperature with an integrated thin-film temperature sensor was designed. The real-time temperature distribution of the tool during milling was obtained from 27 sets of milling tests. The impact of each milling parameter on the milling temperature was analyzed by ANOVA.

Evaluation of Cutting Temperature and Optimization in Milling of GGG60 Cast Iron

Spheroidal graphite cast irons have increased ductility, tensile strength, and toughness compared to other cast irons. Additionally, it can be mentioned that choosing spheroidal graphite cast iron over steel material has a better machining feature. In this study, Face milling operations were carried out using GGG60 material and different inserts, feed, and depth of cut. The Taguchi method was used for the experimental design, and 27 experiments were carried out. During the experiments, a thermal camera measured the temperature from the cutting zone. Experimental results were evaluated with analysis of variance and graphics, and cutting parameters were optimized. As a result of the optimization, optimum parameters for minimum temperature, TiAlN coated insert, 300 m/min cutting speed, 0.30 mm/tooth feed rate, and 0.5 mm depth of cut were found. According to the results obtained from the study, the most influential parameter affecting the temperature was the cutting speed. In addition, the TiAlN-coated insert has been observed as the most suitable coating type for minimum temperature.

A novel synthesis from instability difference between SiC 3-C and 6-H crystal to form nanoparticles stems by alkali solution and its degrading various environmental pollutants

In this paper, the nano silicon carbide with different sizes was prepared without hydrofluoric acid by using simple milling and related low temperature etching process in normal pressure. Also, it was the first time verified that 3-C dominated crystalline form of polycrystalline silicon carbide is etched, leaving the 6-H silicon carbide crystalline form by the Raman spectra and HAADF-STEM (high-angle-annular dark-field scanning transmission electron microscopy) imaging that. The application of the alkali etching technique could precise control the partial structural transformation of silicon carbide crystals to a certain extent, which further expands the traditional crystal structure transformation process. In addition, this paper demonstrates the silicon carbide composites in photocatalytic removal of various organic pollutants from aqueous solutions. In the photo degradation of MB (Methylene Blue), the removal rate of the modified silicon carbide shown ten times as much as the commercial silicon carbide. The 1-h degradation efficiency was significantly higher in the 50 μL H2O2 system (100.0%, 86.8% and 89.9% removal of MB, Rhodamine B, Methyl Orange and Tetracycline hydrochloride, respectively). Furthermore, the unit spin concentrations of vacancy defects, superoxide radicals and hydroxyl radicals were quantitatively analyzed. The vacancy defects of the etched material were 1000 times higher than before, and the modified silicon carbide had higher transmittance to infrared and visible light. It strongly absorbs ultraviolet light. Conversely, the research on micron-sized silicon carbide loaded with Ag and Pt atoms found that it had a nitrogen fixation effect during the warming up process, in a nitrogen atmosphere.

Optimizing milling parameters based on full factorial experiment and backpropagation artificial neural network of lamina milling temperature prediction model.

Milling operations of laminae in spinal surgery generate high temperatures, which can lead to thermal injury and osteonecrosis and affect the biomechanical effects of implants, ultimately leading to surgical failure. In this paper, a backpropagation artificial neural network (Bp-ANN) temperature prediction model was developed based on full factorial experimental data of laminae milling to optimize the milling motion parameters and to improve the safety of robot-assisted spine surgery. A full factorial experiment design were used to analyze the parameters affecting the milling temperature of laminae. The experimental matrixes were established by collecting the corresponding cutter temperature Tc and bone surface temperature Tb for the milling depth, feed speed and different bone densities. The Bp-ANN lamina milling temperature prediction model was constructed from experiment data. Increasing milling depth increases bone surface and cutter temperature. Increasing feed speed had little effect on cutter temperature, but decreased bone surface temperature. Increasing bone density of laminae increased cutter temperature. The Bp-ANN temperature prediction model had best training results in the 10th epoch, and there is no overfitting (training set R= 0.99661, validation set R= 0.85003, testing set R= 0.90421, all temperature data set R= 0.93807). The goodness of fit R of Bp-ANN was close to 1, indicating that the predicted temperature was in good agreement with the experiment measurements. This study can help spinal surgery-assisted robot to select appropriate motion parameters at different density bones to improve lamina milling safety.

Thermal stability of Ni3Al microstructure and microhardness after spark plasma sintering

The effect of high-temperature annealing on the structural-phase state and microhardness of Ni3Al samples obtained by spark plasma sintering after high-energy ball milling has been studied. Using X-ray diffraction analysis, scanning and transmission electron microscopy, a comparative study of the features of the structural-phase state of Ni3Al samples depending on the duration of preliminary high-energy ball milling and annealing temperature was carried out. Temperatures have been identified that ensure simultaneous grain growth at a high density of nuclei, which contributes to the formation of a fine-grained structural state. Depending on the state of the material, the corresponding microhardness values have been determined. The influence of the annealing temperature on the strengthening mechanisms has been analyzed.

Milling machinability analysis of GW63K rare-earth magnesium alloys based on the concept of clean cutting

GW63K rare-earth magnesium (Mg-RE) alloys have been widely used in various advanced industries for their excellent mechanical properties. However, the machinability of GW63K alloys under clean cutting conditions still needs to be better understood. The novelty of this paper lies in addressing the influences of varying cutting parameters on the milling responses of GW63K Mg-RE alloys as well as the underlying mechanisms. A full-factorial design of experiments was conducted under dry cutting and minimum quantity lubrication (MQL) conditions. A three-tooth milling cutter with a diameter of 12 mm was used during the investigation. The critical milling outputs involving cutting forces, machining temperatures, and surface quality attributes were carefully analyzed. The results indicate that the cutting force highly depends on the feed per tooth, and the cutting temperature is raised with the increased cutting speed and feed per tooth. The MQL is found capable of reducing the milling temperature by 10.8 °C on average compared with dry cutting. The MQL shows benefits in improving the cutting performances of tools and surface quality of Mg-RE alloys by reducing the tool-workpiece friction coefficient and enhancing the heat dissipation conditions of the chip contact surface. In addition, lower feed per tooth and higher cutting speeds under MQL conditions are suggested for the milling of Mg-RE alloys while ensuring processing efficiency.

Assessment of Lubrication Property and Machining Performance of Nanofluid Composite Electrostatic Spraying (NCES) Using Different Types of Vegetable Oils as Base Fluids of External Fluid

The current study of minimum quantity lubrication (MQL) concentrates on its performance improvement. By contrast with nanofluid MQL and electrostatic atomization (EA), the proposed nanofluid composite electrostatic spraying (NCES) can enhance the performance of MQL more comprehensively. However, it is largely influenced by the base fluid of external fluid. In this paper, the lubrication property and machining performance of NCES with different types of vegetable oils (castor, palm, soybean, rapeseed, and LB2000 oil) as the base fluids of external fluid were compared and evaluated by friction and milling tests under different flow ratios of external and internal fluids. The spraying current and electrowetting angle were tested to analyze the influence of vegetable oil type as the base fluid of external fluid on NCES performances. The friction test results show that relative to NCES with other vegetable oils as the base fluids of external fluid, NCES with LB2000 as the base fluid of external fluid reduced the friction coefficient and wear loss by 9.4%-27.7% and 7.6%-26.5%, respectively. The milling test results display that the milling force and milling temperature for NCES with LB2000 as the base fluid of external fluid were 1.4%-13.2% and 3.6%-11.2% lower than those for NCES with other vegetable oils as the base fluids of external fluid, respectively. When LB2000/multi-walled carbon nanotube (MWCNT) water-based nanofluid was used as the external/internal fluid and the flow ratio of external and internal fluids was 2:1, NCES showed the best milling performance. This study provides theoretical and technical support for the selection of the base fluid of NCES external fluid.

Geometric Structures for Sialon Ceramic Solid End Mills and Its Performance in High-Speed Milling of Nickel-Based Superalloys

Sialon ceramic tool material has become one of the most ideal materials for the high-speed cutting of superalloy materials. However, studies on the geometric structure of sialon ceramic solid end mill is lacking at the present. In this work, the geometric structure of sialon ceramic end mills was designed for difficult-to-machine nickel-based superalloy materials. The cutting force and heat, flank wear and machined surface quality were analyzed to study the effect of the main parameters on tool performance. The results showed that the end mill experienced severe flank wear and chipping, which were the leading cause of its failure during high-speed cutting. The cutting force and temperature decreased gradually with the increase in the helix angle. With the increase in the rake angle, the flank wear and the quality of the machined surface of the specimen first decreased and then increased. With the increase in the relief angle, the cutting temperature of the ceramic end mill gradually decreased, and the cutting force and the machined surface roughness showed an initial decrease and then increased. When the helix angle, rake angle and relief angle were 35°, −15° and 12°, respectively, the sialon ceramic end mill exhibited the best cutting performance and obtained better machined surface quality in the nickel-based superalloys.

Investigation and production of non-cytotoxic TixNbxSn (x = 5,10,15,20) alloys by high-energy mechanical milling with antibacterial activity

In this research, TixNbxSn (x = 5, 10, 15, 20 wt%) alloys were produced by high-energy mechanical alloying, and their potential applications as biomaterial were investigated through the microstructural characterizations (via XRD, SEM, and EDS analyses), mechanical tests (via hardness and elastic modulus tests), and biological studies (via antibacterial and cytotoxic tests). The alloying studies were carried out at room temperature in a high-energy ball milling for 8 h followed by a consolidation using a uniaxial pressing and 2 h pressureless sintering at 1150 °C. The XRD and EDS analyses showed that α-Ti, β-Ti, and TiC phases were present in the microstructure after sintering at high-temperature. Hardness tests revealed a wide range of values between 384 and 723 HV depending on the alloy compositions. That is, the volume fraction of TiC phase formed during processing and the ratio of α-Ti/β-Ti phases appear to control the hardness of the alloys. The elastic modulus was determined ranging from 70 to 103 GPa as a function of compositions with Ti15Nb15Sn alloy having the closest elastic modulus to the bone. The biological investigations revealed that TiNbSn alloys exhibited antibacterial properties against Staphylococcus aureus (S. aureus) and were not cytotoxic to healthy cells, regardless of their compositions. Furthermore, the findings indicated that when the cells were subjected to various dilutions of alloy extracts, there was a noticeable enhancement in both cell proliferation and viability. These findings have the potential to pave the way for novel approaches in the creation of TiNbSn alloys as biomaterials.

Cutting performance of binderless nano-polycrystalline cBN and PcBN milling tools for high-speed milling of hardened steel

Since difficult-to-machine materials are widely used in high-end equipment such as aerospace and marine components as well as precision molds, the development of high-performance cubic boron nitride (cBN) tools has been an important area of research. In this paper, we evaluate a new type of finer-grained, binderless end mill (binderless nano-polycrystalline cBN, BNNC) by comparing it to polycrystalline cBN (PcBN) end mills for high-speed machining of hardened steel. First, the process of tool preparation based on the above novel cBN is described and high-speed milling experiments were designed. Then, the cutting performance of the BNNC and PcBN tools during high-speed milling is analyzed and compared in four aspects: the cutting force coefficients, the friction coefficient of the rake face, the milling temperature and the tool wear. In addition, the wear mechanism of the two types of end mills was analyzed by energy dispersive X-ray (EDX). Afterwards, the trend of cutting temperature was further investigated by 2D finite element simulation. Finally, grey correlation analysis was applied to describe the correlation between the above factors and tool wear. This study shows that compared with PcBN end mills, BNNC end mills have longer tool life under the same cutting condition and are more reliable at high temperatures, which exhibit great application potential.