Milling Behavior Research Articles

Wear behavior of all-ceramic micro end mills in micro milling of PMMA

Micro milling is a state-of-the-art micro manufacturing method employed, for instance, in the context of prototyping applications. Due to the high specific cutting forces and small tool diameters inherent to micro milling, tool wear represents a significant challenge for the fabrication of large, high-quality structures. In conventional cutting applications, ceramic tool substrates have been demonstrated to exhibit greater wear resistance than cemented carbides. In the case of micro milling of polymethylmethacrylate (PMMA), all-ceramic micro end mills made from zirconia (Y-TZP) have been observed to exhibit less tool wear than common cemented carbide micro end mills. In previous experiments, these tools exhibited a feed per tooth-dependent wear behavior, regardless of the spindle speed employed. The objective of this study was to investigate the wear behavior of the all-ceramic micro end mills at higher feeds per tooth (up to 7.5 µm) and spindle speeds (up to 110,000 rpm) in PMMA. The objective was to fully characterize the interactions between the all-ceramic micro end mills and the milling parameters for this thermoplastic workpiece material. The wear at the cutting edge was quantified by analyzing the topography with an atomic force microscope, and the results were correlated with the cutting forces and process outcomes. The results were found to be highly sensitive to the spindle speed used, with higher speeds leading to higher temperatures in the cutting zone and thus softening of the PMMA material. In general, micro milling parameters of 110,000 rpm and a feed per tooth of 5 µm resulted in significantly reduced tool wear with no adverse effect on surface quality when micro milling PMMA with all-ceramic micro end mills.

Experimental validation of the amplitude ratio as a metric for milling stability identification

This paper presents the experimental validation of the amplitude ratio, a metric for milling stability identification. The amplitude ratio quantifies the severity of chatter by comparing the amplitude of the expected frequency content of a milling signal (i.e., tooth passing frequency, runout frequency, and harmonics) to the amplitude of the chatter frequency, if present. Through multiple iterations of a milling time domain simulation, the amplitude ratio diagram, which characterizes stable and unstable milling behavior over a range of spindle speeds and axial depths of cut, may be generated. In this paper, a comparison of the simulated and measured amplitude ratios for a series of milling test cuts is presented. It is shown that the amplitude ratio is suitable for identifying milling stability in both simulations and experiments. Additionally, it is shown that through judicious selection of low-cost sensors, implementation of the amplitude ratio is cost efficient. Direct comparison of the simulated and measured amplitude ratios demonstrates the effectiveness of the approach.

Experimental Study on Dry Milling of Stir-Casted and Heat-Treated Mg-Gd-Y-Er Alloy Using TOPSIS

This study examines the dry milling process of a rare-earth-based magnesium alloy, emphasizing the optimization of the milling parameters and their impact on the surface quality, cutting forces, and the rate of material removal. The objective is to improve our comprehension of the milling behavior of the Mg-Gd-Y-Er alloy. The Taguchi technique is adopted to formulate the experimental design. This study methodically investigates the influence of heat treatment (T4 and T6) on milling performance, and the effects of speed, feed rate, and depth of cut. The output variables considered for this investigation are the surface roughness (Ra, Rz, Sa, and Sz), material removal rate (MRR), and cutting force. To optimize the milling parameters and achieve superior outcomes, the multi-objective optimization technique TOPSIS is used. At a feed rate of 150 mm/min, a spindle speed of 1500 rpm, and a depth of cut of 1 mm, the T4-treated sample exhibits a minimum surface roughness value of 0.0305 µm. The highest resultant force values of 96.4416 N and 176.1070 N for 200 °C and 225 °C T6-treated alloys are obtained by combining process parameters such as a spindle speed of 1500 rpm, a feed rate of 50 mm/min, and a depth of cut of 1.5 mm. Furthermore, the maximum closeness coefficient value is achieved by combining a spindle speed of 1000 to 1500 rpm, a feed rate of 150 mm/min, and a depth of cut of 0.5 mm to 1 mm. The closeness coefficient value is significantly influenced by the most significant process parameters, as indicated by the ANOVA results.

Role of Li and Sc Additions and Machining Conditions on Cutting Forces on Milling Behavior of A7075-Based Alloys

Role of Li and Sc Additions and Machining Conditions on Cutting Forces on Milling Behavior of A7075-Based Alloys

Study on milling behavior of TiAlN coated tool with variable distribution density micro-texture

Considering that after milling titanium alloy with a ball-end milling cutter, the wear degree of different areas of the rake face is different, which indicates that the tool-chip contact conditions in this area are different, and then the micro-texture action mode is different. To improve the effect of micro-texture, this paper establishes a mathematical distribution model of variable distribution density micro-texture based on the two-zone method, builds a variable distribution density micro-texture ball-end milling titanium alloy test platform, studies the influence of variable density micro-texture parameters on tool milling behavior, and optimizes the parameters based on the improved particle swarm optimization algorithm. The results show that the micro-texture with variable distribution density has a positive effect on the milling behavior of the tool. The micro-texture parameters of the stickiness area have the greatest influence on the milling behavior of the tool. A texture parameter is optimized, and the overall milling behavior of the variable density micro-texture TiAlN coated milling cutter is optimal. This study provides a theoretical basis for the design and preparation of variable distribution density micro-textured tools. Highlights Based on the two-zone method, the mathematical distribution model of the variable distribution density micro-texture of the rake face of the tool is constructed. The influence mechanism of micro-texture parameters on the milling behavior of a ball-end milling cutter is explored. The multi-objective optimization of the variable density micro-texture parameters was carried out, and the optimal parameter combination was obtained. It is verified that the variable distribution density of the micro-texture has a positive effect on the cutting performance of the tool.

Effects of build orientation and hatch spacing on high-speed milling behavior of L-PBF 316L stainless steel

Abstract Due to the philosophy of the process, the surface roughness is usually high for the parts produced with laser powder bed fusion (L-PBF) additive manufacturing (AM). Parts produced by this method need surface quality improvement processes for many applications. One of the methods used for this purpose is high speed machining (HSM). HSM is a modern manufacturing technique that offers several benefits, including improved productivity, enhanced product quality, and reduced production costs. In addition, HSM can improve the quality of finished products by reducing machining errors. In this study, samples produced with 316L powder in size of 10 × 10 × 5 mm using three different hatch spacings (60, 70, 80 µm) and building orientations (0°, 45°, 90°) were produced by L-PBF method, and HSM process was applied to these samples. In this context, the present study aimed to investigate the effects of porosity, microstructure and microhardness properties of 316L samples produced by L-PBF method using different hatch spacings and build orientations on cutting forces, surface roughness and burr formation in HSM. When the numerical values of the cutting forces were analyzed in both x and y directions, it was observed that the greatest cutting force occurred in the x direction. While the Fx force ranged from 6.23 to 9.35 N, the Fy force ranged from 4.88 to 8.27 N. It has been determined that as the build orientation increases at the same hatch spacing value, the cutting forces increase due to the increased porosity ratio.

Uniform-Density Micro-Textured Ball-End Milling Cutter Model Based on Fractal and Uniform Distribution Theory

At present, for micro-textured tools, the determination of the micro-texture placement area depends on the derivation of the cutting geometric model. The micro-texture distribution form applies geometric methods, and the research methods and accuracy are limited. Therefore, in this paper, the ball-end milling cutter is taken as the research object. Based on fractal theory, the morphology of the tool before and after wear is compared to determine the tool–chip contact area. The uniform-density micro-texture distribution model is established using the uniform distribution point theorem, and the synergistic mechanism of the edge and the micro-texture is revealed. The strength of the micro-textured tool with uniform density under the action of the edge is studied by simulation. Finally, the determination of the tool–chip contact area and the establishment of a uniform-density micro-texture model is realized. It is proved that the synergistic effect of the cutting edge and the micro-texture has a positive effect on the milling behavior of the tool. When comparing the non-edge and non-texture tools with the cutting-edge tools, the maximum strain and stress of the cutting-edge micro-textured tools increased by 12% and 30%, and 30% and 20%, respectively, without affecting the normal use of the tool. This research provides a new method for the design of micro-textured tools.

Study on the milling performance of ball-end milling cutter under the combined action of micro-texture of rake and flank face

PurposeIt was verified that the micro-texture in the front and back of the tool at the same time had a positive effect on improving the milling behavior and surface quality of the tool. The purpose of this study is to explore the rationality of simultaneous placement of micro-textures on the front and rear surfaces of ball-end milling cutters, analyze the influence of micro-texture parameters on tool milling behavior and workpiece surface quality, reveal its internal mechanism, and obtain the best micro-texture parameters by optimization.Design/methodology/approachFirst, the mechanism of micro-texture is studied based on the energy loss model. Second, the orthogonal experiment is designed to analyze the influence of micro-texture parameters on tool milling behavior and reveal its mechanism by combining simulation technology and cutting experiment. Finally, the parameters are optimized based on the artificial bee colony algorithm.FindingsThe results show that the simultaneous placement of micro-texture on the rake face and flank face of the tool has a positive effect on improving the milling behavior and surface quality of the tool. Taking milling force, tool wear and surface roughness as the evaluation criteria, the optimal parameter combination is obtained: the rake face micro-texture diameter is 50 µm, the distance from the micro-texture is 200 µm and the distance from the cutting edge is 110 µm; the diameter of the micro-textured flank is 40 µm, the distance from the micro-texture is 170 µm and the distance from the cutting edge is 130 µm.Originality/valueTaking milling force, tool wear and surface roughness as the evaluation criteria, the optimal parameter combination is obtained: the rake face micro-texture diameter is 50 µm, the distance from the micro-texture is 200 µm and the distance from the cutting edge is 110 µm; the diameter of the micro-textured flank is 40 µm, the distance from the micro-texture is 170 µm and the distance from the cutting edge is 130 µm, which provides theoretical support for the further study of the micro-textured tool.Peer reviewThe peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-01-2023-0022/

Understanding the effect of metamictization on the efficiency of zircon milling

Six commercially available zircon sands were characterised by XRD, SEM, BET and helium pycnometry to determine their degree of metamictization. These sands were categorized into pairs denoted as high, medium or low levels of metamictization. The six samples were subsequently dry milled under identical conditions and their milling behaviour was tracked by measuring the particle size distribution at regular intervals. Samples with low levels of metamictization were found to achieve a marginally smaller particle size than samples with high levels of metamictization after prolonged milling. This was attributed to two potential mechanisms during breakdown – brittle fracture in the former due to retained hardness, in comparison to a more ductile resistance to fracture in the latter due to reduced hardness. However, no clear trend between specific metamictization characteristics and milling behaviour was found. The results reveal a poorer overall milling efficiency for high metamict samples, which has implications such as increased energy costs, poor quality product and a need for further processing of samples exhibiting high levels of metamictization. This study creates a novel link between the milling behaviour of zircon and its level of metamictization. The knowledge gained holds strong importance for industrial entities wishing to carry out and maintain an efficient milling process, with feed material quality likely to become more variable in future years.

Preparation of two-dimensional manganese dioxide nanosheets by stirred media milling and its application as supercapacitor electrode materials

A novel top-down approach for ultrathin two-dimensional (2D) MnO2 nanosheets preparation in stirred media mill as an active electrode material for supercapacitors is reported in this work. The milling behavior with time was analyzed, followed by the electrochemical analysis of a milled sample. The XRD peak shows that crystallinity of prepared 2D MnO2 nanosheets decreased. Scanning Electron Microscopy (SEM) depicted a plate-like structure of a few hundred-nanometer lateral dimension. High-Resolution Transmission Electron Microscopy (HR-TEM) and Atomic Force Microscopy (AFM) further confirmed the formation of 2D MnO2 nanosheets. The cyclic voltammetry gave the specific capacitance of 356.11 F/g.

Vibration Energy Coupling Behavior of Rolling Mills under Double Disturbance Conditions

The operation of the world’s first multimode continuous casting and rolling F3 (3rd finishing mill stand) finishing mill was hampered by frequent vibrations. Mill vibrations were found to be caused by the transmission and coupling of vibration energy flow. In this study, an overall finite element model of the F3 stand is established based on the structural sound intensity method and harmonic response analysis method, and then, the intrinsic energy flow modes and energy flow harmonic response of the F3 stand are obtained. Further, the effects of the steady-state rolling force variation, preload torque variation, rolling force fluctuation, torque fluctuation, and its phase angle difference on the vibration energy flow of the mill are analyzed. Finally, the effects of the mill damping ratio, strip width, and strip modulus on the vibration energy flow under double dynamic load are discussed to reveal the inherent characteristics of the mill vibration energy flow. The results show that the vibration energy flow of the mill increases with the increase of strip modulus, rolling force, and moment fluctuation; the phase angle difference of rolling moment shows a “V” trend change on the vibration energy flow; the change of strip width has a greater effect on the vibration energy flow of the vertical system; and for the damping ratio of 0.01–0.1, the reduction of the vibration energy flow at all excitation frequencies is obvious.

Effect of reinforcement types on the ball milling behavior and mechanical properties of 2024Al matrix composites

In this paper, 2024 Al matrix composites reinforced by nanocrystalline high-entropy alloy particles (NC-HEAp), SiC particles, and coarse-grained high-entropy alloy particles (CG-HEAp) were fabricated via powder metallurgy, and a comparative study of different reinforcements was deeply conducted. The results showed that reinforcement types significantly influenced the morphology of composite powders, and the grain size and interfacial condition of composites. After ball milling, irregular granular NC-HEA-Al and SiC–Al composite powders were produced while the CG-HEA-Al composite powders exhibited flake shapes, and particle size of NC-HEAp sharply decreased and was significantly smaller than the other two reinforcements. The Cu-rich diffusion layer, a high dislocation density, and a thin oxide layer were formed in the interfaces of NC-HEA-Al, SiC–Al, and CG-HEA-Al composites, respectively. The NC-HEA-Al composite possessed the highest strength due to the best effect of grain refinement, while the SiC–Al composite displayed better ductility attributed to higher work hardening rate after the yield stage than that of the NC-HEA-Al composite. The CG-HEA-Al composites showed the least attractive mechanical properties, related to a poor interface bonding and pre-existing cracks in CG-HEAp. Furthermore, the differences in strengthening mechanisms of the three composites were also discussed. This work provides guidelines for designing metal matrix composites fabricated by powder metallurgy.

Determination of Physicochemical, Cooking and Milling Characteristics of Four Nigerian Rice Varieties

This research work determined the physicochemical, cooking and milling characteristics of four Nigerian rice varieties namely Illa from Southern, Abakaliki South-East, Jemila North and Ofada from West.The physiochemical, milling and cooking properties of rice are solely determining the preference, choice and economy of rice. The four rice varieties grown in different region in Nigeria were investigated for cooking, milling and physical, cooking and chemical characteristics. The result from axial dimension classified all the studied rice varieties as long grains. Illa rice recorded highest value (43.96 g) of 1000 grain weight while lowest value of 20.46 g was observed in Ofada rice. The variation in grain shape were not significant at (P>0.05) and all the tested varieties fall within the slender shapes. All the tested samples displayed good Milling behavior. Ofada rice elongated more than other varieties. The broken percentage was higher and lower in Illa rice (36.72%) and Abakaliki (28.78%) respectively. There were similarities in milling recovering of rice varieties, but Illa had highest expansion (swelling) capacity while Ofada had lowest swelling power. Amylose and gelatinization temperature showed a good relationship, Ofada rice with higher amylose content had lowest gelatinization temperature. The determined cooking time of the rice sample varied from 5.56 to 6.77 mins, Jemila rice will cook faster than other varieties. Illa rice had highest value (353.76%) of water absorption capacity, followed by Abakaliki rice with 185.76% Water Absorption Capacity and Ofada rice which had 158.62% WAC. The lowest value (155.60%) of Water Absorption Capacity was found in Jemila rice variety.

On the synthesis and sintering behavior of a novel Mg-Ca alloy, Part I: Mechanical alloying

A novel Mg-0.7Ca alloy was prepared by the mechanical alloying (MA) process. Different variables were examined in order to obtain the optimum sample with the best milling behavior and potential sinterability. The structural studies were carried out using X-ray Diffractometer (XRD) and scanning electron microscopy (SEM). Crystallite size and lattice strain of the milled samples were examined by Scherrer and Williamson-Hall methods in order to finalize the investigation.
 The optimum milling time was found to be 60 minutes. In addition, a starch-containing sample with a fraction of 2.5 weight percent seemed to have the best microstructural properties, based on SEM observations and crystallite size assessments. Due discussions about the effective phenomena during the mechanical alloying were also included.

Research on Conventional and High-Speed Machining Cutting Force of 7075-T6 Aluminum Alloy Based on Finite Element Modeling and Simulation

In current industrial practice, the finite element modeling of the metal cutting process is essential. In this paper, finite element analysis of conventional and high-speed cutting of 7075-T6 aluminum alloy is carried out. A finite element model of the 7075-T6 aluminum alloy was developed using the Johnson Cook instant on equation to investigate the milling behavior of the alloy under conventional and high-speed conditions. The cutting forces in the X-direction, Y-direction, and Z-direction were predicted analytically for five groups of different Johnson Cook models with different material constants, and the predicted results were compared with the experimentally determined cutting forces to investigate the influence of the Johnson Cook constitutive model parameters on the simulation of the cutting forces of the 7075-T6 aluminum alloy. The results showed that the constitutive model parameters are inconsistent for conventional and higher speed cutting conditions. Under conventional cutting conditions, the JC4 model predicts the material factor cutting forces in good agreement with the experimental results, while under high-speed cutting conditions, the JC5 model predicts the material factor cutting forces in good agreement with the experimental results, but that the finite element model has good applicability in predicting machining performance. Only the experimental data obtained by covering the real strain, strain rate and temperature range to determine the material constant of the Johnson Cook constitutive equation can accurately predict the cutting force in all directions.

Friability of Maize Shoot (Zea mays L.) in Relation to Cell Wall Composition and Physical Properties

Maize (Zea mays L.) is widely cultivated worldwide for food, feed, and fuel uses. Maize forage has become a valuable feed material, and there is much interest in characterizing its friability, as friability may shape feed value through its effect on ingestibility. The objective of this study was to characterize the friability of maize forage based on its milling behavior within a collection of inbred lines of maize. We proposed two friability indexes—Particle Size Reduction (PSR) and Energy Index—and evaluated their ability to discriminate 24 inbred maize lines differing in digestibility. Both the PSR Index and Energy Index effectively highlighted the variability in friability, which could vary by a factor of two regardless of index. These two friability indexes are based on two different milling technologies and therefore on different mechanical stresses inside the mills that could both inform on friability, but on different scales. In order to interpret the observed differences, we characterized the biomass at different scales, from phenotypic observation of the shoot to physical properties of the chopped maize, down to cell wall amount and composition. The friability assessed through these two indexes was mainly inter-correlated: the lower the milling energy, the more friable the fine particles produced. However, we also identified slight differences between the indexes that could be interpreted in relation to structural scale: while the Energy Index primarily informed friability at the cellular scale, the PSR Index also informed friability at the cell wall scale. This study provided key insight into the friability of maize forage and its relation to physical and fiber properties.

Engineering, biochemical, and cooking characteristics of seven eminent cultivars of brown rice: Implication on development of food processing equipment

AbstractThe objective of the present investigation was to substantiate the versatility of brown rice obtained from distinguished Indian varieties with a viable hyphenation with the cultivar influences. Brown rice from seven eminent cultivars, that is, PR‐114, PR‐121, PR‐122, PR‐123, PR‐124, PR‐126, and PR‐127, was in depth characterized by a broad spectrum of properties. Primarily, to comprehend the suggestive milling behavior of paddy and brown rice, their dimensional and physical properties were compared. Secondly, to validate the physicofunctional and cooking prominence of the grain, properties such as amylose and amylopectin content, alkali spreading value (ASV), temperature, and behavior of gelatinization were scrutinized. The assessment of specific nutritional components viz., mineral, vitamins, and fatty acid composition together with textural profile analysis of the cooked grain further validated the primacy of the Indian cultivars. The result presented that the physical and dimensional characteristics of paddy and brown rice varied significantly. In terms of physicochemical and cooking properties, the cultivars PR‐122 and PR‐124 demonstrated considerable pre‐eminence. Furthermore, the ASV, temperature, and gelatinization behavior were principally associated with the starch constituents, that is, amylose and amylopectin. With reference to the mineral, vitamins, and fatty acid composition of the cultivars, PR‐122, PR‐122, and PR‐124 were nutritionally and functionally viable and diverse.Practical applicationsBrown rice is a nutritionally and biofunctionally eminent cereal grain. A viable hyphenation between the anticipated properties demonstrated by these improved and high‐yielding brown rice varieties grown in India would further endorse the cultivation of these cultivars at a larger scale as well as invigorated the farmers to fast‐track their cultivation estate. The physical, physicochemical, gelatinization, cooking, and textural properties of the Indian brown rice cultivars could play a vital role in deciphering and substantiating its processing, nutritional and bio‐viable eminences, which would further confirm their superior demands in the context of regional and national food markets along with food processing industries operating at variable scales.

Understanding Poor Milling Behavior of Voriconazole from Crystal Structure and Intermolecular Interactions

The study investigated the milling behavior of voriconazole (VRZ) subjected to particle size reduction using air jet mill at differential air pressures of 5, 6, 7, and 8 bar for five cycles at each pressure. The crystal structure of VRZ was probed for understanding the fracture behavior from crystal packing and intermolecular interactions using molecular modeling tools of attachment energy (Eatt), density functional theory, and energy framework analysis. Upon milling for different cycles, VRZ showed that size reduction from (D90) 20 to 9 μm and 100% particles could not be milled to sizes below 9 μm, with the increase in either the milling intensity or cycle. The milled samples retained the original crystal lattice as evident from consistent melting endotherm (Tm = 130.75 °C); heat of fusion (ΔHf = 96.52 J/g) values; and the plate-shaped morphology. The powder X-ray diffraction pattern of milled samples consistently showed characteristic peaks of stable form B of VRZ. The crystallographic plane (001) was found to be the most prominent slip and the cleavage plane due to least Eatt and weak noncovalent interactions (6.996 kJ/mol) between 3'H and 4'F functional groups of the neighboring planes. The predicted indentation hardness value of 228.67 MPa further indicated toward the plastic nature of VRZ crystals. Corroborating outcomes from the different molecular modeling tools for VRZ, cleavage along the plane (001) was determined to be energetically favorable, whereas cleavage of isotropic 2D molecular sheets was energetically unfavorable. As milling proceeds and crystal reduces in size, contact surface area and overall interaction energy decrease contributing to plastic behavior of the crystal. It was concluded that crystal plasticity and isotropic 2D molecular sheets along with the orientation of particles to the direction of stress and attrition energy during air jet milling are contributing factors for nonuniform size reduction of VRZ particles.

Influence of End Mill Manufacturing on Cutting Edge Quality and Wear Behavior

One of the decisive factors for the performance of milling tools is the quality of the cutting edge. The latter results from the process control of the individual steps along the tool manufacturing process chain, which generally includes the sintering or pressing of the blanks, grinding, cutting edge preparation, and coating of the tools. However, the targeted and application-specific design of the process steps in terms of high economic efficiency is currently limited by a lack of knowledge regarding the influence of the corresponding process parameters on the resulting cutting edge quality. In addition, there is a lack of suitable parameters that adequately represent the characteristics of the cutting edge microtopography. This publication therefore investigates the influence of manufacturing processes on cutting edge quality and wear behavior of end mills. On this basis, different characterization parameters for the cutting edge quality are derived and evaluated with regard to their ability to predict the wear behavior.

The fluid dynamics of collective vortex structures of plant-animal worms

Abstract