Milling Tool Research Articles

Optimization of Vortex Tube Design and Performance for Cooling Milling Process

The manufacturing process is required to improve cleanliness and reduce environmental pollution and the exploration of natural resources is limited. One of the manufacturing processes is machining, especially the milling process. The phenomenon during the milling process friction occurs when the workpiece is cut by the milling tool, the effect friction between tool and workpiece occurs temperature rise. To reduce the temperature rise of the milling tool during the workpiece cutting process, an effective and efficient alternative cooling is needed through the use of vortex tubes. The research method was carried out using the Computational Fluid Dynamic (CFD) approach and experiments with the use of inlet pressure = 1-5 Bar, and the parameters of variations in valve shape, number of nozzles, and pipe lengths. The overall results of the CFD and experiment of parameters in inlet pressure on the number of nozzles, valve shapes, and tube lengths, have an impact on the increasing inlet pressure, the higher the thermodynamic characteristics that occur in the vortex tube, but there is a loss of outlet pressure in each parameter. The geometry of the vortex tube selected is the number of nozzles 6, valve fillet shape, and tube length of 50 mm, vortex tube can be used for cooling the milling tool with the addition of a flexible hose at a distance of 5 cm from the tooltip.

Poprawa wydajności narzędzia frezującego poprzez zmniejszenie temperatury w strefie frezowania w zależności od parametrów trybu głównego

Maintenance of equipment and tools used in the overhaul of oil and gas wells depends on the reliability and durability of the tool. The recovery process of damaged wells can be accelerated by choosing the right repair equipment and following the rules and regulations in force. Cutting equipment and tools operating under high pressure and load are deformed, in the cutting zone – dispersion, i.e., a tense situation is created, and as a result of corrosion in the tribonodes, high temperatures, such as 1000–1200°C, are observed. The stress-strain state created in the shear-disintegration zone causes the formation of microcracks in the working zone of the tool, which will grow over a certain period of time. Thus, the cutting elements wear out quickly, in some cases break and quickly fail. In this case, the structural composition of the cutting elements changes, and the structural lattice in metals is destroyed, resulting in riveting. To maintain the equipment and tools used in repairs in working order, one of the important conditions is their special care and adjustment of the mode parameters. This article discusses the increase in the efficiency of the milling tool with the use of cooling agents in the process of milling various metal objects left during accidents in the wellbore. To do this, experimental data were processed, based on regression analysis, mathematical formulas were obtained that describe the temperature process depending on various regime parameters of the grinding process, and their graphical dependences were plotted. A transition from linear regression to non-linear regression has been made. The results obtained make it possible to predict the classification and design schemes of borehole cutters and the choice of composite materials for reinforcing the cutting part.

A Study of Machining Characteristics during Continuous Machining of Circular Pockets Using A6061-T651 High-Speed Steel-Conducting Coated End Mill Tools

A Study of Machining Characteristics during Continuous Machining of Circular Pockets Using A6061-T651 High-Speed Steel-Conducting Coated End Mill Tools

Performance Evaluation of Additively Manufactured and Hybrid Indexable Milling Tools in Machining of AISI4140+QT and Ti-6Al-4V

Abstract Additively manufactured (AM) cutting tools enable new design concepts in tool development concerning lightweight construction, damping behavior, and internal cutting fluid supply. So far, the impact of the layer-by-layer manufacturing technique onto the tool performance during machining of aerospace materials is widely unknown. In this study, the performance characteristics of AM indexable milling tools were investigated and compared to a conventionally manufactured tool of the same geometry. The AM tools were manufactured by laser powder bed fusion (LPBF) from a newly developed bainitic steel alloy. All tools were analyzed with two main focuses. Outside the machine tool, geometrical characteristics and mechanical properties were taken into account. Inside the machine tool, during roughing of AISI4140+QT (42CrMo4+QT) and Ti-6Al-4V (ASTM Ti-Grade 5), tool wear, cutting forces, surface roughness and vibration behavior were evaluated. Three tool concepts were compared, a conventional tool, an AM tool, and a hybrid tool with a conventionally manufactured preform and an AM head. Differences in the performance behavior could be traced back mainly to geometrical inaccuracies caused during postprocessing of the tools. Thus, LPBF-manufactured basic bodies seem to meet the requirements as applications for indexable milling tools. Based on this work, future investigations using AM cutting tools can be carried out assuming a negligible influence of the manufacturing technique onto the tool performance during machining.

Comparative study on cutting performance of different micro-texturing milling tools for preparing the L-PBF-formed TC4 workpieces

Cutting tests were performed on L-PBF-formed TC4 workpieces using different dry-cutting tools and MQL tools. The three aspects of tool wear pattern, cutting force, and surface quality of the workpiece after machining were systematically analyzed and studied for the test results obtained. Changing the micro-texture pattern on the tool effectively reduces the cutting force during milling. With the dry-cutting process, the cutting forces generated by the bionic elliptical micro-texture tool were 44 % lower than those generated by the Original tool. Milling the TC4 surface with the bionic elliptical micro-texture tool under the MQL process produced lower cutting forces of only 8.9 N, 67 % lower than the Original tool. To a certain extent, using bionic elliptical micro-texture tools protects the integrity of the workpiece, and the service life of tool is extended.

Features of processes of high-speed milling with a complex profile tool in the processing of aluminum alloys and composite materials

Complex computational and experimental studies substantiate rational modes of milling of complex contour equiaxed surfaces with high accuracy of shape, dimensions and roughness parameters. Bars made of nanostructured carbide composite (produced by extrusion of WC-Co-Al2O3 bimodal powder mixtures) with increased strength, crack resistance and heat resistance were used as a workpiece material for the manufacture of new original tool designs. The combination of these properties is a necessary prerequisite for the effective operation of the developed designs of multi-blade cutters at high cutting speeds and under conditions of variable cyclic loads. A more complex kinematics of the joint rotational movement of the tool during milling dictates the need for new approaches when assigning rational cutting modes. To obtain reliable calculation formulas, numerical experiments were previously carried out, including simulation of the processing process using the VisualStudio integrated development environment, which supports WindowsForms technology. The ability to display graphical 3D objects was implemented using an additional software product in the form of the Open CASCADE geometric core. Numerical experiments using MathCAD software products and based on the analytical provisions proposed in the work made it possible to evaluate the influence of cutting conditions, geometric parameters of the cutting part of the tool (profile and number of teeth), kinematics of relative movement in the “tool – part” system on the shape of surfaces and contour parameters (roughness obtained during milling. A technique, algorithm and program for the automated calculation of cutting conditions has been developed, which has been verified during full-scale experiments and the manufacture of complex profile parts from aluminum alloys for drives of aerospace products (in the form of a RC profile and parts of a pinion transmission of guidance mechanisms). At the same time, on the basis of a 3D model of products, control programs for CNC machines were created using MasterCAM. The practical significance and technical and economic efficiency of the proposed design and technological solutions is to increase productivity and reduce the complexity of processing (in comparison with the basic options) through the use of new multi-edge carbide tools for high-speed milling (including when processing composite materials).

FUNDAMENTAL ANALYSIS ON THE DYNAMIC BEHAVIOR OF TOOLS WITH STRUCTURED FUNCTIONAL SURFACES IN CUTTING OPERATIONS

The productivity of machining processes is often limited by the occurrence of dynamic effects. The investigated approach intends to counteract tool deflections, and thus to damp and disrupt chatter vibrations by using milling tools with defined functional structures on the flank faces at the frontal cutting edges. For the fundamental investigation of the interactions between structural geometric properties and the tool-workpiece interaction, the engagement situation was geometrically evaluated on a highly abstracted level. Subsequently, hypotheses derived from this were validated experimentally in analogy tests with linear cutting motion. In these cutting experiments, dynamic deflections were induced by an external excitation of the specifically compliant modular tool system. Finally, the technologically most relevant structure variants were applied to milling tools and evaluated with regard to their dynamic behavior. This investigation was preceded by a simulation-based analysis of the material removal on the frontal flank face as a function of the process configuration, which is characterized by multiple intersecting cuts in milling processes. By specifically optimizing and coordinating the structure design and the process configuration, an increase in process stability and thus productivity of at least 100% could be achieved.

On modelling the cutting forces and impact resistance of honed milling tools

In milling operations, cutting tools are subjected to cyclic thermal and mechanical loads due to their intermittent engagement with the workpiece. As a result, they commonly fail due to edge chipping and thermal cracking, among which the former is directly related to the impact at the entry or exit, respectively, in downmilling or upmilling where the chip thickness is maximum. Among the many design factors that affect the impact resistance of milling tools, cutting-edge radius is one of the most important; however, it is often omitted in classic force models. In this paper, a force model that accounts for the edge radius was developed to predict the milling forces. Five sets of milling inserts with custom-made edge radii ranging from 25 to 45 µm were produced and tested. Test results were used to validate the force model and capture the effects of edge radius on the impact resistance of the prepared inserts. Results showed that increasing the edge radius initially improved the impact resistance and increased the tool life. However, increasing the edge radius beyond a certain threshold was proven to be detrimental since it made the tool blunt and drastically increased the cutting forces.

Investigation of machining quality indicators and effect of tool geometry parameters during the machining of difficult-to-machine metal

Producing high-quality surfaces from hard and brittle metals presents a formidable challenge that calls for a meticulous machining strategy and an effective cutting tool. The mechanism of tool failure, chip formation behavior, and micro-morphology of the machined surface are crucial factors in determining a correlation between the used parameters and the machined surface quality. Among the metrics employed to assess the effectiveness of the tool. However, the determination of optimum machining parameters requires the repetition of precise experimental investigations with every change in the cutting conditions. The current research work proposes a set of suggestions for choosing the optimal tool parameters based on the micro-morphological characteristics of the tool and the machining performance indicators. A WC-Co ball end mill tool was used for the machining of an H13 tool steel workpiece to establish the relationship between changes in tool geometrical parameters and the machining performance indicators. Tool geometry with a rake angle of 3°, a clearance angle of 10°, and a helix angle of 32° was found to have the least wear band length at 56 μm. Moreover, the impact of tool geometry on the quality of the surface produced through machining was also investigated.

A generalized closed-form model of cutting energy for arbitrary-helix cylindrical milling tools and its applications

The knowledge of energy consumption of different machine tool production processes leading to products is necessary for energy labeling of machined parts in the increasingly sustainability-aware world thus the need for better machining energy modeling techniques. The milling process dynamics is complicated thus numerical and averaging techniques are hitherto usually applied in the cutting energy modeling thus limiting decision-making. This work proposes a generalized force-based closed-form model for the milling process cutting energy. To the best of the author’s knowledge, the model is the first closed-form cutting energy model for milling which not only applies to the conventional cylindrical milling tools with constant helix angle but also to cylindrical milling tools with any helix angle variation. The demonstrated applications of the proposed model include modeling of milling machine electrical energy consumption, modeling/optimization of milling project energy/efficiency and helix angle optimization for passive reduction of cutting energy. The proposed model is checked with experimentally-verified results in literature. For example, the model agrees with numerically computed cutting energy in literature by absolute error of 0.0320%–0.4025% and modeling of milling machine electrical energy consumption using the proposed model recorded the goodness-of-fit indices of 0.9980 [Formula: see text]-value and −0.1271 mean percentage error compared to a published experimental data. A parametric plot and an optimization based on genetic algorithm showed that increase of helix angle increases cutting energy due to increased influence of edge forces, and the effect is more pronounced at higher helix angles. Various potential applications of the presented model are highlighted in the concluding section.

Image super resolution by double dictionary learning and its application to tool wear monitoring in micro milling

It is an effective means to improve the machining quality of product by monitoring the tool wear conditions in micro milling. However, due to the small size and high speed of the micro milling cutter, it is difficult to capture the clear image of tool wear by CCD camera. Therefore, a double dictionary sparse coding super-resolution (SR) method is proposed to improve the resolution of micro milling tool wear images in this work. Based on the traditional single dictionary, this work proposes the residual dictionary to reconstruct the residual image of the tool, achieving the double dictionary coefficient encoding reconstruction. In order to extract local features of low resolution (LR) tool wear images, the Gobor filter banks are designed, and then the PCA method is used to reduce dimension of extracted features. The dictionary learning based on a single high resolution (HR) image is realized, which reduces the dependence of super-resolution algorithm on large datasets. The effectiveness of Gabor filter and double dictionary for restoration tool wear image details is verified by experiments. Compared with proposed method, traditional interpolation method, sparse coding super resolution model [32] and super resolution convolutional neural network model [26], the PSNR mean value of those methods are 43.62, 42.19, 43.20, 43.21, respectively, which shows that the proposed method has excellent performance in super-resolution reconstruction of micro milling tool images for tool wear monitoring.

A supplementary processing method of residual material in impeller plunge milling

Plunge milling is highly suitable for processing deep groove type parts. In recent years, it has been gradually employed in the machining of integral impeller runners. However, when dealing with impeller runners that exhibit a significant blade twist, there tends to be a considerable amount of residual material left after the plunge milling process. The absence of an accurate computational model to depict these residual materials makes it challenging to plan the subsequent machining path, thereby adversely affecting processing efficiency. To address this issue, a geometric model of the material residual ridge is established. By solving the numerical equation governing the boundary characteristic curve of the residual material, a differential discretization method is employed to discretize the boundary feature curves. These curves are then connected to form a unit straight-line surface, thereby constructing an envelope model of the residual material. In order to carry out the supplementary processing of the residual material, a method is proposed based on the geometric parameters of the material residual envelope model. This method automatically divides the machining area of the residual material and plans plunge milling tool path. Simulation results demonstrate that the established residual material envelope model accurately represents the geometry of the residual material, with a volume error of less than 10 %. The supplementary processing tool path generated using the geometric parameters of the material residual material envelope model removes over 80 % of the material residual material volume. Remarkably, the supplementary processing time accounts for only 10 % of the total time required for the whole runner plunge milling process.

Workpiece temperature investigation in micromilling of titanium alloy

The study of the micromachining process of titanium alloys has intensified due to a greater need to develop micro components for the medical sciences. However, the investigation of the behavior of process variables is still incipient, complex and challenging. Heat and temperature distributions are important aspects for any machining process, so the main objective of this work is to investigate temperature distributions during the micro-milling of the Ti-6Al-4 V alloy combined experimentally with numerical simulations. To carry out the experiments, AlCrN coated carbide end mill tools were used for machining micro slots. During machining, the workpiece temperature is measured using T-type thermocouples welded to the workpiece surface aligned with the tool path. The temperature distribution was also obtained by numerical simulation using the commercial software Third Wave AdvantEdge (version 7.4015). The experimental results showed that the temperature on the surface of the specimen increases from the up-milling side to the down-milling side and that it tends to increase with tool wear. However, the simulated data showed that the temperature is higher in the center of the slot, which is the point with the highest undeformed chip thickness.

On-line milling tool wear monitoring under practical machining conditions

Accurate diagnosis of milling tool wear monitoring during high-speed cutting processes is essential for ensuring machining surface precision, enhancing tool efficiency, and extending the service life of machine tools. However, challenges in data screening during each stage of tool movement and signal migration caused by changes in machining parameters have not been sufficiently addressed. To tackle these issues, this paper presents a novel MB-DAAN model, which considers signals from each stage of tool movement and diagnoses tool wear under dynamic machining parameters. Firstly, the multi-branch classification module is introduced, incorporating two independent classifiers to form a multi-branch classification module. This module adaptively extracts features of tool wear states during the cutting stage. Subsequently, the dynamic adversarial factor adjusts the global and local losses between features, aligning conditional and edge distributions across different machining parameters. The models were evaluated in the milling tool wear data set. MB-DAAN achieving a diagnostic accuracy of 97.3%-a significant improvement compared to CNN, DAN, and DAAN models.

Mathematical Model of Material Removal Rate during Milling of AISI D2 Tool Steel Using Response Surface Methodology

The CNC milling process is one of the most valuable traditional machining processes for machining hardened material by using various coated end mill tools. The attention of the current study has been done on end milling of hardened AISI D2 tool steel which is a commonly used tool steel grade in a press machine. The material removal rate is an essential aspect of improving productivity and reducing lead time and production costs. MRR has been considered as a response in this experimental work. A number of experiments were conducted using the design of the experiment via response surface methodology (RSM). MRR was calculated for each machining performance. A mathematical model of MRR was found using response surface methodology.

Wear behavior of different coated tools in MQL-assisted milling of magnesium-based rare-earth alloys

One of the most important and often employed indicators for describing machinability and machining quality is tool wear. While flank wear is commonly used to gauge the extent of a worn scar, tool wear is characterized more by its shape than its size. To quantify the wear shape, more specific data concerning the wear contour is required. With this aim, the present work addresses the fundamental wear mechanisms and failure modes of several coated tools used in the mechanical milling of rare-earth magnesium (Mg-RE) alloys. Uncoated, edge-strengthened, TiAlN-coated, and diamond-coated tools were tested under dry and minimal quantity lubrication (MQL) conditions. The cutting energy flow and consumption rules governing the tool wear processes were quantified using the exergy analysis theory. The results indicate that the cutting performances of tools and the surface quality are both enhanced by the MQL through reducing adhesion wear. For the unstrengthened tool, a tool wear reduction of 55% is achieved by the MQL. While for the TiAlN-coated tool, the tool wear can be furtherly suppressed by 49%.

Experimental and statistical investigation into surface characteristics in micro milling of bottom pouring/gravity stir cast Al6061 alloy

Micro milling offers the best way to create micro channels; however, the burr formation and surface roughness of the micro channel are difficult to control. Micro channel fabrication and their characterization of stir cast Al6061 are rarely investigated. In the present study, Al6061 alloy was processed by the bottom pouring stir casting method. The micro channels were fabricated on a base and stir cast Al6061 alloys using TiSIN-coated micro end mill tools. The influence of micromachining parameters such as spindle speed, feed rate, and depth of cut on burr formation, cutting force, burr size, and surface roughness was investigated. A comparison was made between the findings obtained from the micro milling of the base and stir cast Al6061 alloys. The surface morphology of fabricated micro channels was analysed and correlated with the roughness profile to understand the channel profile and burr formation. The top burr formation mechanism in stir cast Al6061 alloy was investigated in detail. Low feed rate, low depth of cut, and high spindle speed produced the micro channel with fewer burrs, low surface roughness, and low cutting forces. At the optimum parameter, stir cast Al6061 alloy showed an approximate 420%, 16%, and 300% increase in Fy, Fz, and Ra, respectively, as compared to the base Al6061 alloy. Adhesion wear, built-up edge, and microchipping were found to be the main tool wear mechanisms in micro machining of stir cast alloy. This study directs the choice of cutting parameters for the stir cast micro milling process.

Influence of the process parameters on the grinding result in continuous generating grinding of cutting tools

Continuous generating grinding processes have largely replaced discontinuous profile grinding processes in gear manufacturing due to their higher productivity. On order to transfer the advantage of the productivity benefits of this process to tool grinding, the continuous generating grinding was adapted to the manufacture of cutting tools. However, this novel approach of using continuous generating grinding processes for tool grinding has not been widely investigated. Therefore, the aim of this study is to investigate the influence of cutting speed, feed and radial depth of cut on the process result and thus to generate initial knowledge for the process design. Subsequently, the influence of these parameters on the grinding worm wear as well as on the cutting edge quality and surface properties of the ground milling tools are investigated. The results show that an increase of the radial depth of cut leads to a reduction of the process time by the factor of four without significantly influencing the wear of the grinding worm tooth. Furthermore, an increase of the cutting speed only leads to an increase in the initial wear of the grinding worm after the dressing process. For this reason, the cutting speed offers the potential to further increase the productivity of the process. The microgeometry of the cutting edge of the ground milling tool is mainly affected by the feed and the macro geometry by the feed and radial depth of cut.

Cutting Performance and Wear Behavior of Self‐Developed Silicon Nitride Ceramic End Mills with Optimized Structure for High‐Speed Machining of GH4099

Ceramic tool materials possess a wide range of potential in machining nickel‐based superalloys due to their superior wear resistance, high‐temperature hardness, and strong chemical stability. Herein, a structural optimization scheme of self‐developed silicon nitride ceramic end mill based on stiffness enhancement and performance improvement is proposed, and the key geometric angular parameters scope of the self‐developed ceramic end mills are prioritized via the finite‐element simulation method. Through precision grinding manufacturing and sandblasting pretreatment, the cutting performance and tool wear behavior of three optimized self‐developed silicon nitride ceramic end mills (called S4‐1, S4‐2, S4‐3 respectively) are comprehensively analyzed in comparison, including cutting force, milling temperature, surface quality, and tool life. The results indicate that the cutting force and cutting temperature of all the optimized ceramic end mills are effectively restrained compared with the nonoptimized ceramic tool(S4), and the final workpiece surface roughness is significantly reduced. Further, better surface quality can be obtained by optimized ceramic mills. In terms of tool life, ceramic end mill with optimized construction in best can be increased by up to 1.9 times. The wear mechanism and pattern of the three optimized ceramic milling tools are similar, which is adhesive wear, diffusion wear, and notch wear. Overall, the effectiveness of the optimization scheme for ceramic end mill is successfully verified.

Natural Frequency Analysis on The Base Structure of The CNC Milling Machine Using Simulation and Experimental Methods

The development of national machine tools needs special attention in order to compete with foreign products. Government agency cooperates with industry partners to develop precision CNC milling tools at competitive prices in today's manufacturing industry. One of the problems that often occur in the machine structure is the vibration caused by the resonance between the components that make up the machine, which results in inaccurate machining products. Therefore, it is necessary to do a natural frequency analysis on the milling machine prototype. This research was conducted on the base structure which is the most basic component as a holder for other components. Natural frequency analysis on the base structure uses two methods, namely experimental and numerical simulation using FEA. The results of the two methods are then compared and analyzed for errors that occur. Research parameter so that design does not resonate is that rotational velocity should be 15% above or below the natural frequency. The results show comparison natural frequency error value of numerical simulation method with experimental method and analysis of safety base design against resonance.