Chip Shape Research Articles

Study of electrical pulse heat assisted cutting of titanium alloy TC21 based on the finite element method

Titanium alloys are widely used in various fields because of their high strength, excellent corrosion resistance, and high heat resistance. As a new advanced titanium alloy for aviation, TC21 titanium alloy has high strength and poor machinability. It is of great significance to study the cutting mechanism of this alloy and the methods to improve the machinability of aircraft. In this paper, aiming at the difficult machinability of titanium alloy TC21, EPH online heating assisted cutting method is put forward for the first time. During the cutting experiment, the TC21 alloy sample was heated to a variety of temperatures through the electric pulse thermal heat technique. Chip shape and cutting force under different heating temperatures were obtained by cutting experiments. In order to study the influence of the heat-assisted cutting process on the machining of TC21 alloy, the orthogonal finite element model was proposed to simulate the heat-assisted cutting process of TC21 alloy. Through this simulation, chip formation, cutting force, and cutting temperature variation were all obtained. The chip formed by the simulation was in accordance with the actual chip. The results demonstrate that the influence of heat-assisted machining on chip morphology of titanium alloy is relatively small, but it has a significant influence on cutting force and surface roughness. The results show that when the sample is heated to 600°C, the surface quality is the best and cutting force can be reduced by more than 40%.

Effect of high-speed steel screw drill geometry on cutting performance when machining austenitic stainless steel

Drilling into the solid material is one of the basic technological operations, which creates a cylindrical hole in an appropriate time with required quality. Drilling operation demands a favourable removal of chips from the cutting area because a creation of an undesirable shape of chips can impart a lower quality of the drilled hole corresponding with the generation of excess heat due to the intense contact of the chip with drill. The solution for a proper machining is a suitable modification of the drill geometry i.e., point and clearance angles as presented in current study. The tested drills are made of M35 high-speed steel characterized by a very thin core at the point of the drill. An interesting feature of the drills is the use of cutting speed higher than 30 m min−1, with the feed of 0.2 mm per revolution. The surface roughness (Ra and Rz lower than 1 µm and 6 µm respectively), cylindricity (0.045 mm), roundness (0.025 mm), perpendicularity of the hole axis (0.025 mm), diameters and position of the individual holes were achieved for a drill with point angle 138.32°and clearance angle 6.92 respectively. The increase of the drill point angle by 6° resulted in the decrease in the feed force of more than 150 N. In addition, an increase of the clearance angle by 1° resulted with a decrease in the feed force of 70 N. The results of the experiment showed that with the correct geometry of the tool the effective machining without using internal cooling can be realised.

Preparation and properties of the biogas decarbonization byproduct of nano-CaCO3 in a microfluidic device and computational fluid dynamics simulation

Biogas decarbonization is a key step in increasing the calorific value of biogas to meet demand. However, the release of CO2 into the atmosphere from the biogas decarbonization process increases carbon emissions. The use of Ca(OH)2 slurry to absorb and remove CO2 can achieve a carbon-free biogas purification process, and it is also an effective method for preparing CaCO3. This study prepared biogenic nano-CaCO3 using CO2 from biogas decarbonization with a newly fabricated microfluidic device and novel microfluidic chips were also made. The reaction pH, microfluidic chips, and total flow rate were parameters varied and studied for optimization. In addition, computational fluid dynamics (CFD) simulated the flow mixing and mass transfer of Ca(OH)2 solution and CO2-rich water in the microfluidic chips. Results showed the weakly alkaline condition (pH = 7.5), microfluidic chips with < 10 μm gaps, and > 100 mL/min total flow rate enhance CO2 absorption. At those conditions, the microfluidic device prepared 30 nm-sized nano-CaCO3 abundantly. Further, the CFD simulation proved the necessity to select the appropriate ratio of Ca(OH)2 solution and CO2-rich water to obtain nano-CaCO3 with stable particle size. CFD also informed that increasing the length of the inlet and outlet of the reaction chamber and changing the chip shape can effectively improve CaCO3 production.

Study of the finish turning process based on the Parameter Space Investigation method

This paper describes a future-proof Design of Experiment (DoE) method, namely the Parameter Space Investigation (PSI) method. This method reduces the number of test points compared to other DoE approaches, such as single factor design, full factorial design, fractional factorial design, and central composite design, and the number of test points is sufficient for statistical analysis. It allows an efficient analysis of process phenomena, among others, some cutting effects and surface texture forming. It has been shown that in the space of cutting parameters studied, changes in the chip thickness ratio Kh have extreme points, which can be caused by vibration or the build-up-edge formation, and different types of chip shapes are observed. Changes in Kh correlate with chip shapes. In the ranges of depth of cut ap = 0.2 − 1.2 mm and feeds f = 0.05 − 0.4 mm/rev, depending on cooling conditions, the changes in cutting force reach up to 80%. For cutting speeds vc = 50 − 200 m/min and feed rates f = 0.03 − 0.17 mm/rev, the relationships Ra = f(vc,f) are complicated, and the PSI method ensures finding minimum Ra values and areas of physicochemical phenomena. Optimizing the turning conditions over a wide range, at the first stage, the minimum Sa values were obtained in the area of vc = 150 − 300 m/min and f = 0.05 − 0.22 mm/rev, and at the second stage in the areas of vc > 240 m/min and f = 0.03 − 0.07 mm/rev and vc = 100 − 120 m/min and f = 0.01 − 0.13 mm/rev. In addition, the shaping of the machined surface was affected by vc, f, and their interaction. Compared to the first optimization stage, the second stage provided Sa values almost 2 times smaller. It has been proven that the PSI method is effective and can be widely used in various areas of multivariate experimental research and optimization of cutting processes.

Determinants of Consumer Demand and Preference on Banana Chips in Central Aceh District

Chips agroindustry is one of the potential businesses to be developed in Central Aceh Regency, but its development efforts are still faced with various obstacles, including; policy development has notbeen carried out in an integrated and focused manner. The demand for banana chips in Pegasing District is influenced by four factors, namely the price of banana chips, the price of cassava chips, income, and the number of dependents. Based on the results of the regression analysis, the value of sig F is smaller than alpha (0.000 < 0.05), which means that simultaneously these factors have a significant effect on the demand for banana chips in Pegasing District. The results of the partial analysis are only income variables, number of dependents and tastes that have a significant or significant effect on the demand for banana chips in Pegasing District because the sig t value of the three variables is smaller than the alpha value (0.000 < 0.05). Based on qualitative descriptive analysis through consumer responses to the attributes of banana chips, it is known that the attributes of banana chips that become consumer preferences are banana chips with a savory banana chips taste, the shape of banana chips that are wholeround and also those that have a dry texture, not rancid and the level of crispness of the chips. tall banana. The consumer’s attitude towards the attribute of banana chips that is most considered in purchasing decisions of banana chips in Pegsing Regency is taste. The index of consumer attitudes towards the attributes considered in the decision to purchase banana chips in Pegasing District, from the highest to the lowest, are taste (I), texture (II), and shape (III).

Effect of Wear on Vibration Amplitude and Chip Shape Characteristics during Machining of Eco-Friendly and Leaded Brass Alloys

The dynamic stability of the machining set and the entire cutting process, together with the appropriate form of chips generated during machining under the given conditions, are the basic prerequisites for autonomous machining in accordance with the Industry 4.0 trend. The research, based on a newly designed method, aims to study the frequency response of the machining system to different values of tool wear and cutting speed, which cause the worsening of the machined parts’ quality and the instability of the whole cutting process. The new idea is based on the inverse principle, in which the wear with various values of VB was artificially prepared in advance before machining. Consequently, the effect of artificial wear and cutting speed on vibration and chip shape characteristics were studied. Three types of brass alloys were used within the experiments as the machined materials. Measured data were statistically processed and the desired dependencies were plotted. Chips were collected for each combination of machining conditions, while the article presents a database of the obtained chip shapes at individual cutting speeds so that they can be compared and classified. The results showed that brass alloys CW510L and CW614N exhibit an average of three times lower vibration damping compared to the CW724R alloy, while relatively good chip formation was noted in the evaluated machining conditions even without the use of a chip breaker. The problematic chip shape occurred only in some cases at the machining of CW510L and CW724R, which cannot be generalized.

Effect of Coated Composite Micro–Texture Tool on Cutting Shape and Cutting Force during Aluminum Alloy Cutting

Aluminum alloy materials are very difficult to break in the processing process; chip accumulation leads to poor processing stability. In this paper, a coated composite micro–textured tool is presented. The influence of coated composite micro–textured tool on chip shape and cutting force under the same cutting parameters is studied. Firstly, the combination of cutting force and cutting temperature is optimized based on cutting test. Secondly, combined with the finite element simulation technology, three kinds of composite micro–texture tools are tested to determine the same cutting parameters, tools and workpiece materials, and optimize the composite micro–texture combination from the angle of chip shape, cutting temperature and cutting force. Finally, on the basis of optimizing the microstructure combination, the optimization of the cutting performance of aluminum alloy by coating material is studied. It was found that the chip was more easily broken in the composite microstructure when two tools were used. The cutting force decreased by 25% and the cutting temperature decreased by 9.09% compared with the non–micro–texture tools. The cutting temperature and cutting force decreased by 3% and 4.99% compared with those of uncoated composite microstructure.

Comparative study on MQL milling and hole making processes for laser beam powder bed fusion (L-PBF) of Ti-6Al-4V titanium alloy

In this experiment, the laser powder bed fusion (L-PBF) formed prefabricated hole specimens were machined at a certain cutting speed by changing the feed rate and using the dry cutting and micro lubrication (MQL) assisted cutting process with the aim of improving the surface accuracy and quality of additively manufactured titanium alloy holes. The machining method of milling was used to compare and analyze the surface quality, cutting force, tool wear, and chip shape of the specimens under different machining processes. The results have shown that the actual dimensions of the original holes formed by L-PBF are generally smaller than the theoretical ones, mainly due to the collapsed areas and powder adhesion zones. The best machining quality of the hole structure was obtained with the feed rate of 20 mm/min and the MQL-assisted process. The burr was relatively minimal, with an average dimensional error of only 77 μm. The overall cutting forces are high and fluctuate during dry cutting. The MQL-assisted cutting process can significantly reduce the cutting forces compared with the dry cutting conditions, especially the radial cutting forces, during machining. At a feed rate of 10 mm/min, the overall maximum radial cutting force is reduced by 72 %, and the overall average axial cutting force is reduced by 35 %. At a feed rate of 30 mm/min, the overall maximum axial cutting force is reduced by 37 %. The tool wear was severe, and many chips adhered to the tool under dry-cutting conditions. The tool wear was significantly reduced under the MQL process, presumably because the atomized lubricant formed an oil film on the tool, powder, and substrate, significantly reducing friction and chip adhesion. In addition, under the oil film, the residual metal powder is like the ball in a ball bearing, significantly reducing the friction between the tool and the substrate.

Development of an epoxy-based millimeter absorber with expanded polystyrenes and carbon black for an astronomical telescope.

We recently developed and characterized an absorber for millimeter wavelengths. To absorb a millimeter wave efficiently, we had to develop a low reflection and high absorption material. To meet these requirements, we added polystyrene beads in the epoxy for multiscattering in the absorber. The typical diameter of polystyrene beads corresponded to the scale of Mie scattering for photon multiscattering in the absorber. The absorber consists of epoxy, carbon black, and expanded polystyrene beads. The typical size of the expanded polystyrene beads is consistent with the peak of a cross-section of Mie scattering to increase the mean free path in the absorber. By applying this effect, we successfully improved the absorber's performance. In this paper, we measured the optical property of epoxy to calculate the Mie scattering effect. Based on the calculation results, we developed eight types of samples by changing the ratio in the absorber material. To compare the eight samples, we characterized the reflectance and transmittance of the absorber in a millimeter wavelength. The measured reflectance and transmittance of a 2mm thick sample with optimized parameters are, respectively, less than 20% and 10%. We also measured the transmittance in a submillimeter wavelength. The measured transmittance is less than 1%. The shape of absorber can be modified for any shape, such as chip and pyramidal shapes. This absorber can be used to mitigate the stray light of a millimeter wave telescope with any shapes.

Particle tracking velocimetry as a method for chip ejection studies during groove milling of particleboard

Studies on chip ejection from tools provide important information for the design of tools and effective chip collection elements used in woodworking machines. Among the chip properties, chip motion and its distribution are of particular interest for the design process. Until now, chip velocities have only been measured by manual tracking over a high-speed image sequence, which allows only a small scope of inspection. Here, we present the use of high-speed imaging in combination with particle tracking velocimetry as a new method for the semi-automatic evaluation of the magnitudes and directions of chip velocities. The methodology was tested in groove milling of particleboard. It was found that state-of-the-art particle tracking algorithms are suitable for quantitative analysis of chip motion in high-speed images. Therefore, spatial and temporal analysis of the chip velocity along the tool circumference are feasible and are presented here. In addition to chip velocity, chip collisions with the tool or other chips can be observed. This research also shows that image evaluation of chip sizes and shapes is potentially possible. In summary, the presented work provides methods that can quantitatively describe chip motion after chip formation. The experiments indicate that with each tooth engagement, new chips are formed, which initially move into the chip space at a median velocity higher than the cutting speed. After collisions with the tool and interparticle collisions, the particles leave the chip space of the tool at lower speeds. The machining tests performed with different process settings showed differences in the analysis results of chip movement. In the future, the presented methodology offers the possibility of investigating the relationships between tooth and chip space geometries, as well as different materials and the chip ejection of tools. Thus, the presented methodology provides a basis for creating a more general understanding of chip motion from machining operations, which can lead to innovations and improvements in chip collection.

Hard Turning Performance Investigation of AISI D2 Steel under a Dual Nozzle MQL Environment

In recent years, hard turning has emerged as a burgeoning cutting technology for producing high-quality finishing of cylindrical-shaped hardened steel for a variety of industrial applications. Hard turning under dry cutting was not accepted because of the generation of higher cutting temperatures which accelerated tool wear and produced an inferior surface finish. Nowadays, minimum quantity lubrication (MQL) is widely accepted in hard turning to reduce the problems encountered in dry cutting. This research aimed to augment the MQL performance in the hard turning process of AISI D2 steel by applying a novel concept, namely, a dual jet nozzle MQL system that supplies the cutting fluid into the cutting zone from two different directions. The performances of hard turning are discussed using machinability indicator parameters, such as surface roughness, tool wear, cutting temperature, power consumption, noise emission, and chip morphology. The dual nozzle MQL greatly reduced the friction between contact surfaces in the cutting zone and provided improved surface quality (Ra = 0.448 to 1.265 µm). Furthermore, tool flank wear was found to be lower, in the range of 0.041 to 0.112 mm, with abrasion and adhesion being observed to be the main mode of wear mechanisms. The power consumption was greatly influenced by the depth of cut (46.69%), followed by cutting speed (40.76%) and feed (9.70%). The chip shapes were found to be helical, ribbon, and spiral c type, while the colors were a metallic, light blue, deep blue, and light golden.

A Deep-Hole Microdrilling Study of Pure Magnesium for Biomedical Applications.

The mechanisms of deep-hole microdrilling of pure Mg material were experimentally studied in order to find a suitable setup for a novel intraocular drug delivery device prototyping. Microdrilling tests were performed with 0.20 mm and 0.35 mm microdrills, using a full factorial design in which cutting speed vc and feed fz were varied over two levels. In a preliminary phase, the chip shape was evaluated for low feeds per tooth down to 1 μm, to verify that the chosen parameters were appropriate for machining. Subsequently, microdrilling experiments were carried out, in which diameter, burr height and surface roughness of the drilled holes were examined. The results showed that the burr height is not uniform along the circumference of the holes. In particular, the maximum burr height increases with higher cutting speed, due to the thermal effect that plasticizes Mg. Hole entrance diameters are larger than the nominal tool diameters due to tool runout, and their values are higher for high vc and fz. In addition, the roughness of the inner surface of the holes increases as fz increases.

СИМУЛЯЦІЯ ПРОЦЕСУ POWER SKIVING ДЛЯ НАРІЗАННЯ ВНУТРІШНЬОГО ЗУБЧАСТОГО КОЛЕСА З МОДЕЛЮВАННЯМ НЕДЕФОРМОВАНОЇ СТРУЖКИ

Aim. The aim of this paper is to create a 3D model of the undeformed chips produced during the cutting of an internal gear ring. By modelling the power skiving process, it is necessary to investigate the influence of various geometric and technological parameters on the thickness and cut area of the chips produced. Method. By simulating the gear turning process, it is possible to reproduce the cutting of the gear teeth and accurately determine the geometric parameters and the shape of the undeformed chip at each moment. A model of the workpiece and cutting tool was created in the CAD system environment and the position of the bodies relative to each other was determined with the highest possible accuracy. Results. Following the simulations, graphical dependencies of the change in thickness and area of the undeformed chip cross-sections on module, feed, tool position and tilt were produced. The nature of the influence of these parameters on the cup cutter blades was also determined. The scientific novelty and practical significance. The study makes it possible to analyse the dynamics of changes in the geometric dimensions of undeformed chips produced by each cutter blade and to identify the most stressed zones. Furthermore, knowing the complete chip information, it is possible to study the force characteristics of the cutting process on the blades, heat flows, calculate machining errors and predict tool wear. After a complete analysis of all the results of the Power Skiving process study, it is possible to recommend the optimum operating modes of the available equipment for a given gear, taking into account the number of teeth, their module and the workpiece material.

Linear woodcutting of European beech: experiments and computations

Hardwood species are becoming increasingly important with the growing need for a diversity of forests that have recently been facing global temperature changes or conifer pests. This further leads to the growth of its potential as a building material that may originate from sustainable production. As hardwoods need to be properly processed, the article deals with the disintegration of European beech. The influence of wood grain direction, uncut chip thickness and cutting speed on the cutting force magnitudes was experimentally investigated using the device with a rotating arm of approximately 4 m in diameter. Then, the disintegration process was modelled using the finite element method in Abaqus/Explicit. The developed material model consisting of orthotropic elasticity and plasticity with rate-independent and rate-dependent tensile–compressive failure asymmetry was implemented through the user subroutine, while the crack initiation and propagation were realized using the element deletion technique. The computationally predicted average values of cutting forces and chip shapes were, except for a few tests, in good agreement with the experiments. It means that the model may be used for further investigation, such as the influence of tool wear.

절삭 시뮬레이션에 사용되는 구성방정식 종류별 절삭력 예측

The constitutive equation shows the difference in the predicted result value related to cutting according to the coefficient value and type. Therefore, in this study, the cutting force and chip shape obtained from the cutting test for each cutting condition were applied as standards. And the simulation results applying the constitutive equation were compared. The constitutive equations used in this study are the Power-Law, Johnson-Cook, and S-K constitutive equations. Since the Power-Law constitutive equation is basically applied to the cutting simulation, it was used as the internal material property, and the Johnson-Cook constitutive equation and the S-K constitutive equation determined the coefficient value and performed simulation as a user property. As a result, it was confirmed that the tangential force and chip shape prediction in the cutting force and chip shape prediction of AAl7075 material were valid through simulation using the S-K constitutive equation.

CAD modelling of the chip shape in case of ball-end milling

The manufacturing of free form surfaces is a common task in the field of mould and die manufacturing. The changing circumstances of the finishing milling with ball-end milling cutter has effect on the shape and the volume of the chip, the load of the cutting tool and the generated surface roughness. The aim of the article is to investigate the changing of the chip thickness and volume in case of ball-end milling by 3D CAD modelling, and to analyse the changing of the circumstances in case of milling of a convex and a concave surfaces.

Machinability Studies on Commercially Pure Titanium (Grade-2) Under Cryogenic Condition

ABSTRACT In this investigation, commercially pure titanium (grade2) was machined under cryogenic conditions at high cutting speeds with varying feed rates and depths of cuts. A Taguchi orthogonal array is used to choose the cutting parameters. The output responses include experimentally confirmed cutting forces (Vc), surface roughness (Ra), tool wears, chip production, and chip shape. In order to obtain the final significant machinability, an excellent parametric combination for the work section was obtained by GRA. ANOVA was used to estimate the percentage contributions of the control components. Finally, the cryogenic liquid significantly lowers the cutting temperatures even at high cutting speeds, producing chips with favorable serrations.

Influence of cutting parameters and modes on coal fracture efficiency

The efficiency of the process of coal cutting by coal cutting machines depends, all other things being equal, on the method of coal fracture, characterized by the number and relative location of the exposed planes, as well as by the orientation of the main plane of the cutting tool relative to the fracture surface. With greater degree of exposure of the face surface, coal fracture is easier. In this regard, the article considers various types of cutting with characteristic cross-section shapes of chips, and assesses them from the point of view of the energy intensity of the process. The main operating parameters that determine efficiency of the coal cutting process are the thickness, width and cross-section of chips, the ratio of which governs the cutting energy intensity and productivity. The patterns of the influence of operating parameters on the force and energy parameters of the cutting process are considered. It is found that for almost all types of cutting, with increasing chip thickness, the energy intensity of cutting and the degree of coal fragmentation reduce along a hyperbola and stabilize at the chip thickness exceeding 3&ndash;5 cm. The theoretical chip width conditioned by the distance between the side faces of the cutter at the height of their contact with rock mass depends on the brittleness of coal, chip thickness, type of cutting, shape of the cutting edges and surfaces of the cutting part, cutting angles, as well as on the sharpening and setting of the cutter. The formulas for determining the theoretical values of the chip width for various designs of the cutting part of the cutters are given. The joint effect of the chip thickness and width on the specific energy consumption during cutting is estimated. To analyze and quantify the effect of operating parameters on energy consumption during cutting, the face exposure coefficient is proposed, which is the ratio of the specific energy consumption at the studied values of the chip thickness and width to the energy consumption in the reference cutting mode with the same chip thickness. The theoretical dependences are obtained for determining the optimal values of the face exposure coefficient and chip width during operation of shearers and ploughs. It is found that the feed rate and cutting speeds, as well as their ratio, practically have no influence on the loads on the cutters and, therefore, can be ignored in the calculations for choosing parameters of excavating machines.

Oscillations of Cutting Tool as a Useful Effect in Turning and Drillingm

The paper presents the fixtures with movably mounted turning and drilling cutting tools. The fixtures were developed on the principle of oscillating tooltip similar to the principle of the ultrasonic vibration-assisted machining process. However, presented fixtures do not need an electricity source and utilize mainly forced and self-excited oscillations. In general, the tool vibrations during the cutting process are recognized as a negative phenomenon as it causes a shortening of the tool life and worsens the roughness of the machined surfaces. However, a deeper understanding of the cutting process proposes possible positive effects of tool vibration in terms of chip shapes, flank wear, chip volume coefficient, and quality of the machined surface. Experimentally obtained dependence of mentioned quantities is provided in the paper.

Improved chip control on PCD tools by positioning of brazed chip breakers

A brazed chip breaker capable of controlling the chip curling and flow is proposed on the rake face of a polycrystalline diamond (PCD) tool to obtain ideal chip shape of aluminum alloy materials. Two new position parameters, the breaker-point distance and the rotation angle of chip breaker, are proposed for positioning the chip breaker on the rake face of PCD turning tool. Influences of two position parameters of the chip breaker on the chip curling and chip flow direction are studied through finite element simulations and cutting experiments. The appropriate breaker-point distance can improve the up-curling and back-flow of the chip, and control the chips flow to the tool flank face to form a C-shaped chip. After setting the appropriate breaker-point distance, increasing the rotation angle of chip breaker can promote the trend of side-curling and side-flow of the chip, which is beneficial to the formation of short helical chip. Based on the chip-breaking criterion and the geometric relationship between the chip breaker and tool rake face, the equations of two position parameters of chip breaker are established, and effective chip breaking can be achieved within the reasonable range of chip breaker position parameters calculated by the established equations. The proposed chip breaker which position parameters are convenient to measure and install can be brazed on turning and drilling tools to obtain needed chip shape of aluminum alloy materials. • Proposed two position parameters of chip breaker for PCD turning tools. • Derived a set of equations to determine the effective range of the two position parameters. • Analyzed the influence of the position parameters on the chip curl, chip flow direction and chip shape.