scholarly journals Study on the Formation Mechanism of Surface Adhered Damage in Ball-End Milling Ti6Al4V

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7143
Author(s):  
Anshan Zhang ◽  
Caixu Yue ◽  
Xianli Liu ◽  
Steven Y. Liang
Keyword(s):  
Formation Mechanism ◽  
Complex Geometry ◽  
End Milling ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Milling Process ◽  
Cutting Edge ◽  
Machined Surface ◽  
Surface Machining ◽  
Feed Direction

Ball-end cutters are widely used for machining the parts of Ti-6Al-4V, which have the problem of poor machined surface quality due to the low cutting speed near the tool tip. In this paper, through the experiments of inclined surface machining in different feed directions, it is found that the surface adhered damages will form on the machined surface under certain tool postures. It is determined that the formation of surface adhered damage is related to the material adhesion near the cutting edge and the cutting-into/out position within the tool per-rotation cycle. In order to analyze the cutting-into/out process more clearly under different tool postures, the projection models of the cutting edge and the cutter workpiece engagement on the contact plane are established; thus, the complex geometry problem of space is transformed into that of plane. Combined with the case of cutting-into/out, chip morphology, and surface morphology, the formation mechanism of surface adhered damage is analyzed. The analysis results show that the adhered damage can increase the height parameters Sku, Sz, Sp, and Sv of surface topographies. Sz, Sp, and Sv of the normal machined surface without damage (Sku ≈ 3) are about 4–6, 2–3, and 2–3 μm, while Sz, Sp, and Sv with adhered damage (Sku > 3) can reach about 8–20, 4–14, and 3–6 μm in down-milling and 10–25, 7–18, and 3–7 μm in up-milling. The feed direction should be selected along the upper left (Q2: β∈[0°, 90°]) or lower left (Q3: β∈[90°, 180°]) to avoid surface adhered damage in the down-milling process. For up-milling, the feed direction should be selected along the upper right (Q1: β∈(−90°, 0°]) or upper left (Q2: β∈[0°, 90°)).

scholarly journals Keutuhan Permukaan Bahan Keluli Perkakas Setelah Pengisaran Hujung Menggunakan Perkakas Karbida Bersalut

2012 ◽  
Author(s):  
Che Hassan Che Haron ◽  
Andanastuti Muchtar ◽  
Nik Faizu Nik Kundor
Keyword(s):  
Tool Steel ◽  
Surface Integrity ◽  
End Milling ◽  
Cutting Speed ◽  
Milling Process ◽  
Cutting Condition ◽  
Dry Cutting ◽  
Machined Surface ◽  
Aisi D2 ◽  
Coated Carbide

Projek ini dijalankan bertujuan untuk mengkaji kesan proses pengisaran terhadap keutuhan permukaan keluli perkakas D2. Dalam kajian ini, keluli perkakas kerja sejuk AISI D2 yang telah dikeraskan kepada 62 HRC dimesin menggunakan sisip karbida bersalut CVD boleh indeks yang dipegang oleh perkakas pengisaran hujung berdiameter 20 mm. Siri–siri ujian dijalankan dalam keadaan kering. Penilaian ke atas permukaan yang dimesin melibatkan kekasaran permukaan dan analisis mikrostruktur. Keputusan kajian menunjukkan bahawa tiada hubungan yang jelas di antara variasi kelajuan pemotongan dan suapan terhadap kekasaran permukaan. Umumnya, permukaan yang dihasilkan adalah sangat licin dengan nilai Ra berada dalam julat 0.10 μm – 0.43 μm dan analisis permukaan pada sampel–sampel ujikaji juga mendapati hampir tiada perubahan dapat dikesan pada mikrostruktur bahagian bawah permukaan yang dimesin. Walau bagaimanapun, pada kelajuan pemotongan tertinggi (160 m/min) dan suapan yang tinggi (0.02 mm/sisip), terdapat kesan termampat dan terherot pada mikrostruktur pada kedalaman yang sangat cetek iaitu lebih kurang 2.2 μm dari permukaan termesin. Kata kunci: Keutuhan permukaan, keluli perkakas terkeras, pengisaran hujung, mikrostruktur, perkakas karbida bersalut The effect of milling process on the surface integrity of newly machined surface of D2 tool steel is presented. The hardened AISI D2 (62 HRC) was machined under dry cutting conditions using a 20 mm diameter end–milling tool with indexable CVD coated carbide insert. Analyses revealed that the variation in cutting speeded and feed did not significantly affect the surface roughness of the machined surface. Generally, the surfaces produced are very smooth with Ra values in the range of 0.1 – 0.43 μm, and studies showed almost no microstructure alteration on the machined surfaces. However, at the highest cutting condition, i.e. a cutting speed of 160 m/min, and feed of 0.02 mm/tooth, some compression and distortion effects were detected on the microstructure at the very shallow depth of approximately 2.2 μm from the machined surface. Key words: Surface integrity, hardened tool steel, end-milling, microstructure, coated carbide tool

scholarly journals Study on Cutting Form and Surface Machining Quality of Wheel Tread under Reprofiling

2017 ◽  
Vol 2017 ◽  
pp. 1-12 ◽  
Author(s):  
Jianxi Wang ◽  
Xin Xue ◽  
Yongjie Lu
Keyword(s):  
Residual Stress ◽  
Surface Roughness ◽  
Cutting Speed ◽  
Chip Morphology ◽  
Element Model ◽  
Maintenance Cost ◽  
Serrated Chip ◽  
Machined Surface ◽  
Surface Machining ◽  
Machining Quality

The wheelset maintenance cost is an important part of train maintenance cost. Researchers and railway operators have been closely concerned about the way to minimize residual stress at wheel tread and surface roughness during wheel reprofiling, thereby reducing the wheel damage during operation, extending the wheelset service life, and cutting down wheelset maintenance cost. The present study involves dynamic simulation of tread reprofiling process by building a finite element model of wheel reprofiling, taking the wheel steel as research object. This paper makes a comprehensive analysis of surface roughness and residual stress distribution of wheel tread under different milling parameters. The simulation results indicate that the increase in cutting speed and back cutting depth causes the chip morphology to change while impairing the machined surface quality. Once serrated chip occurs, it means wheel tread machining quality deteriorates remarkably. In this way, the paper associates macroscopic chip morphology with microcosmic surface roughness and internal residual stress to provide theoretical basis for optimization of wheel reprofiling process.

scholarly journals Modeling and optimization of temperature in end milling operations

2019 ◽  
Vol 23 (6 Part A) ◽  
pp. 3651-3660
Author(s):  
Jelena Baralic ◽  
Nedeljko Ducic ◽  
Andjelija Mitrovic ◽  
Pavel Kovac ◽  
Miroslav Lucic
Keyword(s):  
End Milling ◽  
Cutting Speed ◽  
Infrared Camera ◽  
Milling Process ◽  
Optimization Techniques ◽  
Machining Process ◽  
Depth Of Cut ◽  
Machining Processes ◽  
Machined Surface ◽  
Milling Operations

Milling is one of the most important and most complex cutting machining processes. During the milling process, the cross-section of the chip is variable. Also, all milling operations are interrupted processes. The cutting edge of the mill tooth periodically enters and exits from the contact with the workpiece, which leads to periodic heating and cooling during the machining. This periodic change of temperature significantly affects the process of tool wear and therefore the quality of the machined surface. This paper aims at modeling and optimizing the parameters of the machining process to achieve the minimum temperature. In order to perform optimization, it was necessary to perform temperature measurements for the various parameters of the machining process. An infrared camera was used for the temperature measurement. Then, based on the measured values, the mathematical modeling of the temperature was performed depending on the cutting speed, the feed rate and the depth of cut. This model is then optimized using two different optimization techniques.

scholarly journals Velocity Effect Sensitivity Analysis of Ball-end Milling Ti-6Al-4V

2021 ◽  
Author(s):  
Anshan Zhang ◽  
Xianli Liu ◽  
Caixu Yue ◽  
Rongyi Li ◽  
Steven Y. Liang ◽  
...  
Keyword(s):  
Surface Quality ◽  
End Milling ◽  
Cutting Speed ◽  
Surface Damage ◽  
Three Dimensions ◽  
Optimal Range ◽  
Machined Surface ◽  
High Position ◽  
Feed Direction ◽  
Velocity Effect

Abstract Ball-end cutters are widely used in industries of dies, molds, and aerospace, which have the problem of poor machined surface quality due to the low cutting speed near the tool-tip. With the increase in the complexity of parts, it will become more and more difficult to avoid the tool-tip participating in the cutting. In this paper, the velocity effect sensitivity of ball-end cutter is analyzed, and several key positions, including the intersection points of the CWE boundaries, are selected to describe the cutting speed in three dimensions. The relationships between the cutting speed of the critical points and important variables such as: machining inclination angle and the feed direction were investigated. The optimal range of feed direction is obtained when the tool-tip engages in the contact circle. The core aim of the feed direction selection is to make the tool engagement area in a high position by changing the feed direction, to avoid surface damage caused by ploughing and improve the quality of the machined surface. Finally, an experimental study was carried out, and the results corroborate the effectiveness of the selection method. In the experiment, it was also found that cutting-out from the cutter contact position can improve the surface quality in the directions of non-optimal range, and the milling force and chips shape will vary with the change of the feed direction.

scholarly journals SIMULATION OF THE MACHINED SURFACE AFTER END MILLING WITH SELF-OSCILLATIONS

2021 ◽  
pp. 19-27
Author(s):  
Sergei Dyadya ◽  
Yelena Kozlova ◽  
Anton Germashev ◽  
Viktor Logominov
Keyword(s):  
End Milling ◽  
Cutting Speed ◽  
Elastic Equilibrium ◽  
Milling Process ◽  
Aviation Industry ◽  
Machined Surface ◽  
Cutting Surface ◽  
End Mills ◽  
Rough Milling ◽  
The Difference

Thin-walled parts are widely used in the aviation industry. It is mainly carried out with end mills and is accompanied by self-oscillation during rough milling. They negatively affect the quality of the machined surface. Therefore, it is important to model it taking into account the dynamics of the milling process to predict the accuracy. In the early works of the authors, the mechanism of the profile forming of the machined surface was determined. In this case, the identity of the shape of the cutting surface and the oscillogram of part’s oscillations during milling is taken as a basis. The first wave of self-oscillations takes part in the shaping of the machined surface during cut-up milling with self-oscillation, and during cut-down milling - the last wave. The change in the distances of the cut depressions to the position of the elastic equilibrium of the part is periodically repeated from the maximum value to the minimum. Based on this, when modeling the waviness pitch of the machined surface after cut-up milling, it is necessary to know the feed rate and how many cuts were made by the tool from the largest to the smallest depression. When modeling the machined surface after cut-down milling, you need to know the length of the cutting surface. It is calculated based on cutting speed and cutting time. The formula for determining the waviness pitch after cut-down milling is derived taking into account the tool feed. The waviness height of the machined surface after cut-up and cut-down milling is determined as the difference between the largest and smallest depressions. To determine the size of the pitch and the height of the waviness, formulas are derived for converting electrical and time values of oscillograms into linear ones. These formulas also allow you to determine areas of the oscillogram with oscillations of the part during cutting and the resulting surface areas on the profilogram. The methods for modeling machined surfaces were tested after cut-up and cut-down milling with self-oscillation. In this case, the pitch and height of the waviness on the profilograms were compared with those calculated from the results of measurements of the oscillograms. Based on their analysis, refined formulas for calculating the waviness height have been derived. The error between the measurements of the waviness pitch and height and the calculated values is within 6%.

Numerical Simulation of Machined Surface Topography and Roughness in Milling Process

2005 ◽  
Vol 128 (1) ◽  
pp. 96-103 ◽  
Author(s):  
Tong Gao ◽  
Weihong Zhang ◽  
Kepeng Qiu ◽  
Min Wan
Keyword(s):  
Surface Topography ◽  
End Milling ◽  
Equation System ◽  
Milling Process ◽  
Cutting Edge ◽  
Machined Surface ◽  
Ball End Milling ◽  
Starting Point ◽  
Trajectory Equation ◽  
End Milling Process

Machined surface topography is very critical since it directly affects the surface quality, especially the surface roughness. Based on the trajectory equations of the cutting edge relative to the workpiece, a new method is developed for the prediction of machined surface topography. This method has the advantage of simplicity and is a mesh-independent direct computing method over the traditional interpolation scheme. It is unnecessary to discretize the cutting edge or to mesh the workpiece. The topography value of any point on the machined surface can be calculated directly, and the spindle runout can be taken into account. The simulation of machined surface topography is successfully carried out for both end and ball-end milling processes. In the end milling process, a fast convergence of solving the trajectory equation system by the Newton-Raphson method can be ensured for topography simulation at any node on the machined surface thanks to the appropriate choice of the starting point. In the ball-end milling process, this general algorithm is applicable to any machined surface. Finally, the validity of the method is demonstrated by several simulation examples. Simulation results are compared to experimental ones, and a good agreement is obtained.

scholarly journals Fabrication and characterization of resistive double square loop arrays for ultra-wide bandwidth microwave absorption

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Ji-Young Jeong ◽  
Je-Ryung Lee ◽  
Hyeonjin Park ◽  
Joonkyo Jung ◽  
Doo-Sun Choi ◽  
...  
Keyword(s):  
Sheet Resistance ◽  
Manufacturing Process ◽  
End Milling ◽  
Milling Process ◽  
Wide Bandwidth ◽  
Machined Surface ◽  
Array Pattern ◽  
Micro End Milling ◽  
Array Structures ◽  
Printing Processes

AbstractMicrowave absorbers using conductive ink are generally fabricated by printing an array pattern on a substrate to generate electromagnetic fields. However, screen printing processes are difficult to vary the sheet resistance values for different regions of the pattern on the same layer, because the printing process deposits materials at the same height over the entire surface of substrate. In this study, a promising manufacturing process was suggested for engraved resistive double square loop arrays with ultra-wide bandwidth microwave. The developed manufacturing process consists of a micro-end-milling, inking, and planing processes. A 144-number of double square loop array was precisely machined on a polymethyl methacrylate workpiece with the micro-end-milling process. After engraving array structures, the machined surface was completely covered with the developed conductive carbon ink with a sheet resistance of 15 Ω/sq. It was cured at room temperature. Excluding the ink that filled the machined double square loop array, overflowed ink was removed with the planing process to achieve full filled and isolated resistive array patterns. The fabricated microwave absorber showed a small radar cross-section with reflectance less than − 10 dB in the frequency band range of 8.0–14.6 GHz.

scholarly journals Influence of Chatter of VMC Arising During End Milling Operation and Cutting Conditions on Quality of Machined Surface

1970 ◽  
Vol 2 (1) ◽  
Author(s):  
A.K.M.N. Amin, M.A. Rizal, and M. Razman
Keyword(s):  
Surface Roughness ◽  
Metal Cutting ◽  
Metal Removal ◽  
End Milling ◽  
Cutting Speed ◽  
Cutting Conditions ◽  
End Mill ◽  
Machined Surface ◽  
Operating Cycle ◽  
Wide Range

Machine tool chatter is a dynamic instability of the cutting process. Chatter results in poor part surface finish, damaged cutting tool, and an irritating and unacceptable noise. Exten¬sive research has been undertaken to study the mechanisms of chatter formation. Efforts have been also made to prevent the occurrence of chatter vibration. Even though some progress have been made, fundamental studies on the mechanics of metal cutting are necessary to achieve chatter free operation of CNC machine tools to maintain their smooth operating cycle. The same is also true for Vertical Machining Centres (VMC), which operate at high cutting speeds and are capable of offering high metal removal rates. The present work deals with the effect of work materials, cutting conditions and diameter of end mill cutters on the frequency-amplitude characteristics of chatter and on machined surface roughness. Vibration data were recorded using an experimental rig consisting of KISTLER 3-component dynamometer model 9257B, amplifier, scope meters and a PC.  Three different types of vibrations were observed. The first type was a low frequency vibration, associated with the interrupted nature of end mill operation. The second type of vibration was associated with the instability of the chip formation process and the third type was due to chatter. The frequency of the last type remained practically unchanged over a wide range of cutting speed.  It was further observed that chip-tool contact processes had considerable effect on the roughness of the machined surface.Key Words: Chatter, Cutting Conditions, Stable Cutting, Surface Roughness.

Generalized Mechanistic Force System Model of Ball-End Milling for Sculpture Surface Machining

2001 ◽  
Author(s):  
Ismail Lazoglu
Keyword(s):  
End Milling ◽  
Mechanistic Model ◽  
Milling Process ◽  
Force System ◽  
Workpiece Surface ◽  
Surface Machining ◽  
Ball End Milling ◽  
End Milling Process ◽  
Validation Experiments ◽  
Good Agreement

Abstract In this paper, a new mechanistic model is developed for the prediction of cutting force system in ball-end milling process. The key feature of the model includes the ability to calculate the workpiece / cutter intersection domain automatically for a given cutter location (CL) file, cutter and workpiece geometries. Moreover, an analytical approach is used to determine the instantaneous chip load and cutting forces. The model also employs a Boolean approach for given cutter, workpiece geometries, and the CL file in order to determine the surface topography and scallop height variations along the workpiece surface which can be visualized in 3-D. Some of the typical results from the model validation experiments performed on Ti-6A1-4V are also reported in the paper. Comparisons of the predicted and measured forces as well as the surface topographies show good agreement.

A HIGHER FIDELITY MODELING OF THE CUTTING EDGE OF BALL-END MILLING TOOL

2011 ◽  
Vol 10 (01) ◽  
pp. 101-108 ◽  
Author(s):  
XIULIN SUI ◽  
IMRE HORVATH ◽  
JIATAI ZHANG ◽  
PING ZHANG
Keyword(s):  
End Milling ◽  
Milling Process ◽  
Cutting Edge ◽  
Ball End Milling ◽  
Machining Conditions ◽  
Milling Tool ◽  
Efficient Planning ◽  
Pilot Implementation ◽  
Physical Changes ◽  
Milling Forces

Ball-end milling tools have been widely used in machining of complex freeform surfaces. The precision and efficiency of ball-end milling process can be improved by an accurate modeling of the tools, the tools' paths and the machining conditions. However, only rough geometric models have been applied so far, which do not consider the machining conditions and the physical changes. To achieve the best results, an accurate modeling of the cutting edge and the physical behavior of the entire cutter is needed. This paper proposes an articulated model that enumerates both the geometric characteristics and the physical effects acting on the cutting edge-segment of a ball-end milling cutter. The model considers the deformations caused by the milling forces, vibration, spindle eccentricity, together with thermal deformation and wear of the cutter. The mathematical description of the behavior has been transferred into a computational model. The pilot implementation has been tested in a practical application. The first findings show that the proposed theoretical model and implementation provide sufficiently precise information about the behavior of the cutter in virtual simulations; hence it can be the basis of a fully fledged and more efficient planning of milling processes.

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