scholarly journals Surface Integrity Investigation to Determine Rough Milling Effects for Assessment of Machining Allowance for Subsequent Finish Milling of Alloy 718

2021 ◽  
Vol 5 (2) ◽  
pp. 48
Author(s):  
Jonas Holmberg ◽  
Anders Wretland ◽  
Johan Berglund ◽  
Tomas Beno ◽  
Anton Milesic Karlsson
Keyword(s):  
Surface Integrity ◽  
Milling Process ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Milling Operations ◽  
Milling Operation ◽  
Machining Allowance ◽  
Rough Milling

The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work is to use a case study to investigate how a prior rough milling operation affects the finish machined surface and, after that, to use this knowledge to design a methodology for how to assess the machining allowance for subsequent milling operations based on residual stresses. Subsequent milling operations were performed to study the final surface integrity across a milled slot. This was done by rough ceramic milling followed by finish milling in seven subsequent steps. The results show that the up-, centre and down-milling induce different stresses and impact depths. Employing the developed methodology, the depth where the directional influence of the milling process diminishes has been shown to be a suitable minimum limit for the allowance. At this depth, the plastic flow causing severe deformation is not present anymore. It was shown that the centre of the milled slot has the deepest impact depth of 500 µm, up-milling caused an intermediate impact depth of 400 µm followed by down milling with an impact depth of 300 µm. With merged envelope profiles, it was shown that the effects from rough ceramic milling are gone after 3 finish milling passes, with a total depth of cut of 150 µm.

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.

Stability Analysis of a Variable Spindle Speed Milling Process

2005 ◽  
Author(s):  
X.-H. Long ◽  
B. Balachandran
Keyword(s):  
Milling Process ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Infinite Dimensional ◽  
Dimensional Matrix ◽  
Finite Dimensional ◽  
Milling Operations ◽  
Milling Operation ◽  
The Stability ◽  
Delay Differential

In this effort, a stability treatment is presented for a milling process with a variable spindle speed (VSS). This variation is caused by superimposing a sinusoidal modulation on a nominal spindle speed. The dynamics of the VSS milling process is described by a set of delay differential equations (DDEs) with time varying periodic coefficients and a time delay. A semi-discretization scheme is used to discretize the system over one period, and the infinite dimensional transition matrix is converted to a finite dimensional matrix over this period. The eigenvalues of this finite dimensional matrix are used to determine the stability of the VSS milling operation with respect to selected control parameters, such as the axis depth of cut and the nominal spindle speed. The benefits of VSS milling operations are discussed by comparing the stability charts obtained for VSS milling operations with those obtained for constant spindle speed (CSS) milling operations.

Machining Evaluation of High-Speed Milling for Thin-Wall Machining of Al7075-T651

2014 ◽  
Vol 541-542 ◽  
pp. 785-791 ◽  
Author(s):  
Joon Young Koo ◽  
Pyeong Ho Kim ◽  
Moon Ho Cho ◽  
Hyuk Kim ◽  
Jeong Kyu Oh ◽  
...  
Keyword(s):  
Surface Roughness ◽  
Surface Integrity ◽  
Cutting Forces ◽  
High Speed ◽  
Surface Condition ◽  
Cutting Conditions ◽  
Depth Of Cut ◽  
Thin Wall ◽  
Machined Surface ◽  
High Speed Milling

This paper presents finite element method (FEM) and experimental analysis on high-speed milling for thin-wall machining of Al7075-T651. Changes in cutting forces, temperature, and chip morphology according to cutting conditions are analyzed using FEM. Results of machining experiments are analyzed in terms of cutting forces and surface integrity such as surface roughness and surface condition. Variables of cutting conditions are feed per tooth, spindle speed, and axial depth of cut. Cutting conditions to improve surface integrity were investigated by analysis on cutting forces and surface roughness, and machined surface condition.

Fractal-Based Analysis of the Relation Between Surface Finish and Machine Vibration in Milling Operation

2019 ◽  
Vol 19 (01) ◽  
pp. 2050006 ◽  
Author(s):  
Muhammad Owais Qadri ◽  
Hamidreza Namazi
Keyword(s):  
Surface Quality ◽  
Complex Structure ◽  
Vibration Signal ◽  
Depth Of Cut ◽  
Machining Parameters ◽  
Machined Surface ◽  
Machine Vibration ◽  
Milling Operation ◽  
Surface Changes

Analysis of surface quality of machined workpiece is an important issue in machining of materials. For this purpose, scientists analyze how the texture of machined surface changes due to different conditions. Machine vibration is one of the factors that highly affects the surface quality of machined surface. In this research, we analyze the relation between machine vibration and surface quality of machined workpiece. For this purpose, we employ fractal theory and analyze how the complex structure of machined surface changes with the complex structure of machine vibration signal in case of variations of machining parameters, namely, depth of cut, feed rate and spindle speed, in milling operation. Based on the results, variations of surface quality of machined workpiece are related with the variations of complexity of machine vibration signal. The method of analysis employed in this research can be applied to other machining operations in order to find the relation between machine vibration and surface quality of machined workpiece.

Технологическое обеспечение качества поверхностного слоя стекловолоконных композитов при концевом фрезеровании

2020 ◽  
Vol 22 (4) ◽  
pp. 31-40
Author(s):  
Andrei Markov ◽  
◽  
Vyacheslav Nekrasov ◽  
Jian Su ◽  
Azhar Salman ◽  
...  
Keyword(s):  
Composite Materials ◽  
End Milling ◽  
Experimental Studies ◽  
Milling Process ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Scientific Publications ◽  
Experimental Assembly ◽  
Operation Results

Introduction. Today fiberglass is one of the most common composite materials. Therefore, its mechanical processing continues to be the subject of many studies. In many scientific publications, the influence of cutting modes and structural and geometric parameters of the tool on the roughness of the machined surface, cutting forces and wear of the cutting tool has been established. The purpose of this work is to study the effect of machining modes on delamination and roughness of fiberglass composites during end milling, as well as testing the hypothesis about the effect of torque on the delamination. The relevance of the study is due to the fact that delamination, along with roughness, has a significant impact on the quality of processing and subsequent assembly of the finished product. A criterion is proposed for assessing the magnitude of the delamination of composite materials during its machining. The results of experimental studies of the torque on the cutter, the relative coefficient of delamination and surface roughness from cutting conditions are presented. Methods: factorial experiment using an experimental assembly developed by the authors based on a piezoelectric torque sensor. The installation allows real-time recording of the change in torque during the milling process, depending on the modes of operation. Results and Discussion. A comparative analysis of the obtained dependences showed that the torque is directly related to delamination. To reduce the delamination, the depth of cut should be decreased, and in order to ensure the specified productivity, the feed and the rotational speed of the cutter should be increased. The presented results confirm the prospects of the developed approach aimed at machining new classes of composite materials.

RSM Based Investigations on the Effects of Cutting Parameters on Surface Integrity during Cryogenic Hard Turning of AISI 52100

2015 ◽  
Vol 15 (3) ◽  
pp. 309-318 ◽  
Author(s):  
Suha K. Shihab ◽  
Zahid A. Khan ◽  
Arshad Noor Siddiquee
Keyword(s):  
Surface Integrity ◽  
Feed Rate ◽  
Hard Turning ◽  
Desirability Function ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Depth Of Cut ◽  
Machined Surface ◽  
Aisi 52100 ◽  
Model Equations

AbstractEffect of cryogenic hard turning parameters (cutting speed, feed rate, and depth of cut) on surface roughness (Ra) and micro-hardness (µH) that constitute surface integrity (SI) of the machined surface of alloy steel AISI 52100 is investigated. Multilayer hard surface coated (TiN/TiCN/Al2O3/TiN) insert on CNC lathe is used for turning under different cutting parameters settings. RSM based Central composite design (CCD) of experiment is used to collect data for Ra and µH. Validity of assumptions related to the collected data is checked through several diagnostic tests. The analysis of variance (ANOVA) is used to determine main and interaction effects. Relationship between the variables is established using quadratic regression model. Both Ra and µH are influenced principally by the cutting speed and the feed rate. Model equations are found to predict accurate values of Ra and µH. Finally, desirability function approach for multiple response optimization is used to produce optimum SI.

A Study of the Impact of Workpiece Location on Machining Performance of a 2-DoF PKM Based Machine Tool

2013 ◽  
Author(s):  
A. B. Koteswara Rao ◽  
Sanjay Darvekar ◽  
K. Ramji
Keyword(s):  
Surface Roughness ◽  
End Milling ◽  
Structural Deformation ◽  
Quality Level ◽  
Machining Performance ◽  
Machined Surface ◽  
Milling Operations ◽  
Milling Operation ◽  
Tool Position ◽  
The Impact

This paper presents the impact of workpiece location on the machining performance of a 2-degree of freedom Parallel Kinematic Machine (PKM) tool. The PKM behavior is highly non-uniform and depends on the tool position within the workspace. The structural deformation and vibration due to cutting loads affect the quality of machined surfaces. The aim of the present study is to find the optimal tool position (workpiece location) where the workpiece is machined to a specific quality level. End-milling operations are carried out at various locations within the workspace and the surface roughness of machined surface (Ra) is measured at each location. A regression model is developed to predict the surface roughness. The study shows that the workpiece location has significant impact upon surface roughness of the machined part. Finally, a suitable workspace is defined for end-milling operation.

Plastic deformation and grain refinement in surface layer induced by thermo-mechanical loads for hard milling process

2018 ◽  
Vol 233 (10) ◽  
pp. 2033-2046 ◽  
Author(s):  
BinXun Li ◽  
Song Zhang ◽  
Jing Zhang
Keyword(s):  
Plastic Deformation ◽  
Grain Refinement ◽  
Surface Integrity ◽  
White Layer ◽  
Milling Process ◽  
Experimental Result ◽  
Plastic Deformation Zone ◽  
Hard Milling ◽  
Machined Surface ◽  
Mechanical Loads

Microstructure alteration of machined surface induced by the coupled thermal and mechanical loads in the hard milling process has great influence on surface integrity. Hence, it affects the performances of the workpiece. The hard milling experiments of AISI H13 steel with different cutting speeds and feed rates were carried out and the microstructure evolution of machined surface was investigated by means of some advanced characterization methods. The experimental result indicates that plastically deformed layer was evident with three distinguishable zones, that is, unaffected zone, plastic deformation zone, and white layer zone. X-ray diffraction analysis revealed that no retained austenite is detected in the white layer. Numerous nano-sized equiaxed grains were induced by dynamic recrystallization (DRX), as a result of severe shear plastic deformation on the machined surface. As the cutting speed increases, the grain refinement becomes more obvious. However, the original cementite was greatly refined and well distributed compared with bulk material. A significant improvement in nano-hardness was witnessed in both for machined surface and subsurface. The grain refinement as well as well-dispersed cementite played a vital role in the improvement of nano-hardness. The varied depth of plastic deformation was observed with respect to change of cutting forces. It is the main source of mechanical load inducing plastic deformation with the assistance of material thermal softening. The present work can provide more visibility on the surface integrity along with the quality control of the workpiece.

A Statistically Based Determination of the Depth of the Machining Affected Zone in Nickel-Based Superalloys Using MATLAB

2010 ◽  
Author(s):  
B. J. Richardson ◽  
Cristina Bunget ◽  
Thomas R. Kurfess
Keyword(s):  
Residual Stress ◽  
Surface Integrity ◽  
High Performance ◽  
Cutting Parameters ◽  
Subsurface Damage ◽  
Machined Surface ◽  
Sem Images ◽  
Critical Requirement ◽  
Scanning Electron

The surface integrity of a machined surface is a critical requirement in high performance applications such as gas turbine foils. Multiple aspects are incorporated in surface integrity, such as surface finish, changes in microstructure, and consequently residual stresses. This research focuses on detection of the presence of the subsurface damage and estimation of the depth of the damage, as related to the changes in microstructure. A statistically-based methodology for estimation of the depth of the machining affected zone (MAZ) using scanning electron microscope (SEM) images is developed and incorporated in MATLAB software, with the objective of having an automated and also more exact method than optical evaluation. The method is applied for estimation of the depth of the MAZ for nickel-based superalloys. The results of this work are being extended to correlate the MAZ with cutting parameters and conditions to determine the onset of subsurface damage, predict the extent of the MAZ and, ultimately, control its characteristics. Furthermore, this method can be extended for the analysis of different aspects of the microstructure (i.e., dimensions of grains) and estimating the amount of strain and residual stress in the damaged layer.

Analytical Cut Geometry Prediction for Free Form Surface During Semi-Finish Milling

2013 ◽  
Author(s):  
Hendriko ◽  
Emmanuel Duc ◽  
Gandjar Kiswanto
Keyword(s):  
Computational Time ◽  
Free Form ◽  
Depth Of Cut ◽  
Solid Model ◽  
Workpiece Surface ◽  
Engagement Angle ◽  
Rough Milling ◽  
Five Axis ◽  
Toroidal Cutter

In five-axis milling, determination of continuously changing Cutter Workpiece Engagement (CWE) is still a challenge. Solid model and discrete model are the most common method used to predict the engagement region. However, both methods are suffering with the long computational time. This paper presents an analytical method to define CWE of toroidal cutter during semi-finishing of sculpture part. The workpiece from 2.5D rough milling is represented by a number of blocks. The length of cut at every engagement angle can be determined by calculating the outermost engagement point called upper CWE point. This point was determined by first assumed that the workpiece surface is flat. A recalculation for CWE correction is then performed for the engagement occurred in two workpiece blocks. The method called Z-boundary and X-boundary are employed to obtain the upper CWE point when the engagement occurred on toroidal side. Meanwhile Cylinder-boundary method was used when the engagement occurred on the cylinder side. The developed model was examined to ensure its accuracy. A sculptured surface part was tested by comparing the depth of cut generated by the simulation developed and the depth of cut measured by Unigraphic. The result indicates that the proposed method is very accurate. Moreover, due to the method is analytically, and hence it is efficient in term of calculation time.

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