scholarly journals Chatter Vibration Comparison Between Normal Helix Angle and Variable Helix Angle in End Milling Process Based on Spectrum Analysis

2020 ◽  
Vol 11 (3) ◽  
pp. 531-536
Author(s):  
Achmad As'ad Sonief ◽  
◽  
Arda Nur Fauzan ◽  
Fachry Azlan ◽  
Muhammad Aziz Bashori
Keyword(s):  
Spectrum Analysis ◽  
Cutting Tool ◽  
End Milling ◽  
Helix Angle ◽  
Depth Of Cut ◽  
Chatter Vibration ◽  
Machining Processes ◽  
Chatter Vibrations ◽  
Excited Vibration ◽  
Variable Helix

Chatter vibration in machining processes is often found in cutting processes which will decrease the machining efficiency and the surface quality of the products. Chatter is a relative vibration of the cutting tool and workpiece caused by the fluctuation of cutting force that is concerned to be a self-excited vibration. The variable Helix Angle Cutting tool which has pitch angle variation will also inflict different tooth passing frequencies on the flute that stand contiguous and trim the resonance frequency. This research aims to compare chatter vibrations that occurred between Normal Helix Angle and Variable Helix Angle cutting tool based on spectrum analysis on cutting parameter variety (depth of cut; rotation speed; feed rate milling). The outcome is spectrum analysis can detect the chatter phenomenon, measure the natural frequency (38-42 Hz), and also compare chatter vibrations between two tools appropriately.

scholarly journals Pengaruh Geometri Pahat Variabel Helix Angle Pada Parameter Mesin Cnc Milling Vertikal Berbasis Mikrokontroler Terhadap Nilai Getaran Chatter

2020 ◽  
Vol 1 (2) ◽  
pp. 62-71
Author(s):  
Festo Andre Hardinsi ◽  
Oyong Novareza ◽  
Achmad As’ad Sonief
Keyword(s):  
Feed Rate ◽  
Helix Angle ◽  
Machining Process ◽  
Depth Of Cut ◽  
Cnc Milling ◽  
Chatter Vibration ◽  
Vibration Acceleration ◽  
Slot Milling ◽  
Excited Vibration ◽  
Variable Helix

Abstrak Objektif. Getaran yang sering terjadi pada pengerjaan proses produksi menggunakan permesinan CNC milling merupakan hal yang sangat penting untuk diperhitungkan. Getaran ini dapat menyebabkan perubahan dimensi dan mempengaruhi tingkat kualitas benda kerja yang dihasilkan, sehingga efek getaran chatter atau self-excited vibration  pada proses pengerjaan produksi menjadi masalah utama dalam proses permesinan milling. Nilai getaran chatter ditentukan menggunakan grafik SLD secara ekperimental untuk mengetahui batas antara chatter free dan chatter occurs. Material and Metode. Material yang digunakan dalam penelitian ini adalah Stanless steel 304, dengan menggunakan sensor MPU 6050 yang terhubung pada mikrokontroler Arduino Uno menggunakan software LabVIEW 2019 student edition yang digunakan untuk mengidentifikasi nilai acceleration getaran chatter. Besar nilai acceleration diukur menggunakan FFT menggunakan software DIAdem 2019 student. Metode yang digunakan dalam penelitian ini adalah dalam bentuk eksperimental, dengan geometri pahat Variabel Helix Angle (VHA) 2 variasi sudut yaitu 40/42 (Derajat), Spindel Speed sebesar 2000,2500,3000 (RPM) , Axial Depth Of Cut sebesar 0.5, 1.0, 1.5 (mm), dan Feed Rate sebesar 100, 125 dan 150 (mm/s). Hasil. Hasil pada Grafik Stability Lobe Diagram yang didapatkan pada proses permesinan slot milling menggunakan pahat variable helix angle 40/42 derajat dengan feed rate 150 mm/mnt memiliki  chatter free yang lebih tinggi dibandingkan dengan feed rate 100 dan 125 mm/mnt. Kesimpulan.  Dari hasil yang didapatkan bahwa semakin tinggi nilai feed rate maka nilai acceleration getaran chatter semakin rendah. Untuk pengembangan dalam penelitian selanjutkan maka perlu dilakukan pemilihan parameter geometri pahat dengan variasi 3 sudut mata pahat untuk mengetahui nilai getaran chatter yang signifikan. Abstrack Objective.Vibration that often occurs in the production process using CNC milling is very important to be taken into account. This is vibration can cause dimensional changes and affect the level of quality of the workpiece produced. Therefore, effect of chatter vibration or self-excited vibration on production process becomes a major problem in the milling machining process. Chatter vibration values ​​can be determined using experimental SLD for determine boundary between free chatter and chatter occur. Materials and Methods .The material used in this study is stanless steel 304, using the MPU 6050 sensor connected to Arduino Uno mikrokontroler using LabVIEW 2019 student edition software that is used to identify chatter vibration acceleration. Acceleration is measured using FFT using  2019 student DIAdem software. The method used is experimental, geometry Variable Helix Angle 2 angular 40/42 (Degrees), Spindel Speed ​​of 2000,2500,3000 (RPM), Axial Depth Of Cut of 0.5, 1.0, 1.5 (mm), and Feed Rate of 100, 125 and 150 (mm / s). Results. Results in the Graph Lobe Stability Diagram obtained in  slot milling machining process using a variable helix angle of 40/42 degrees with  feed rate of 150 mm / min have higher chatter free compared to feed rates of 100 and 125 mm / min. Conclusion. The results show that  higher the value of  feed rate, chatter vibration acceleration value is lower. For further development in research, it is necessary to select  tool geometry parameters with variations of 3 tool eye angle to determine  chatter vibration significant

Investigation of Chatter Vibration in End-Milling Process by Considering Coupled System Model

2014 ◽  
Vol 939 ◽  
pp. 201-208
Author(s):  
Kosuke Hattori ◽  
Hiroyuki Kodama ◽  
Toshiki Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Cutting Tool ◽  
End Milling ◽  
Milling Process ◽  
Work Piece ◽  
Vibration Modes ◽  
Test Results ◽  
Chatter Vibration ◽  
Simple Method ◽  
Excited Vibration ◽  
End Milling Process

Chatter vibration in cutting processes usually leads to surface finish degradation, tool damage, cutting noise, energy loss, etc. Self-excited vibration particularly seems to be a problem that is easily increased to large vibration. The regenerative effect is considered as one of the causes of chatter vibration. Although the chatter vibration occurs in various types of processing, the end-milling is a typical process that seems to cause the chatter vibration due to a lack of rigidity of one or more parts of the machine tools, cutting tool, and work-piece. The aim of our research is to propose a simple method to control chatter vibration of the end-milling process on the basis of a coupling model integrating the related various elements. In this study, hammering tests were carried out to measure the transfer function of a machine tool and cutting tool system, which seems to cause vibration. By comparing these results, finite elemental method (FEM) analysis models were constructed. Additionally, cutting experiments were carried out to confirm the chatter vibration frequencies in end-milling with a machining center. In the hammering tests, impulse hammer and multiple acceleration pick-ups are connected to a multi-channel FFT analyzer and estimate the natural frequencies and natural vibration modes. A simplified FEM model is proposed by circular section stepped beam elements on the basis of the hammering test results, considering a coupling effect. In comparisons of the calculated results and hammering test results, the vibration modes are in good agreement. As a result, the proposed model accurately predicts the chatter vibration considering several effects among the relating elements in end-milling. Moreover, it can be seen that the chatter vibration is investigated from a viewpoint of the integrating model of the end-milling process.

scholarly journals OPTIMIZATION OF VARIABEL HELIX ANGLE PARAMETERS IN CNC MILLING OF CHATTER AND SURFACE ROUGHNES USING TAGUCHI METHOD

2021 ◽  
Vol 9 (1) ◽  
pp. 35-44
Author(s):  
Festo Andre Hardinsi ◽  
◽  
Oyong Novareza ◽  
Achmad As'ad Sonief
Keyword(s):  
Surface Roughness ◽  
Taguchi Method ◽  
Feed Rate ◽  
Helix Angle ◽  
Spindle Speed ◽  
Depth Of Cut ◽  
Cnc Milling ◽  
Excited Vibration ◽  
Optimal Value ◽  
Variable Helix

In the manufacturing industries, the main problem in process of operating CNC milling machine was chatter effect (self-excited vibration) which increases the quality of the surface roughness. In this study is to determine optimal value of parameters for chatter and surface roughness. The chatter measured using accelerometer MPU-6050 with Arduino by software LabVIEW-2019 based on peaks-FFT value and the surface roughness measured by SJ-301 tester. The research parameters like variable helix angle, spindle speed, feed rate, and depth of cut using stainless steel 304 by Taguchi method. The optimum parameters value obtained are variable helix 35/38 degrees, spindle speed 3000 RPM, feed rate 150 mm/min and depth of cut 0.4 mm. Based on ANOVA value, the variable helix angle and depth of cut are found to be significant for chatter and surface roughness. The depth of cut was high contribution by ANOVA chatter by 93.84% and surface roughness by 91.93%.

scholarly journals Experimental Verification of Chatter-Free Ball End Milling Strategy

2013 ◽  
Vol 7 (1) ◽  
pp. 45-51 ◽  
Author(s):  
Lin Lu ◽  
◽  
Masahiko Sato ◽  
Hisataka Tanaka ◽  
Keyword(s):  
Cutting Tool ◽  
End Milling ◽  
Cutting Parameters ◽  
Cutting Condition ◽  
Chatter Stability ◽  
Chatter Vibration ◽  
Ball End Milling ◽  
Machining Center ◽  
Avoidance Control ◽  
Avoidance Strategy

Chatter vibration frequently occurs in ball end milling. If the characteristics of the cutting tool system and cutting process are known, chatter stability in ball end milling can be evaluated. Hence, in this paper, a chatter-avoidance strategy based on a regenerative chatter theory is proposed to prevent the occurrence of chatter. This consists of a simulation of chatter stability and cutting condition control. When the characteristics of a vibration system change, this chatter-avoidance strategy cannot cope with it. Therefore, another chatter-avoidance control algorism that changes cutting parameters on a machining center is proposed. This can adapt to the change in the characteristics of the vibration systemduring cutting. The effectiveness of the two chatter-avoidance methods proposed is examined through experiments.

Variable Helix Cutter Design to Suppress Regenerative Effect

2019 ◽  
Author(s):  
Norikazu Suzuki ◽  
Rikiya Ishiguro ◽  
Tomoki Morita ◽  
Eiji Shamoto
Keyword(s):  
Design Methodology ◽  
Design Method ◽  
Simultaneous Optimization ◽  
Axial Position ◽  
Depth Of Cut ◽  
Chatter Vibration ◽  
Major Mechanism ◽  
Variable Helix ◽  
Cutter Design ◽  
Regeneration Factor

Abstract Regeneration is a major mechanism to generate self-excited chatter vibration in cutting. Variable helix cutters are useful to suppress regeneration. Although simultaneous optimization of pitch/helix angles is significantly important, there is no practical design methodology to optimize the variable helix cutter geometry so far. In order to attain robust regeneration suppression, a new design method of variable helix cutters is proposed in the present study. The pitch angles vary along axial position due to disagreement of the helix angles. Because of this nature, regeneration can be suppressed in a robust manner with respect to changes of chatter frequency and/or spindle speed. The proposed design satisfies robustness against axial depth of cut variations. Optimal pitch/helix angles are formulated on the basis of distinctive relationship between the cutter geometry and “Regeneration Factor (RF)”, which is an index to quantify influence of regeneration in the process. Through analytical investigations, it is confirmed that regeneration can be suppressed effectively by the proposed method, resulting in significant chatter stability increase. Low immersion milling experiment verified significant stability and robustness of the proposed variable helix design.

Assessment of the Cutting Tooling Effect on Turning Chatter

2013 ◽  
Vol 433-435 ◽  
pp. 2101-2106
Author(s):  
Joon Hwang ◽  
Ey Hyoun Jeong ◽  
Eui Sik Chung ◽  
Steven Y. Liang
Keyword(s):  
Cutting Forces ◽  
Cutting Speed ◽  
Tool Geometry ◽  
Depth Of Cut ◽  
Nonlinear Phenomenon ◽  
Chatter Vibration ◽  
Machining Performance ◽  
Dynamic Component ◽  
Excited Vibration ◽  
Overhang Length

Machining performance is often limited by chatter vibration at the tool-workpiece interface. Chatter is a type of machining self-excited vibration which originates from the variation in cutting forces and the flexibility of the machine tool structure. Machining chatter is an inherently nonlinear phenomenon that is affected by many parameters such as cutting conditions, tool geometry, cutting speed, feed rate, depth of cut, overhang length of tool, clamping condition of workpiece. This study presents experimental approach for investigation of effects of various cutting tool geometry on the onset of chatter. In turning process, measured cutting force signal and triaxial accelerometer signal was used to know the characteristics of chatter vibration. The static and dynamic component of cutting forces reflect onset of chatter vibration. Proper selection of tooling is an important parameter in terms of chatter elimination in machining.

Chatter Investigation in Titanium Milling

2014 ◽  
Vol 1019 ◽  
pp. 318-324
Author(s):  
Jean Claude Fwamba ◽  
Lerato Crescelda Tshabalala ◽  
Cebo Philani Ntuli ◽  
Isaac Tlhabadira
Keyword(s):  
Feed Rate ◽  
End Milling ◽  
Processing Condition ◽  
Weight Ratio ◽  
Dimensional Accuracy ◽  
Milling Process ◽  
Machining Process ◽  
Depth Of Cut ◽  
Machining Performance ◽  
Chatter Vibrations

<span><p align="LEFT"><span><span style="font-family: Times New Roman;" face="Times New Roman">Titanium and its alloys have been experiencing extensive development over the past few decades. They have found wide applications in the aerospace, biomedical and automotive industries owing to their good strength-to-weight ratio and high corrosion resistance. Machining performance is often limited by chatter vibrations at the tool-workpiece interface. Chatter is an abnormal tool behaviour which is one of the most critical problems in the machining process and must be avoided to improve the dimensional accuracy and surface quality of the finished product. This research aims at investigating chatter trends in the end milling process and to identify machine parameters that have effects on chatter during machining. The machine parameters investigated include axial feed rate, spindle revolute speed and depth of cut. In this research, experimental data was collected using sensors to analyze the existence of chatter vibrations on each processing condition. This research showed that the combination of the machine parameters, feed rate and spindle speed within certain proportions has an influence on machine vibrations during end milling and if not managed properly, may lead to chatter. </span></span></p> <p align="LEFT"></p>

Stability prediction of milling process with variable pitch and variable helix cutters

2013 ◽  
Vol 228 (2) ◽  
pp. 281-293 ◽  
Author(s):  
Gang Jin ◽  
Qichang Zhang ◽  
Shuying Hao ◽  
Qizhi Xie
Keyword(s):  
Helix Angle ◽  
Milling Process ◽  
Force Model ◽  
Stability Prediction ◽  
Chatter Vibration ◽  
Variable Pitch ◽  
Tool Geometries ◽  
Variable Helix ◽  
Piecewise Continuous ◽  
The Stability

The use of variable pitch or helix cutters is a known means to prevent chatter vibration during milling. In this article, an alternative method based on an improved semi-discretization method is proposed to predict the stability of variable pitch or variable helix milling. In order to consider the effect of distributed system delays attributed to helix variation, the average delays were calculated for each flute after the engaged cutting flutes were divided into a finite number of axial elements. Meanwhile, a straightforward integral force model, which can consider the piecewise continuous regions of the cutting that describe the helix angle is used to determine the cutting force. Through comparisons with prior works, time-domain simulations, and cutting tests, the proposed approach was verified. In addition, the method was applied to examine the effect of tool geometries on stability trends. Several phenomena for certain combinations of pitch and helix angles are shown and explained.

scholarly journals Effect of Carbon Fiber Orientation and Helix Angle on CFRP Cutting Characteristics by End-Milling

2013 ◽  
Vol 7 (3) ◽  
pp. 292-299 ◽  
Author(s):  
Masahiro Hagino ◽  
◽  
Takashi Inoue ◽  
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Surface Finish ◽  
Fiber Orientation ◽  
End Milling ◽  
Cutting Speed ◽  
Helix Angle ◽  
Depth Of Cut ◽  
Reinforced Plastics ◽  
End Mills

Carbon Fiber Reinforced Plastics (CFRP) have outstanding lightweight material characteristics and tensile strength. The use of CFRP in aerospace industry has been successfully implemented and is expected to grow in the future. However, the mechanical properties of CFRP are affected by differences in the distribution and orientation of the carbon fibers and their adhesion to the binding material. CFRP shows intense anisotropy in strength of carbon fiber depending on its mechanical properties and the state of the carbon fiber orientation. Therefore, the tool life shortest and the surface finish quality of the material becomes unstable and eventually difficult to cut. This paper presents the effect on carbon fiber orientation and helix angle with CFRP cutting characteristics by end milling. Here, three types of orientations weremachined by straight type end mills and constant cutting conditions with a cutting speed 70 m/min, a feed rate 0.056 mm/tooth and 3 mm depth of cut. Our results showed that the tool helix angle 0° gave a better surface finish than the other tools, irrespective of the fiber orientation. The helix angle is greatly affected by the exposure of the fibers from the surface. Axial force (Fz) is negligible quantity for helix angle 0°, and cutting force is low. The carbon fiber orientation of 45° and -45° has exfoliation-like dimples.

scholarly journals Machining Process for a Thin-Walled Workpiece Using On-Machine Measurement of the Workpiece Compliance

2019 ◽  
Vol 13 (5) ◽  
pp. 631-638 ◽  
Author(s):  
Takuma Umezu ◽  
◽  
Daisuke Kono
Keyword(s):  
Measurement System ◽  
End Milling ◽  
Numerical Control ◽  
Cutting Conditions ◽  
Machining Process ◽  
Experimental Result ◽  
Depth Of Cut ◽  
Machining Processes ◽  
Workpiece Vibration ◽  
Thin Walled

Demand for highly productive machining of thin-walled workpieces has been growing in the aerospace industry. Workpiece vibration is a critical issue that could limit the productivity of such machining processes. This study proposes a machining process for thin-walled workpieces that aims to reduce the workpiece vibration during the machining process. The workpiece compliance is measured using an on-machine measurement system to obtain the cutting conditions and utilize the same for suppressing the vibration. The on-machine measurement system consists of a shaker with a force sensor attached on the machine tool spindle, and an excitation control system which is incorporated within the machine tool’s numerical control (NC). A separate sensor to obtain the workpiece displacement is not required for the estimation of the displacement. The system is also capable of automatic measurement at various measurement points because the NC controls the positioning and the preloading of the shaker. The amplitude of the workpiece vibration is simulated using the measured compliance to obtain the cutting conditions for suppressing the vibration. An end milling experiment was conducted to verify the validity of the proposed process. The simulations with the compliance measurement using the developed system were compared to the results of a conventional impact test. The comparison showed that the spindle rotation speed for suppressing the vibration could be successfully determined; but, the axial depth of cut was difficult to be determined because the simulated vibration amplitude was larger than that found in the experimental result. However, this can be achieved if the amplitude is calibrated by one machining trial.

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