An Experimental Study of Subcritical Bifurcations in Milling

2007 ◽  
Author(s):  
Anupam Radhakrishnan ◽  
Ben T. Edes ◽  
Brian P. Mann
Keyword(s):  
Periodic Solutions ◽  
Cutting Speed ◽  
Stable Solution ◽  
Stability Diagram ◽  
Depth Of Cut ◽  
Work Piece ◽  
Cutting Condition ◽  
Multiple Attractors ◽  
Stable Periodic ◽  
The Stability

The focus of the current paper is an experimental investigation of subcritical bifurcations in milling. Several researchers have reported results indicating that the secondary Hopf bifurcations of turning processes are subcritical. However, fewer results are available for milling — especially results that provide any substantial experimental evidence. Here, the experimental cutting tests were performed on a relatively long aluminum workpiece. The atypical length of the work piece will be used so that the depth of cut may be slowly increased or decreased during the cutting process. This provides visual evidence of hysteresis in the bifurcation diagram and the existence of multiple stable periodic solutions. The importance of this exploratory experimental effort is that multiple attractors may co-exist (stable periodic solutions) for the same cutting speed and depth of cut, but only one of these solutions would be the chatter free case. An important outcome from these results is that a small perturbation in the desirable stable solution near the borders of the stability diagram could result in a jump to the unstable cutting condition.

Effects of Process Parameters on Surface Roughness and MRR in the hard turning of EN 36 steel

2018 ◽  
pp. 102-110
Author(s):  
Amritpal Singh ◽  
Rakesh Kumar
Keyword(s):  
Surface Roughness ◽  
Material Removal Rate ◽  
Material Removal ◽  
Hard Turning ◽  
Control Parameter ◽  
Removal Rate ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Dry Cutting

In the present study, Experimental investigation of the effects of various cutting parameters on the response parameters in the hard turning of EN36 steel under the dry cutting condition is done. The input control parameters selected for the present work was the cutting speed, feed and depth of cut. The objective of the present work is to minimize the surface roughness to obtain better surface finish and maximization of material removal rate for better productivity. The design of experiments was done with the help of Taguchi L9 orthogonal array. Analysis of variance (ANOVA) was used to find out the significance of the input parameters on the response parameters. Percentage contribution for each control parameter was calculated using ANOVA with 95 % confidence value. From results, it was observed that feed is the most significant factor for surface roughness and the depth of cut is the most significant control parameter for Material removal rate.

Modeling and Optimization of Vibration Amplitude in Turning of Ti-6Al-4V Using Response Surface Methodology

2012 ◽  
Vol 217-219 ◽  
pp. 1567-1570
Author(s):  
A.K.M. Nurul Amin ◽  
Muammer Din Arif ◽  
Syidatul Akma Sulaiman
Keyword(s):  
Response Surface Methodology ◽  
Response Surface ◽  
Vibration Amplitude ◽  
Desirability Function ◽  
Cutting Speed ◽  
Vibration Sensor ◽  
Experimental Investigations ◽  
Depth Of Cut ◽  
Work Piece ◽  
Inferior Surface

Chatter is detrimental to turning operations and leads to inferior surface topography, reduced productivity, dimensional accuracy, and shortened tool life. Avoidance of chatter has mostly been through reliance on heuristics such as: limiting material removal rates or selecting low spindle speeds and shallow depth of cuts. But, modern industries demand increased output and not steady operational limits. Various research efforts have therefore focused on developing mathematical models for chatter formation. However, as yet there is no existent model that meets all experimental verification. This research employed a novel technique based on the synergy of statistical modeling and experimental investigations in order to develop an effective empirical mathematical model for chatter amplitude and to subsequently find optimal machining conditions. Ti-6Al-4V, Titanium alloy, was used as the work-piece due to its increased popularity in applications related to aerospace, automotive, nuclear, medical, marine etc. A sequence of 15 experimental runs was conducted based on a small Central Composite Design (CCD) model in Response Surface Methodology (RSM). The primary (independent) parameters were: cutting speed, feed, and depth of cut. The tool overhang was kept constant at 70 mm. An engine lathe (Harrison M390) was employed for turning purposes. The data acquisition system comprised a vibration sensor (accelerometer) and a signal conditioning unit. The resultant vibrations were analyzed using the DASYLab 5.6 software. The best model was found to be quadratic which had a confidence level of 95% (ANOVA) and insignificant Lack of Fit (LOF) in Fit and Summary analyses. Desirability Function (DF) approach predicted minimum vibration amplitude of 0.0276 Volts and overlay plots identified two preferred machining regimes for optimal vibration amplitude.

Experimental Determination of Optimal Speeds for Alloy Steels in Plane Turning

2008 ◽  
Author(s):  
T. Srikanth ◽  
V. Kamala
Keyword(s):  
Surface Roughness ◽  
Force Measurement ◽  
Cutting Speed ◽  
Vital Role ◽  
The Other ◽  
Depth Of Cut ◽  
Work Piece ◽  
Material Interface ◽  
Alloy Steels

In machining, speeds play vital role. The operator should know exactly the speed at which machining should be performed to get the required surface finish. In this paper, an attempt is made to determine the optimal cutting speed for machining of alloy steels. Three work piece materials having different hardness are taken and machined using a round nose tool with a coated tip. The tool dynamometer is attached to the tool post for force measurement. Turning operation on the work piece is performed on lathe at four different speeds, keeping the feed and depth of cut constant. Cutting forces acting on the tool, temperature at the tool and material interface are recorded. Power consumed being determined by a wattmeter and surface roughness values are measured. The same procedure is repeated for the other two work-pieces materials and optimal speeds for machining are determined for the three specimens. The results obtained are compared with the theoretical values and found to be very close.

Hopf Bifurcation Induced by Delay Effect in a Diffusive Tumor-Immune System

2018 ◽  
Vol 28 (11) ◽  
pp. 1850136 ◽  
Author(s):  
Ben Niu ◽  
Yuxiao Guo ◽  
Yanfei Du
Keyword(s):  
Immune System ◽  
Hopf Bifurcation ◽  
Periodic Solutions ◽  
Center Manifold ◽  
Immune Cell ◽  
Tumor Treatment ◽  
Delay Effect ◽  
Stable Periodic ◽  
The Stability ◽  
Bifurcation And Stability

Tumor-immune interaction plays an important role in the tumor treatment. We analyze the stability of steady states in a diffusive tumor-immune model with response and proliferation delay [Formula: see text] of immune system where the immune cell has a probability [Formula: see text] in killing tumor cells. We find increasing time delay [Formula: see text] destabilizes the positive steady state and induces Hopf bifurcations. The criticality of Hopf bifurcation is investigated by deriving normal forms on the center manifold, then the direction of bifurcation and stability of bifurcating periodic solutions are determined. Using a group of parameters to simulate the system, stable periodic solutions are found near the Hopf bifurcation. The effect of killing probability [Formula: see text] on Hopf bifurcation values is also discussed.

Performance assessment of energy efficient and eco-friendly turning of Nimonic C-263: A comparative study on MQL and cryogenic machining

2021 ◽  
pp. 095440542110619
Author(s):  
Prashant S Jadhav ◽  
Chinmaya P Mohanty
Keyword(s):  
Work Environment ◽  
Manufacturing Industry ◽  
Cutting Speed ◽  
Machining Process ◽  
Depth Of Cut ◽  
Work Piece ◽  
Cryogenic Machining ◽  
Machined Surface ◽  
Machining Strategies ◽  
The Impact

Nimonic C-263 is predominantly used in the manufacturing of heat susceptible intricate components in the gas turbine, aircraft, and automotive industries. Owing to its high strength, poor thermal conductivity, the superalloy is difficult to machine and causes rapid tool wear during conventional machining mode. Moreover, the unpleasant machining noise produced during machining severely disrupts the tool engineer’s concentration, thereby denying a precise and environment friendly machining operation. Hence, close dimensional accuracy, superior machined surface quality along with production economy, and pleasant work environment for the tool engineers is the need of an hour of the current manufacturing industry. To counter such issues, the present work attempts to compare and explore the machinability of two of the most popular machining strategies like minimum quantity lubrication (MQL) and cryogenic machining process during turning of Nimonic C-263 work piece in order to achieve an ideal machining environment. The machining characteristics are compared in terms of surface roughness (SR), power consumption (P), machining noise (S), nose wear (NW), and cutting forces (CF) to evaluate the impact of machining variables like cutting speed (Vc), feed (f), and depth of cut (ap) with a detailed parametric study and technical justification. Yet again, an investigation is conducted to compare both the machining strategies in terms of qualitative responses like chip morphology, total machining cost, and carbon emissions. The study revealed that cryogenic machining strategy is adequately proficient over MQL machining to deliver energy proficient and gratifying work environment for the tool engineers by reducing the cost of machining and improving their work efficiency.

Multi-criteria optimization and predictive modeling of turning forces in high-speed machining of yttria based zirconia toughened alumina insert using desirability function approach

2015 ◽  
Vol 231 (8) ◽  
pp. 1396-1408 ◽  
Author(s):  
Nilrudra Mandal ◽  
B Doloi ◽  
Biswanath Mondal ◽  
BK Singh
Keyword(s):  
Feed Rate ◽  
High Speed ◽  
Desirability Function ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Machining Forces ◽  
Feed Force ◽  
Response Optimization ◽  
Zirconia Toughened Alumina

An attempt has been made to apply the Taguchi parameter design method and multi-response optimization using desirability analysis for optimizing the cutting conditions (cutting speed, feed rate and depth of cut) on machining forces while finish turning of AISI 4340 steel using developed yttria based zirconia toughened alumina inserts. These zirconia toughened alumina inserts were prepared through wet chemical co-precipitation route followed by powder metallurgy process. The L9 (4) orthogonal array of the Taguchi experiment is selected for three major parameters, and based on the mean response and signal-to-noise ratio of measured machining forces, the optimal cutting condition arrived for feed force is A1, B1 and C3 (cutting speed: 150 m/min, depth of cut: 0.5 mm and feed rate: 0.28 mm/rev) and for thrust and cutting forces is A3, B1 and C1 (cutting speed: 350 m/min, depth of cut: 0.5 mm and feed rate: 0.18 mm/rev) considering the smaller-the-better approach. Multi-response optimization using desirability function has been applied to minimize each response, that is, machining forces, simultaneously by setting a goal of highest cutting speed and feed rate criteria. From this study, it can be concluded that the optimum parameters can be set at cutting speed of 350 m/min, depth of cut of 0.5 mm and feed rate of 0.25 mm/rev for minimizing the forces with 78% desirability level.

Identification of Optimum Heating Temperature in Thermal Assisted Turning of Stainless Steel Using Three Different Approaches

2013 ◽  
Vol 393 ◽  
pp. 194-199 ◽  
Author(s):  
A.K.M. Nurul Amin ◽  
Muammer Din Arif ◽  
Noor Hawa B. Mohamad Rasdi ◽  
Khairus Syakirah B. Mahmud ◽  
Abdul Hakam B. Ibrahim ◽  
...  
Keyword(s):  
Stainless Steel ◽  
Heating Temperature ◽  
Cutting Temperature ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
304 Stainless Steel ◽  
Depth Of Cut ◽  
Work Piece ◽  
Optimum Temperature ◽  
Main Concept

Thermal or heat assisted machining is used to machine hard and difficult-to-machine materials such as Inconel and Titanium alloys. The main concept is that localized surface heating of the work-piece reduces the yield strength of the material significantly, making it amenable to plastic deformation and machining. Thus, heat assisted machining has been used for over a century. However, the heating technique and temperature are very much dependent on the type of working material. Therefore, a multitude of heating techniques has been applied over the years including Laser Assisted Machining (LAM) and Plasma Enhanced Machining (PEM) in the industry. But such processes are very expensive and have not been found in wide scale applications. The authors of the current research have therefore looked into the application of a simple Tungsten Inert Gas (TIG) welding setup to perform heat assisted turning of AISI 304 Stainless Steel. Such welding equipment is relatively cheap and available. Also, stainless steel is perennially used in the industry for high strength applications. Hence, it is very important to determine with optimal cutting temperature when applying a TIG setup for heat assisted machining of stainless steel. This paper describes three separate techniques for determining the optimum temperature. All three processes applied the same experimental setup but used different variables for evaluating the best temperature. The first process used vibration amplitude reduction with increment in temperature to identify the desired temperature. The second process used chip shrinkage coefficient to locate the same temperature. And finally, the third process investigated tool wear as a criterion for determining the optimum temperature. In all three cases the three primary cutting parameters: cutting speed, feed, and depth of cut, were varied in the same pattern. The results obtained from all three approaches showed that 450oC was undoubtedly the best temperature for heat assisted machining of stainless steel.

Life Prediction of Cutting Tool by the Workpiece Cutting Condition

2011 ◽  
Vol 223 ◽  
pp. 554-563 ◽  
Author(s):  
Noemia Gomes de Mattos de Mesquita ◽  
José Eduardo Ferreira de Oliveira ◽  
Arimatea Quaresma Ferraz
Keyword(s):  
Cutting Tool ◽  
Cutting Tools ◽  
Cutting Speed ◽  
Cutting Parameters ◽  
Operating Conditions ◽  
Production Costs ◽  
Depth Of Cut ◽  
Cutting Condition ◽  
Workpiece Material ◽  
The Cost

Stops to exchange cutting tool, to set up again the tool in a turning operation with CNC or to measure the workpiece dimensions have direct influence on production. The premature removal of the cutting tool results in high cost of machining, since the parcel relating to the cost of the cutting tool increases. On the other hand the late exchange of cutting tool also increases the cost of production because getting parts out of the preset tolerances may require rework for its use, when it does not cause bigger problems such as breaking of cutting tools or the loss of the part. Therefore, the right time to exchange the tool should be well defined when wanted to minimize production costs. When the flank wear is the limiting tool life, the time predetermination that a cutting tool must be used for the machining occurs within the limits of tolerance can be done without difficulty. This paper aims to show how the life of the cutting tool can be calculated taking into account the cutting parameters (cutting speed, feed and depth of cut), workpiece material, power of the machine, the dimensional tolerance of the part, the finishing surface, the geometry of the cutting tool and operating conditions of the machine tool, once known the parameters of Taylor algebraic structure. These parameters were raised for the ABNT 1038 steel machined with cutting tools of hard metal.

Effects of Cutting Condition on Surface Roughness when Turning Untreated and Sb-Treated Al-11%Si Alloys Using PVD Coated Tools

2013 ◽  
Vol 315 ◽  
pp. 413-417 ◽  
Author(s):  
Mohsen Marani Barzani ◽  
Mohd Yusof Noordin ◽  
Ali Akhavan Farid ◽  
Saaed Farahany ◽  
Ali Davoudinejad
Keyword(s):  
Surface Roughness ◽  
Cutting Speed ◽  
Depth Of Cut ◽  
Manufacturing Processes ◽  
Cutting Condition ◽  
Dry Cutting ◽  
Fabrication Cost ◽  
Coated Tools ◽  
Experimental Trials ◽  
Cutting Speeds

Surface roughness is an important output in different manufacturing processes. Its characteristic affects directly the performance of mechanical components and the fabrication cost. In this current work, an experimental investigation was conducted to determine the effects of various cutting speeds and feed rates on surface roughness in turning the untreated and Sb-treated Al-11%Si alloys. Experimental trials carried out using PVD TIN coated inserts. Experiments accomplished under oblique dry cutting when three different cutting speeds have been used at 70, 130 and 250 m/min with feed rates of 0.05, 0.1 and 0.15 mm/rev, whereas depth of cut kept constant at 0.05 mm. The results showed that Sb-treated Al-11%Si alloys have poor surface roughness in comparison to untreated Al-11%Si alloy. The surface roughness values reduce with cutting speed increment from 70 m/min to 250 m/min. Also, the surface finish deteriorated with increase in feed rate from 0.5 mm/rev to 0.15 mm/rev.

Evaluation of Cutting Rate for Ultrasonic Work Piece Vibration Assisted Wire-EDM under Varying Amplitude of Vibration

2020 ◽  
Vol 979 ◽  
pp. 149-156
Author(s):  
Sanjay Kumar ◽  
Sandeep Grover ◽  
Ravinder S. Walia
Keyword(s):  
Cutting Speed ◽  
Work Piece ◽  
Cutting Condition ◽  
Time Level ◽  
Peak Current ◽  
Optimum Cutting ◽  
Pulse On Time ◽  
Pulse Off Time ◽  
Off Time ◽  
Level 2

This paper present an investigation on cutting speed of ultrasonic vibration assisted wire electrical discharge machining (US-WEDM) for High carbon high chromium D3 Steel. An extensive research study was carried out with an aim to select the optimum cutting condition with the varying amplitude of vibration in order to get the optimum cutting speed for the proposed set-up. The process was mathematically modeled using the response parameters, i.e. cutting speed under a range of control parameters and the main influencing factors were determined for cutting speed criteria Taguchi’s experimentation methodology indicated the contribution of amplitude of vibration (P=6.16%), pulse on time (P=14.54%), pulse off time (P=73.16%) and peak current (P=5.94%). Finally, the optimum parametric setting for different cutting speed arising out of study has synthesized as amplitude of vibration at level 3 (18μm), peak current level 1 (100 units), pulse on time level 2 (118 μ sec) and pulse off time level 2 (46 μ sec) and analyses in this study.

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