Multi-criteria optimization in end milling of AISI D2 hardened steel using coated carbide inserts

This paper proposes a multi-criteria optimization technique using the mathematical models developed by the response surface methodology (RSM) for the target responses combined with desirability indices for the determining the optimum cutting parameters in end milling of AISI D2 hardened steels. Different responses may require different targets either being maximized or minimized. Simultaneous achievement of the optimized (maximum or minimum) values of all the responses is very unlikely. In machining operations tool life and volume metal removed are targeted to be maximized whereas the machined surface roughness need to be at minimum level. Models showing the combined effect of the three control factors such as cutting speed, feed, and depth of cut are developed. However, a particular combination of parameter levels appears to be optimum for a particular response but not for all. Thus adoption of the method of consecutive searches with higher desirability values is found to be appropriate. In this study the desirability index reaches to a maximum value of 0.889 after five consecutive solution searching. At this stage, the optimum values of machining parameters - cutting speed, depth of cut and feed were determined as 44.27 m/min, 0.61 mm, 0.065 mm/tooth respectively. Under this set condition of machining operations a surface roughness of 0.348 μm and volume material removal of 7.45 cm3 were the best results compared to the rest four set conditions. However, the tool life would be required to compromise slightly from the optimum value

Development of mathematical cost model for room temperature end-milling of AISI D2 tool steel

In this research paper, reliable mathematical model for estimating the cost of room temperature end-milling of AISI D2 tool steel using TiAlN coated carbide tool inserts is developed. Initially, the different components of machining cost were identified, followed by establishment of equations to determine their values. Then, the required experimental and non-experimental data were collected and the bottom-up approach was adopted for evaluating the cost of machining corresponding to each of fifteen experimental runs. The Response Surface Methodology (RSM) was used to develop the model in which the cost of machining is given as a function of the machining parameters: cutting speed, feed per tooth, and depth of cut, and expressed in RM per cm3. ANOVA output was utilized to check the adequacy of the developed model. The developed model was found to be statistically adequate and this was confirmed by the small prediction errors made by the mode

Development of mathematical cost model for preheated end-milling of AISI D2 tool steel

Mohamed Elhadie1, A. N. Mustafizul Karim1, A. K. M. Nurul Amin1 Department of Manufacturing and Materials Engineering International Islamic University Malaysia, Gombak, Kuala Lumpur 53100, Malaysia M. A. Lajis2 Faculty of Mechanical and Manufacturing Engineering Universiti Tun Hussein Onn Malaysia, Batu Pahat, Johor Bahru 86400, Malaysia Abstract In this research paper, reliable mathematical model for estimating the cost of preheated end-milling of AISI D2 tool steel using TiAlN coated carbide tool inserts is developed. Initially, the different components of machining cost were identified, followed by establishment of equations to determine their values. Then, the required experimental and non-experimental data were collected and the bottom-up approach was adopted for evaluating the cost of machining corresponding to each of fifteen experimental runs. The Response Surface Methodology (RSM) was used to develop the model in which the cost of machining is given as a function of the machining parameters; cutting speed, feed per tooth, and preheating temperature, and expressed in RM per cm3. ANOVA output was utilized to check the adequacy of the developed model. The developed model was found to be statistically adequate and this was confirmed by the small prediction errors made by the model. Keywords: machinin

Preheating in end milling of AISI D2 hardened steel with coated carbide inserts

This study was conducted to investigate the effect of preheating through inductive heating mechanism in end milling of AISI D2 hardened steel (60-62 HRC) by using coated carbide tool inserts. Apart from preheating, two other machining parameters such as cutting speed and feed were varied while the depth of cut constant was kept constant. Tool wear phenomenon and machined surface finish were found to be significantly affected by preheating temperature and other two variables. End milling operation was performed on a Vertical Machining Centre (VMC). Preheating of the work material to a higher temperature range resulted in a noticeable reduction in tool wear rate leading to a longer tool life. In addition, improved surface finish was obtained with surface roughness values lower than 0.4 um, leaving a possibility of skipping the grinding and polishing operations for certain applications

Surface roughness models for end milling titanium alloy TI-6AL-4V under room temperature and preheated machining

This paper presents an approach in developing the first and second-order surface roughness models at 95% confidence level for end milling of titanium alloy Ti-6AI-4V using PCD inserts. The surface roughness models developed were for room temperature machining and preheated experiments. The cutting parameters for room temperature machining were the cutting speed, axial depth of cut, and feed while those for preheated machining experiments were cutting speed, feed, and preheating temperature. Vertical Machining Centre (VMC) was used for conducting the end milling operations using PCD inserts. High frequency induction heating was utilized for preheated experiments. Surface roughness values were measured using a surface roughness measuring instrument Mitutoyo Surftest Model SV-500. Design expert package software was used to establish the surface roughness models and the adequacy of the models were verified using analysis of variance at 95% of confidence interval

Surface roughness and surface integrity of end milled titanium alloy TI-6AL-4V at room temperature and preheated machining

This paper is concerned with the surface roughness and surface integrity of titanium alloy Ti- 6AI-4V after end milling under room temperature and preheated conditions. End milling experiments were carried out on a Vertical Machining Centre, using 20 mm uncoated WC-Co inserts. High frequency induction heating was utilized for preheated experiments. Surface roughness values were measured using a surface roughness measuring instrument Mitutoyo Surftest Model SV-500. The surface integrity and subsurface alteration were investigated by employing scanning electron microscope and Vickers micro-hardness. Prior to surface integrity inspections, the sample was cut with electro discharge wire cutting, then mounted using hot mounting, ground using silicon carbide papers, polished with alumina solution, and then etched with 10% HF, 5% HN03 and 85% H20 solutions. Microhardness was measured along the depth (perpendicular to the machined surface) at an interval of 0.01 mm starting from the top surface up and continued up to a depth of 0.5 mm. The results show that the surface layer could be divided into three zones, namely heat affected zone (Zone I), strain hardened zone (Zone II), and the base material (Zone III). A higher surface roughness achieved in preheated machining is attributed to the development of built-up edge (BUE) on the cutting tool surface

Tool Life Prediction by Response Surface Methodology for End Milling Titanium Alloy Ti-6Al-4V Using PCD Inserts

This paper presents an approach to establish models for tool life in end milling of titanium alloy Ti-6AI-4V using PCD inserts under dry conditions. Small central composite design (CCD) was employed in developing the tool life model in relation to primary cutting parameters such as cutting speed, axial depth of cut and feed. Flank wear has been considered as the criteria for tool failure and the wear was measured under a Hisomet II Toolmaker's microscope. Further testing was stopped and an insert rejected when an average flank wear greater than 0.30 mm was achieved. Design-expert version 6.0.8 software was applied to establish the first-order and the second-order models and develop the contours. The adequacy of the predictive model was verified using analysis of variance (ANOVA) at 95% confidence level

Theoretical and experimental investigation in prediction of tool life in preheated machining of AISI 02 hardened steel

The tool life of TiAlN coated carbide tools was investigated at various combinations of cutting speed, feed and preheating temperature in end milling of AISI 02 hardened steel under room temperature and preheated machining conditions. Sufficient number of experiments was conducted based on the central composite design (CCD) which was adopted by response surface methodology (RSM) to generate tool life prediction values. The experimental results show that preheated machining led to appreciable increasing tool life compared to room temperature machining. The percentage of tool life increase was between 190-315 % depending on preheating temperature. Preheating of the work material with higher heating temperatures (250-450 0c) gives significant improvement in terms of tool lif

Mechanical Properties of Direct Recycling Metal Matrix Composite (MMC-AlR) AA7075 Aircraft Aluminium Alloy

Recycling of aluminium aerospace alloys represents a major challenge to both the aluminium and aerospace industries. Ecological manageability in assembling is these days is a dire and exceptional issue and the principle concerns are identified with increasingly proficient utilization of energy and materials. Recycling allowed saving large amount greenhouse gas emission, particularly in the case of aluminium. Metal matrix composites spur the possibility of advancing typical monolithic material properties. Offering great strength, lightweight and being able to withstand high temperatures are the main behaviours of the metal matrix composite. To that extent, many practitioners in either automotive or aerospace industries employed metal matrix composite in most of the critical parts. Forming metal matrix composite via solid state processing is considered innovative, as most of the metal matrix composite forming process took place either in liquid or gaseous processing. An experimental investigation was conducted to investigate the mechanical properties of a recycled aluminium shifting alumina sum from 1 to 5 wt. % that had been presented to recycled aluminium chip employing hot press forging. Aluminium chip was obtained by milling AA7075-T1 bulk to a certain parameter. The medium size chips were cleaned, dried and mixed with alumina particles before being poured into a closed-die mould. The main responses investigated were ultimate tensile strength and elongation to failure and microstructure analysis. Out of all fractions, 4 wt. % of alumina shows the highest Ultimate tensile strength when the value increased from 155.214 MPa (1 wt. %) to 187.183 MPa. Further addition of alumina would enhance the composite strength, but in contrary, it also could prone the material performance

Prediction of surface roughness in hard milling of AISI D2 tool steel

This paper presents a study of the development of a surface roughness model in end milling of hardened steel AISI D2 using PVD TiAIN coated carbide cutting tool. The hardness of AISI D2 tool lies within the range of 56-58 HRe. The independent variables or the primary machining parameters selected for this experiment were the cutting speed, feed, and depth of cut. First and second order models were developed using Response Surface Methodology (RSM). Experiments were conducted within specified ranges of the parameters. Design-Expert 6.0 software was used to develop the surface roughness equations as the predictive models. Analysis of variance (ANOVA) with 95% confidence interval has indicated that the models are valid in predicting the surface roughness of the part machined under specified condition