Effect of Heating Temperature, Holding Time and Stabilization Temperature on the Al-Foam Properties

The interest in metallic foam is increasing since their cellular structures have a unique combination of properties such as high stiffness, low density, lightweight, high specific strength, and thermal insulation. Commonly, the performance of metallic foam can be improved by the heat treatment process. However, the previous heat treatment methods still present the brittle crack path and the research on heat treatments of the metal foam properties is very limited. In this study, individual parameters in stress relieving treatment that contribute to Al-Foam properties were investigated. The stress-relieving process of the samples was performed using a vacuum furnace. The composition of aluminium foam was determined by X-Ray Fluorescence (XRF). The hardness test was conducted using a microhardness tester. Quasi-static compression test was conducted by a universal testing machine. From the SEM-EDX elemental images, it can be observed that traces of Ca, Fe, Ti, and Si have a homogeneous distribution in the Al-matrix. In the result obtained, the mechanical properties of aluminium alloy foam decrease when the heating temperature is enhanced. The mechanical properties of closed-cell aluminium alloy increase with the reduction of the holding temperature. This was due to the recovery and recrystallization process which depended on time and temperature during the heat treatment process. The mechanical properties of aluminium foam were raised after increasing the stabilization temperature. This finding was due to the vibrational atomic motion in the recovery process

Machinability improvement in end milling of Titanium Alloy Ti-6Al-4V through preheating

Titanium alloys are used widely in the aerospace, chemical and ship building industry because of their superior mechanical properties, heat resistance and corrosion resistance. Titanium alloys, however, are materials that are extremely difficult to machine. During the machining of titanium alloy, tool wear progresses rapidly because of the high cutting temperature and strong adhesion between the tool and the work material, owing to their low thermal conductivity and high chemical reactivity [1,2]. However, by properly selecting the tool material and cutting conditions an acceptable rate of tool wear may be achieved and thus lowering the total machining cost [3]. The performance of a cutting tool is normally assessed in terms of its life. Mostly, flank wear is considered, since it largely affects the stability of the cutting wedge and consequently the dimensional tolerance of the machined work surface [4]. The use of workpiece preheating (hot machining) as a technique for improving machining operations has been under consideration since the late 19th century. This was informed by understanding that metals tend to deform more easily when heated, thus enhancing machining. The principle behind hot machining is increasing difference in hardness of the cutting tool and workpiece, leading to reduction in the component forces, improved surface finish and longer tool life [5]. Amin and Talantov [6] studied the influence of the furnace method of preheating of workpiece on machinability of titanium alloy BT6 (Russian Standard) and found that the vertical cutting force component decreases with the increase in the preheating temperature but the radial and the axial components sharply increase to their peak values at a particular temperature. Ozler et al [7] used gas flame heating to improve the machinability of austenitic manganese steel. Wang et al [8] performed LAM using YAG continuous solid laser on Al2O3 particle reinforced aluminum matrix composite (Al2O3p/Al). The result of their study showed that in machining of Al2O3p/Al composite the cutting force was reduced by 30-50 %, tool wear was reduced by 20-30 % in laser assisted machining as compared with conventional cutting. Tosun and Ozler [9]studied hot machining in turning high manganese steels using liquid petroleum gas flame under different cutting conditions of feed rate, depth of cut, cutting speed and surface temperature and developed a mathematical model for tool life from the experimental data using a regression analysis method. The main objective of this study is to investigate the effect of workpiece preheating with high frequency induction heating on improvement of tool life of uncoated WC-Co inserts during end milling of titanium alloy Ti-6Al-4V. Tool wear, vibration, and cutting force were investigated during the experiments

Heat assisted machining of metals and alloys using induction heating method

Settlements in low elevation coastal zone (LECZ) of Bangladesh are exposed to the risk of sea born hazards at present and anticipated sea level rise (SLR) resulting from climate change. This will have serious impact on life and livelihood of coastal community including loss of habitable land. To arrest mass exodus of population, vulnerable community and groups need to be accommodated in places through local level adaptive measure. The present study is, therefore, an attempt to identify key vulnerabilities of coastal community in selected areas with an aim to set criteria for settlement planning and design responsive to climate change in general. Two village communities of Dhulasar union at Kalapara Upazila are selected for socio-spatial analysis of settlement vulnerability. Primary data about socio-spatial profile of the area including settlement pattern and built form, different aspects of vulnerability and present adaptive measures to cope with the risk have been collected from field survey. The study reveals that, the level of vulnerability within same geo-physical exposure is not alike and depends on the degree of community resilience i.e. the capacity of settlement component or community or groups to recover. In addition to the geo-climatic risk, the existing physical and socio economic condition of the dwellers including dispersed settlement pattern, transient nature of houses and poor access to services and shelter makes the coastal community most vulnerable. The study suggests that the vulnerability can be reduced by improving the community or group resilience through planned densification of settlement pattern and management of geomorphology and hydrological process of the context (allow natural siltation, afforestation, improve water drainage, rainwater harvesting etc)

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

Modeling for surface roughness in end-milling of Titanium alloy Ti-6Al-4V using uncoated WC-Co inserts

Titanium alloys are widely known as difficult to cut materials, especially at higher cutting speeds, due to their several inherent properties. Among all titanium alloys, Ti-6Al-4V is most widely used, so it has been chosen as the workpiece material in this study. Siekmann [1] suggested that machining of titanium and its alloys would always be a problem, no matter what techniques are employed to transform this metal into chips. When machining Ti-6Al- 4V, conventional tools wear rapidly because the poor thermal conductivity of titanium alloys resulting in higher cutting temperature closer to the cutting edge. There also exists strong adhesion between the tool and workpiece material [2]. Since the performance of conventional tools is poor in machining Ti-6Al-4V, a number of newly evolved tool materials, such as cubic boron nitride (CBN) and polycrystalline diamond (PCD), are being considered to achieve high-speed milling [3]. In order to establish an adequate functional relationship between the responses (such as surface roughness, cutting force, tool life/wear) and the cutting parameters (cutting speed, feed, and depth of cut), a large number of tests are needed for each and every combination of cutting tool and work piece materials. This increases the total number of tests and as a result the experimentation cost also increases. Response Surface Methodology (RSM), as a group of mathematical and statistical techniques, is useful for modeling the relationship between the input parameters (cutting conditions) and the output variables. RSM saves cost and time by reducing the number of experiments required. A machinability model may be defined as a functional relationship between the input of independent cutting variables (speed, feed, depth of cut) and the output known as responses (tool life, surface roughness, cutting force, etc) of a machining process [4]. Response surface methodology (RSM) is a combination of experimental and regression analysis and statistical inference. RSM is a dynamic and foremost important tool of design of experiment (DOE), wherein the relationship between response(s) of a process with its input decision variables is mapped to achieve the objective of maximization or minimization of the response properties [5-6]. Many machining researchers have used response surface methodology to design their experiments and assess results. Kaye et al [7] used response surface methodology in predicting tool flank wear using spindle speed change. A unique model has been developed which predicts tool flank wear, based on the spindle speed change,provided the initial flank wear at the beginning of the normal cutting stage is known. An empirical equation has also been derived for calculating the initial flank wear, given the speed, feed rate, depth of cut and workpiece hardness. Alauddin et al [8] applied response surface methodology to optimize the surface finish in end milling of Inconel 718 under dry condition. They developed contours to select a combination of cutting speed, and feed without increasing the surface roughness. In this paper, the RSM technique is used in developing a mathematical model to optimize the surface roughness values when end milling titanium alloy using both uncoated WC-Co inserts under dry conditions. Factorial design coupled with response surface methodology is utilized to develop the model for predicting surface roughness values

Comparison of uncoated and coated carbide inserts in end milling of Ti–6Al–4V in terms of surface roughness

This paper compares and also optimizes the surface finish in end milling of titanium alloy Ti-6Al-4V using uncoated and PVD TiAlN coated carbide inserts under dry conditions. Response Surface Methodology (RSM) is utilized to develop an efficient mathematical model for surface roughness in terms of cutting speed, feed and axial depth of cut. For this purpose, a number of machining experiments based on factorial design of experiments method are carried out. The Center Composite Design (CCD) surface roughness models have been developed at 95% confidence level. The adequacy of the models has been verified through analysis of variance (ANOVA). Then the RSM models were further coupled with Genetic Algorithm (GA) to optimize the cutting conditions for getting achievable minimum surface roughness. The GA outcomes were further verified by experimental results. It was found that GA results matched successfully with the experimental data. Uncoated carbide insert was stumbled on as a better option than TiAlN coated carbide in terms of surface roughness

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

Comparison of surface roughness in end milling of titanium alloy Ti-6Al-4V using uncoated WC-Co and PCD inserts through generation of models

Titanium alloys are widely known as difficult to cut materials, especially at higher cutting speeds, due to their several inherent properties. Siekmann [1] suggested that machining of titanium and its alloys would always be a problem, no matter what techniques are employed to transform this metal into chips. When machining Ti-6Al-4V, conventional tools wear rapidly because the poor thermal conductivity of titanium alloys resulting in higher cutting temperature closer to the cutting edge. There also exists strong adhesion between the tool and workpiece material [2]. Since the performance of conventional tools is poor in machining Ti-6Al-4V, a number of newly evolved tool materials, such as cubic boron nitride (CBN) and polycrystalline diamond (PCD), are being considered to achieve high-speed milling [3]. A machinability model may be defined as a functional relationship between the input of independent cutting variables (speed, feed, depth of cut) and the output known as responses (tool life, surface roughness, cutting force, etc) of a machining process [4]. Response surface methodology (RSM) is a combination of experimental and regression analysis and statistical inference. RSM is a dynamic and foremost important tool of design of experiment (DOE), wherein the relationship between response(s) of a process with its input decision variables is mapped to achieve the objective of maximization or minimization of the response properties [5-6]. Many machining researchers have used response surface methodology to design their experiments and assess results. Kaye et al [7] used response surface methodology in predicting tool flank wear using spindle speed change. A unique model has been developed which predicts tool flank wear, based on the spindle speed change, provided the initial flank wear at the beginning of the normal cutting stage is known. An empirical equation has also been derived for calculating the initial flank wear, given the speed, feed rate, depth of cut and workpiece hardness. Alauddin et al [8] applied response surface methodology to optimize the surface finish in end milling of Inconel 718 under dry condition. They developed contours to select a combination of cutting speed, and feed without increasing the surface roughness. Fuh and Wang [9] developed a model for predicting milling force model in end milling operation. They found that the proposed model is suitable for practical engineering application, since the milling force analyzed in the model has already encompassed the structural characteristics of the milling machine and the real conditions of the tool and workpiece. They also suggested that the proposed force model had a good correlation with experimental values. Choudhury and el-Baradie [10] found that response surface methodology combined with the factorial design of experiments were useful techniques for tool life testing. Relatively, a small number of designed experiments are required to generate much useful information that can be used for developing the predicting equation for tool life. Mansour and Abdalla [11] developed a surface roughness model for end milling of a semi-free cutting carbon casehardened steel. They investigated a first-order equation covering the speed range 30 – 35 m/min and a second order generation equation covering the speed range 24 – 38 m/min. They suggest that an increase in either the feed or the axial depth of cut increases the surface roughness, whilst an increase in the cutting speed decreases the surface roughness. Oktem et al [12] used response surface methodology with a developed genetic algorithm (GA) in the optimization of cutting conditions for surface roughness. S. Sharif et al [13] used factorial design coupled with response surface methodology in developing the surface roughness model in relation to the primary machining variables such as cutting speed, feed, and radial rake angle. In this paper, the RSM technique is used in developing a mathematical model to optimize the surface roughness values when end milling titanium alloy using both uncoated WC-Co and PCD inserts under dry conditions. Factorial design coupled with response surface methodology is utilized to develop the model for predicting surface roughness values

Modeling for surface roughness in end-milling of titanium alloy Ti-6AI-4V using uncoated WC-Co and PCD Inserts

This paper presents an approach to optimize the surface finish in end milling titanium-alloy of Ti-6AI-4V using uncoated WC-Co and PCD inserts under dry conditions. Response surface methodology is utilized to develop an efficient mathematical model for surface roughness in terms of cutting speed, feed and axial depth of cut. For this purpose, a number of machining experiments based on factorial design of experiments method are carried out in order to determine surface roughness values. The 3FI surface roughness models have been developed at 95% confidence interval for both the inserts. The adequacy of the models has been verified by analyzing the variance

Development of surface roughness models in end milling titanium alloy Ti-6Al-4V using uncoated tungsten carbide inserts

This paper focuses on developing an effective methodology to determine the performance of uncoated WC-Co inserts in predicting minimum surface roughness in end milling of titanium alloys Ti-6Al-4V under dry conditions. Central composite design of response surface methodology is employed to create an efficient analytical model for surface roughness in terms of cutting parameters: cutting speed, axial depth of cut, and feed per tooth. Surface roughness values were measured using a surface roughness measuring instrument- Mitutoyo Surftest model SV-500. Design of expert package was applied to establish the first order and the second order model and develop the contours. The adequacy of the predictive model was verified using analysis of variance