Experimental and Simulation Approach; Investigation Effect of Axial Feed Rate to the Cutting Force in Dimple Milling Using Ball End Mill Tool

A recent study indicated that the dimple has potential to improve the parts performance in a way of minimizing friction on a sliding mechanical component. Despite outnumbered dimple fabrication methods, milling process is considered as the versatile process that could produce various dimple profile with complex shape and the process is extremely dependent on the process variable such as machining parameters and cutting tool condition. The present research work aiming to study the effect of the milling machining parameters which is the axial feed rate and tool diameter to the cutting force by means of experimental work and finite element analysis (FEA). The concave dimple profile is machined at different axial feed rate to a flat Al6061 specimen using ball end mill attached to 3-axis CNC milling machine and the cutting force captured by KISTLER force dynamometer and the results will be compared with the FEA results. Based on the results, shows that cutting force increased directly proportional with the increasing plunging feed rates and tool diameters. The investigation work has successfully characterized the influence of studied milling parameters to the cutting forces and the research work will be continued further on the incline milling technique and micro size ball end mill

Using Finite Element simulation to investigate the effect of cutting edge radius on burr formation for inclined dimple milling operation

In any mechanical cutting operation including micromilling, burr formation is unavoidable due to the plastically deformed materials generated from the cutting and shearing phenomenon. Compared to macro milling, the size ratio between burr and micro-milling profile is extremely large making the removal process extremely challenging. Due to the challenge, this paper presents the investigation of critical factors in burr formation such as tool cutting edge radius, Rc using the finite element (FE) approach. The first part of the investigation consists of the validation of the FE simulation results with the experimental by comparing the generated cutting force, and the second part focused on the virtual experiment on the investigation of tool cutting edge radius to the burr formation on the machined dimple profile. In the simulation of inclined dimple milling, the 3D model of solid carbide (WC) ball end mill (BEM) tool contact with the round Aluminum Alloy 6061-T6 specimen model at 45° inclination angle to form the dimple profile and the characteristic of the burr profile measured directly on the deformed specimen model. Based on the results, it was found the cutting edge radius, directly proportional to the cutting force and significantly influence the burr formation in inclined dimple milling

Influence of cutting parameters to surface area roughness in dimple machining using milling process

Surface quality is among the predominant criterion in measuring machining process performance, including milling. It is extremely dependent on the process variable, such as cutting parameters and cutting tool conditions. The main intention of this research work is to study the effect of the milling machining parameters, including depth of cut, spindle speed, feed rate as well as machining pattern to the final surface area roughness of the fabricated dimple structure. The concave profile of the dimple is machined at the right angle to a flat Al6061 specimen using a ball end mill attached to a 3-axis CNC milling machine, and the surface area of the concave profile is measured using 3D measuring laser microscope. It is observed that surface area roughness reacts with the spindle speed and feed rate with different tool sizes. Based on the result gained, the work has successfully characterised the influence of studied milling parameters on the dimple surface area roughness, where within the range of the studied parameter, the surface area roughness varies only less than 2.2 μm. The research work will be continued further on the incline milling technique and micro size ball end mill

Rapid Direct Continuous Method for Hot Embossing of Glass Microlens Array Combined with CO2 Laser Irradiation and External Preheating/Cooling

Hot embossing of glass micro structures requires long thermal cycle, generally takes no less than 15 min due to the isothermal heating, pressing and cooling performed inside a closed vacuum chamber. In this paper, a new hot embossing procedure was presented. First, the glass was preheated slightly below its glass transition temperature at the heating station. Then, a thin layer of the glass surface was further raised to high temperature temporarily through CO2 laser irradiation. The glass was then quickly transferred to the embossing station for pattern transfer, demolding and followed by external cooling. This method accelerated the filling of glass material into the microlens array mold cavities and outperforms the conventional method in terms of overall cycle time reduction, lower mold working temperature and embossing pressure. Microlens array with diameter of 135 µm, sag height of 18.5 µm and pitch of 200 µm were faithfully embossed onto the K-PG375 optical glass time in a time scale of about ~3 s. Optical evaluation of the glass MLA was also performed using charge couple device (CCD) camera which showed uniform spot intensity

Feasibility Study of Wafer Scale Laser Assisted Thermal Imprinting of Glass Nanostructures

Major challenges for any direct nanostructuring method on glass substrate is the difficulty to scale up the patterning area to industrial scale. In this work, a rapid and large area direct thermal imprinting of glass nanostructures using silicon mold assisted by CO2 laser irradiation was demonstrated. Pattern transfer was successful for experiment trial of one spot laser irradiation and laser scanning with imprinting area of 100 mm2 and 400 mm2; confirmed by SEM and AFM measurement. When the method was extended to a larger imprinting area (2000 mm2), the glass was cracked and partially imprinted due to the high cooling rate of the glass after laser irradiation and misalignment of the glass during the contact pressing step in our molding setup

Numerical Model of Heat Transfer Coefficient in Hot Stamping Process

Due to the demands to reducing the gas emissions, energy saving and producing safer vehicles have driven the development of ultra high strength steel. Since the mechanical properties of ultra high strength steel are remarkably high, it has become a major setback for forming process and this has led lead to the development of special forming technique for ultra high strength steel called Hot Stamping. In hot stamping, the ultra high strength steel blank is heated to its austenization temperature of about 900 - 950 ◦C inside the furnace. Then, the heated blank is transferred to the tool where forming takes place and simultaneously quench the blank inside the tool. As the tool dwells, the microstructure of the blank becomes fully martensite thus giving the final part strength of up to 1500 MPa. In order to have a better understanding of the Hot Stamping Process, a numerical model of heat transfer need to be developed to simulate the temperature changes of the blank as well as validate the heat transfer coefficient (HTC) of the blank and tool contact surface as a function of distance and time. The numerical model is based on the heat transfer at the contact surface between the ultra high strength steel blank (Boron Manganese Steel) and the tool made of Tool Steel (SKD11)

Estimation of thermal contact conductance value between boron steel blank and tool surface at different value of applied pressure in hot stamping process

In hot stamping, one of the key factor for successful process control as well as producing a final part strength of more than 1500 MPa is the ability to control heat transfer from the blank throughout the process especially during quenching where the blank need to be cooled down rapidly to transform it’s microstructure into martensite phase. In order to control heat transfer process, a study need to be carried out for understanding the characteristics of heat transfer between two solid bodies in contact to each other and investigates the influence of applied pressure to the heat transfer as well as optimizing its. To do so, a systematic approach has been planned to analyze the heat transfer using finite element analysis (FEA) using commercial simulation software as well as the experimental work. The FEA is done by simulating the heated blank or the specimen cool down as it brought into contact to the tools which has a temperature slightly lower than ambient temperature. The effect of different values of applied pressure is simulates by manipulating the values of thermal contact conductance at the blank and tool surface in contact and the thermal contact conductance values will be simulates ranging in between 1000 to 2000 W/m2K. Meanwhile, the experiment being conducted to measure temperature changes of the blank and tool as it is compress in between a set of experimental tool (upper and lower tool) at different pressure ranging between 5 to 35 MPa. The experiment results will be used to compute the actual thermal contact conductance and compared with the FEA simulation. Based on these analyzed result from both approach, the influence of the applied pressure to the heat transfer between two solid bodies in contact as well as the optimum value of applied pressure possibly defined

Influences of Varying Combination of Feed Rate and Depth of Cut to Tool Wear Rate and Surface Roughness: High Speed Machining Technique in Non-High Speed Milling Machine

Machining technique using high spindle speed, high feed rate and shallow depth of cut utilize in High Speed Milling (HSM) machines offer several benefits such as increase of productivity, elimination of secondary and semi-finishing process, reduce tool load and small chips produced. By adjusting some of the machining parameters, non-HSM machine having lower spindle speed and feed rate could also take advantages some of the benefits mentioned above when applying the HSM technique. This experiment investigate the effects of varying combination of depth of cut and feed rate to tool wear rate and surface roughness during end milling of Aluminum and P20 tool steel in dry condition. The criterion for tool wear before it gets rejected is based on maximum flank wear, Vb of 0.6mm. Material removal rate, spindle speed and radial depth of cut are constant in this experiment. After preliminary machining trials, the combination starts with depth of cut of 2mm and feed rate of 45mm/min until the smallest depth of cut and highest feed rate of 0.03mm and 3000mm/min respectively. The obtained result shows that for both materials, feed rate significantly influences the surface roughness value while depth of cut does not as the surface roughness value keep increasing with the increase of feed rate and decreasing depth of cut. Whereas, tool wear rate almost remain unchanged indicates that material removal rate strongly contribute the wear rate. With no significant tool wear rate, this study demonstrates that HSM technique is possible to be applied in non-HSM machine with extra benefits of eliminating semi-finishing operation, reducing tool load for finishing, machining without coolant and producing smaller chip for ease of cleaning

Comparison of Cooling Performance Between High Thermal Conductivity Steel (HTCS 150) and Hot Work Tool Steel (SKD 61) Insert for Experimental Tool Using Finite Element Analysis

In hot stamping, the tool cooling system plays an important role in optimizing the process cycle time as well as maintaining the tool temperature distribution. Since the chilled water is forced to circulate through the cooling channels, there is a need to find the optimal parameters of the cooling channels that will cool down the tool efficiently. In this research paper, the cooling channel parameters that significantly influence the tool cooling performance such as size of the cooling holes, distance between the cooling holes and distance between the cooling holes and the tool surface contour are analyzed using the finite element method for both static and thermal analysis. Finally the cooling performance of two types of materials is compared based on the optimized cooling channel parameters

Match outcomes prediction of six top English Premier League clubs via machine learning technique

The English Premier League (EPL) is one of the most widely covered league in the world. The prediction of football matches, particularly EPL has received due attention over the past two decades by means of both conventional statistical and machine learning approaches. More often than not, the predictions reported in the literature have rather been dissatisfactory in forecasting the outcome of the matches. This work offers a unique approach in predicting EPL match outcomes, i.e., win, lose or draw by considering top six teams in the league namely Manchester United, Manchester City, Liverpool, Arsenal, Chelsea and Tottenham Hotspur over the span of four consecutive seasons from 2013 to 2016. Fifteen features were selected based on their relevance to the game. Six different Support Vector Machine (SVM) model variations viz. linear, quadratic, cubic, fine radial basis function (RBF), medium RBF, as well as course RBF were developed to predict the match outcomes. A five-fold cross-validation technique was employed whilst, a separate fresh data was supplied to the best model developed in evaluating the predictive efficacy of the model. It was demonstrated from the study that the linear SVM model provided an excellent prediction accuracy of 100 % on both the trained as well as untrained data. Therefore, it could be concluded that the selection of the relevant features, as well as the methodology employed, could yield a reliable prediction of top six EPL clubs match outcomes