Abstract: This research characterizes flow of micromist for machining purpose. Liquid lubricant with contact angle less than 5° is chosen for best wetting on workpiece and tool materials. A high nozzle air speed of 100 m/s produces micromist with 20° spherical cone angle containing droplets of 4 μm average diameter, but smaller droplets might raise an environmental concern. Preliminary comparative tests show a significant reduction of tool wear when machining 4140 steel in minimum quantity lubrication.
Abstract: Cutting temperature generated during high speed machining operations has been recognized as major factors influence tool performance and workpiece geometry. This paper aims to model the cutting temperature and to investigate cutting temperature behaviours when contour-in tool path strategy applied in high speed end milling process. The experiments were carried out on CNC vertical machining center by involving PVD coated carbide inserts. Cutting speed, feed rate and depth of cut were set to vary. Results obtained indicate that cutting temperature is high in the initial stage of milling and at the corners region or turning points region. Portion of radial width of cut with workpiece in combination with the abrupt change of the milling path direction occur particularly in acute internal corners of a pocket leads to rise of cutting temperature.
Abstract: Soda lime glass is used extensively in camera lens, micro gas turbines, light bulbs, tablewares, optics, and chemical apparatus owing to its high hardness, excellent optical properties, and good corrosion and chemical resistance. Such applications of soda lime glass demand high machining and finishing precision. On the other hand, machining of glass poses significant challenges due to its inherent brittleness. The process of removal of material from glass, if not done in ductile mode, can generate subsurface cracks and brittle fractures which have adverse effects on its functionality. This research investigates the high speed micro-end milling of soda lime glass in order to obtain ductile regime machining. It has been found by other researchers that ductile mode machining can avoid sub-surface cracks and brittle fractures. However, in ductile mode machining, the gummy chips settle permanently on the machined surface affecting adversely the surface finish. In order to avoid such chip settlement, compressed air was directed using a special air delivery nozzle to blow away the resultant gummy chips, thereby preventing them from settling on the machined surface. Response surface methodology (RSM) and a commercial NC end mill were used to design and perform the machining runs, respectively. Machining was done using: high spindle speeds from 30,000 to 50,000 rpm, feed rates from 5 to 15 mm/min, and depth of cuts from 3 to 7 μm. Three different diameter carbide tools were used: 0.5, 1, and 2 mm. A surface profilometer was used to analyze the surface roughness of the resultant machined surface. Subsequently, the data was used for finding the best combination of cutting parameters required to obtain the lowest surface roughness. The results demonstrate that high speed machining is a viable option for obtaining ductile regime machining and generating machined surfaces with very low surface roughness in the range of 0.08μm – 0.22 μm, using 0.5 mm carbide end mill cutter.
Abstract: The cutting force is the main important factor contributing the machined work piece surface and in determining the acceptable cutting parameters for high productivity in metal cutting industries. The prediction of cutting force coefficients of materials were calculated from the average cutting force model contributing to the constants of cutting force coefficients. In this study, experimental investigation is conducted to determine the cutting force coefficients in the average cutting force model, by identifying cutting force coefficients with different lubrication conditions such as dry, flood and minimal lubrication conditions and cutting speeds. A series of slot milling experiments are measured the milling forces by fixing the spindle speeds and radial/axial depths of cutting and linearly varying the feed per tooth. Using linearly fitting the experimental data, the tangential and radial milling force coefficients are then computed. The achieved results showed that the changing of spindle speed and different lubrication conditions affecting the milling force coefficient.
Abstract: The paper reports the research on the improvement of tool wear resistant of Titanium Carbide (TiC) cutting tool after microwave post sintering treatment. Titanium Carbide square milling insert was microwave sintered at 600°C with 15 minutes of holding time. The face milling operations were conducted to Carbon Steel S45C block (130 mm x 95 mm x 40 mm) by using both of original and microwave sintered insert at 5 different cutting speed (60, 90 , 120 , 150 and 180 m/min), constant feed rate (0.2 mm/tooth) and constant depth of cut (0.2 mm/tooth). The flank wear of the insert was measured every nearest 10th minute of complete cutting passes. The results of the experiment show that microwave post sintering treatment improves the tool resistant of the TiC insert. The flank wear of the sintered insert is lower at any machining time and all cutting speed. The research also found that the percentage of the improvement is lower at higher cutting speed compare to lower cutting speed.
Abstract: This paper presents the investigation of the influence of machining parameters on delamination at entry of drilled holes after drilling into CFRP composite using 4 mm-diameter 2-fluted carbide drills coated diamond. The delamination at tool entry was analyzed in terms of delamination factor on the basis of analysis of variance (ANOVA) of Central Composite Design (CCD) of experiments. It is found that spindle speed is the most influential factor for the drilling of CFRP within the range of cutting parameters examined. The lowest delamination factor (1.006) was generated at rotational speed, 4400 rpm and feed rate, 270 mm/min; and the highest delamination factor (1.123) generated at rotational speed, 537 rpm and feed rate, 180 mm/min. A mathematical model has been predicted for the delamination at tool entry. The relationship between the machining variables and output variables is also established.
Abstract: The aim of the present study is to investigate the influence of cutter engagement on cutting forces in end milling process of AISI H13 (48 HRc). The experiments were carried out on CNC vertical machining center. The machining conditions are as follows: Vc = 150, 200 and 250 m/min, fz = 0.05, 0.1 and 0.15 mm/tooth; a = 0.1, 0.15 and 0.2 mm for every cutting process. Central Composite Design with 20 runs was employed. Data analysis showed that cutter engagement influence the cutting force for the end milling process of hard material H13 in the same pattern to the similar experiment of different material. The present study of cutter engagement will be useful in tool path creation which is important for mold and die machining. The cutter engagement study related to cutting force in high speed end milling of AISI H13 has not yet been established. This study will help the NC programmers in choosing the suitable tool path that will give stable, productive, and more efficient milling process
Abstract: As the tendency towards weight reduction and low fuel consumption seems to drive the increased use of advanced exotic materials such as composites, titaniums and Inconels in the aerospace industry, the need for machining remains in aircraft industries as a post-processing operation. In the present work, the investigation of the influence of machining parameters on surface temperature when drilling CFRP using 4 mm-diameter 2-fluted carbide end-mill coated with diamond is presented. The temperature was examined on Thermal Gun Quicktemp 860-T1 sensor and analysed based on analysis of variance (ANOVA) of Central Composite Design of experiments and a first order mathematical model has been developed to predict temperature values for range of machining parameters used in the study. The relationship between the machining variables and output variables is established. It was found that the lowest temperature (32.2°C) was generated at rotational speed, 537 rpm and feed rate, 180 mm/min and at the highest temperature (39.1°C) generated at rotational speed, 4400 rpm and feed rate, 270 mm/min.
Abstract: : The investigation of the influence of machining parameters on delamination at exit of drilled holes after drilling into CFRP composite using 4 mm-diameter 2-fluted carbide drills coated diamond is present in this paper. The delamination at tool exit was analyzed in terms of delamination factor on the basis of analysis of variance (ANOVA) of Central Composite Design (CCD) of experiments. It is found that spindle speed is the most influential factor for the drilling of CFRP within the range of cutting parameters examined. The lowest delamination factor (1.003) was generated at rotational speed, 5063 rpm and feed rate, 180 mm/min; and the highest delamination factor (1.093) generated at rotational speed, 537 rpm and feed rate, 180 mm/min. A mathematical model has been predicted for the delamination at tool entry. The relationship between the machining variables and output variables is also established.
Abstract: In pocketing operation for mold and die, the variation of tool engagement angle causes variation in the cutting force and also cutting temperature. The objective of this study is to investigate the effect of tool engagement on cutting temperature when using the contour in tool path strategy for different cutting speeds. Cutting speeds of 150, 200 and 250m/min, feedrate from 0.05, 0.1, 0.15 mm/tooth and depths of cut of 0.1, 0.15 and 0.2 mm were applied for the cutting process. The result shows that by increasing cutting speed, the cutting temperature would rise. Varying the tool engagement also varied the cutting temperature. This can be seen clearly when the tool makes a 90o turn and along the corner region. Along the corner, the engagement angle varies accordingly with the radial depth of cut.