Machining of Ti-6Al-4V ELI becomes more interested topic due to extremely weight-tostrength ratio and resistance to corrosion at elevated temperature. Quality of machined surface is presented by surface roughness, surface texture and damages of microstructure of titanium alloys. The turning parameters evaluated are cutting speed of 55 -95 m/min, feed rate of 0.15 -0.35 mm/rev, depth of cut of 0.10 -0.20 mm and tool grade of CVD carbide tools. The results show the trend lines of surface roughness value are higher at the initial machining and the surface texture profile has a strong correlation with the feed rate. At the machining condition of cutting speed of 95 m/min, feed rate of 0.35 mm/rev and depth of cut of 0.10 mm produced the with layer with thickness of 2.0 µm.

This paper reports the results of an experimental works, where Inconel 718, a highly corrosive resistant, nickel-based super alloy, was finish-turning under high speed conditions. The machining processes were carried out at three different cutting conditions (DRY, MQL 50 ml/h and MQL 100 ml/h), three levels of cutting speed (Vc=90, 120 and 150 m/min), two levels of feed rate (f=0.10 and 0.15 mm/rev) and two levels of cutting depth (d=0.30 and 0.50 mm). The tool wear and flank wear progression were monitored, measured and recorded progressively at various time intervals. The experiments indicated that MQL condition performs better than dry condition in term of tool life. Most of the tool failures during machining were due to gradual failure where abrasive and notching wear on the flank face was the dominant followed by, fracture on the flank edge and nose radius. Tool failure due to crater wear was not significant. Wear mechanism such as abrasive and adhesion were observed on the flank face and diffusion wear was observed on the rake face.

The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of Minimum Quantity of Lubricant (MQL) under transient cutting speed before advancing to high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V using Physical Vapor Disposition (PVD) coated cemented carbide tools. The machinability studied parameters were the generated cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition under dry and near dry (or MQL) machining. For near dry machining, two levels of coolant flow rate of 50 and 100 mL/H were investigated. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more effective at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. The effect of the cutting speed and coolant flow rate on the surface roughness is not significant. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of MQL on cutting force at early stage of machining was observed. MQL seems to be more effective when tools start to wear out, where greater contact area between tool and work piece occurs to give better lubrication effect.

The effectiveness of the usage of coolant in high speed machining of highly reactive material like titanium and its alloys is still far away uncertain. For this reason, it is wiser to study the effectiveness of MQL under transient cutting speed before we go to the high speed machining. This paper discusses the effect of MQL on the machinability of Ti-6Al-4V by using PVD coated cemented carbide tools. The machinability of Ti-6Al-4V was investigated based on the effect on cutting force and the tool life. The performance of PVD coated cemented carbide tool was investigated at various cutting condition. Completely dry machining and near dry (MQL) were applied in this experiment. For near dry machining, two levels of coolant flow rate were investigated, 50 and 100 mL/H. The effectiveness of mist coolant was tested at three different levels of cutting speed, 120, 135 and 150 m/min. Application of mist coolant is more significant at cutting speed of 135 m/min. At this speed longer tool life was obtained when more coolant was applied. No significant effect of the cutting speed and coolant flow rate on the surface roughness. Surface roughness is more sensitive to the feed rate and the depth of cut. No significant effect of application of MQL on cutting force at early stage of machining. MQL seems to be more affective when tools start worn out where greater contact area between tool and work piece occur to give better lubrication effect.

The performance of Chemical Vapor Deposition (CVD) carbide insert with ISO designation of CCMT 12 04 04 LF, when turning titanium alloys was investigated. There were four layers of coating materials for this insert i.e.TiN-Al2O3-TiCN-TiN. The insert performance was evaluated based on the insert's edge resistant towards the machining parameters used at high cutting speed range of machining Ti-6Al-4V ELI. Detailed study on the wear mechanism at the cutting edge of CVD carbide tools was carried out at cutting speed of 55 -95 m/min, feed rate of 0.15 -0.35 mm/rev and depth of cut of 0.10 -0.20 mm. Wear mechanisms such as abrasive and adhesive were observed on the flank face. Crater wear due to diffusion was also observed on the rake race. The abrasive wear occurred more at nose radius and the fracture on tool were found at the feed rate of 0.35 mm/rev and the depth of cut of 0.20 mm. The adhesion wear takes place after the removal of the coating or coating delaminating. Therefore, adhesion or welding of titanium alloy onto the flank and rake faces demonstrates a strong bond at the workpiece-tool interface.