Surface Quality of Ti-6%Al-4%V ELI When Machined Using CVD-Carbide Tools at High Cutting Speed

Abstract

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.

Wear Mechanism of Chemical Vapor Deposition (CVD) Carbide Insert in Orthogonal Cutting Ti-6Al-4V ELI at High Cutting Speed

“…Flaking at the rake face and welded material at the flank face were also observed, even the chipping of tool material at the cutting edge. As found by Gusri et al [14] that the depth cut significantly contribute to the cutting time when machining titanium alloy at high cutting speed. As stated by Che Haron [4] that increasing in depth of cut would increase the contact area between the cutting tool and work piece.…”

“…Adhesion or adhering chip the cutting edge of titanium alloy can be seen clearly, demonstrating a strong bound (no evidence of any gaps) at the workpiece-tool interface [11]. Some of them said due to chemical reaction, whereas others argued that was due to crack propagation at the surface interface, which could be due to the difference in the thermal coefficient of expansion between coating matrix and the substrate [11,14]. The adhered or welded titanium will be hit and squashed by the tool, and re-entry to the workpiece, thus leading to the initiation of chipping, flaking and finally to the breakage of carbide at the cutting edge.…”

Tool Wear Performance of CVD-Insert during Machining of Ti-6%Al-4%V ELI at High Cutting Speed

“…It was due to low depth of cut and low feed rate. As stated by Gusri et al [13] that the depth cut significantly contributed to the cutting time when machining titanium alloy at high cutting speed. They also mentioned that machining at high cutting speed and low depth of cut and low feed rate caused wear at nose radius.…”

Machining of Ti-6Al-4V ELI Alloy: A brief review

“…Surface roughness increased with increase in the temperature. Gusri et al [10] investigated the surface quality of Ti-6al-4V ELI alloy using CVD coated insert in the absence of cooling environment. Found that the roughness of the machined surface is more influenced by the feed.…”

“…Surface quality easily affected by the input parameters when machining on titanium alloy specially feed rate is the predominant factor for surface roughness. Due to the high hardness of Ti-6Al-4V ELI alloy and low thermal conductivity, a high amount of heat generated at the upper surface of the workpiece causes increased in the tool wear which damage the microstructure and surface integrity [5][6][7][8][9][10][11][12]. Karkaols et al [5] predicted the surface roughness of Ti-6Al-4V ELI alloy in a milling operation.…”