Thermo-mechanical aspects of cutting forces and tool wear in the laser-assisted turning of Ti-6Al-4V titanium alloy using AlTiN coated cutting tools

Abstract

Machining of hard-to-cut materials with conventional processes is still considered as a challenge, as the special properties of these materials often lead to rapid tool wear and reduced surface integrity. For that reason, it is preferable to combine conventional machining processes with other technologies in order to overcome the problems of machining these materials. In the present work, laser-assisted turning experiments on a Ti-6Al-4V workpiece were conducted using AlTiN coated cutting tools in order to investigate the effect of laser heating on cutting forces, cutting temperature, tool wear and microstructure alterations. Two series of experiments were performed under varying cutting speed, laser spot diameter and workpiece diameter values; the first series involved only laser heating of the workpiece and the second both laser heating and cutting. The findings revealed the effect of process parameters on cutting forces and temperature determining the importance of workpiece diameter size, indicated the formation of martensite phase at the top of the heat-affected zone of the workpiece and also showed that high temperatures can lead to intensive tool wear, instead of having a beneficial effect for the cutting tool. Finally, finite element (FE) simulations were carried out in order to study the time evolution of the temperature field and calculate the heating and cooling rates during the process. From the FE results, relatively high heating and cooling rates were observed for smaller workpiece diameters and lower cutting speed, whereas the high magnitude of these rates justified the creation of the martensite phase through a diffusionless transformation.

Hybrid simultaneous laser- and ultrasonic-assisted machining of Ti-6Al-4V alloy

“…This was due to the greater effect of the UAM technology at the lowest range of cutting parameters as discussed in the cutting force section. It is important to note that there is a clear correlation between the reduction of the mechanical loading and the effect on the Ra; this has been observed by other researchers [18][19][20][21][22] for Ti-6Al-4V. Furthermore, the reduction in mechanical loading might have also improved the stability of the cutting operation, and thus enhance the stiffness of the tool.…”

“…In these two investigations, LAM was found to reduce cutting forces and improve surface roughness. In similar experimental LAM work on Ti-6Al-4V, Hedberg et al [20], Habrat et al [21], and Kalantari et al [22] found an improvement in tool wear and residual stresses under certain laser processing and mechanical machining conditions, without significant detrimental effect on microstructure. Feng et al [23] investigated LAM by developing an analytical model to predict residual stresses, where they considered the recrystallisation of the material due to the exposure to the laser beam.…”

Nontraditional energy-assisted mechanical machining of difficult-to-cut materials and components in aerospace community: a comparative analysis

“…Owing to the advantages of lasers in terms of energy concentration, fast processing, good controllability, and high accuracy, laser-assisted mechanical machining has become a research hotspot [115][116][117][118][119][120][121]. Laser-assisted mechanical machining is a hybrid process that uses a laser to reduce the physical/mechanical properties of materials or to modify the phase/microstructure of local materials to improve machinability.…”

Effect of Cutting Fluid on Machined Surface Integrity and Corrosion Property of Nickel Based Superalloy

“…As a typical difficult-to-cut material, the superalloy used for these key components usually has good comprehensive properties, such as high strength, corrosion resistance, and fatigue resistance. In the machining of such hard-to-cut alloys, high cutting temperature, serious tool wear, poor quality, and other problems are often improved by various auxiliary machining methods, such as nitrogen [ 1 ], CO 2 [ 2 ], and cooling machining, by reducing the cutting temperature to improve the surface quality [ 3 ], while the laser-assisted cutting method reduces cutting force but accelerates tool wear [ 4 ]. MQL lubrication improves surface quality, while reducing tool wear and cutting temperature, due to cooling and local lubrication of the cutting zone [ 5 ].…”