Machinability of Titanium Alloys in Drilling

As is recognised widely, tool wear is a major problem in machining of difficult-to-cut titanium alloys. Therefore, it is of significant interest and importance to understand and determine quantitatively and qualitatively tool wear evolution and the underlying wear mechanisms. The main aim of this paper is to investigate and analyse wear, wear mechanisms along with surface and chip generation of uncoated and TiAlN coated carbide tools in a dry milling of Ti6Al4V alloys. Quantitative flank wear and roughness were measured and recorded. Optical and SEM observations of tool cutting edge, machined surface and chips were conducted. Results show that the TiAlN coated tool exhibits approximately 44% longer tool life than the uncoated tool at a cutting distance of 16 m. A more regular progressive abrasion between the flank face of tool and workpiece is found to be the underlying wear mechanism. The TiAlN coated tool generates smooth machined surface with a 31% lower roughness than the uncoated tool. As is expected, both tools generate the serrated chips; however, burnt chips with blue colour are noticed for the uncoated tool as the cutting continues further. The results are shown to be consistent with observation of other researchers, and further imply that the coated tools with appropriate combination of cutting parameters would be able to increase the tool life in cutting of titanium alloys.

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“…Moreover, the findings are quite consistent with those of other researchers, e.g. [21], [22]. as seen in Fig.…”

Section: Cutting Toolssupporting

confidence: 93%

Comparative study between wear of uncoated and TiAlN-coated carbide tools in milling of Ti6Al4V

et al. 2017

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“…Drilling of titanium is one of the most complex processes in the production of aircraft structures. Ti alloys have been reported as difficult to cut materials owing to their particular physical properties [12][13][14]. On the one hand, their low thermal conductivity (about 15 W/m K versus 270 W/m K for the steel CRS1018 at 700 • C) [15] leads to high temperatures in the cutting zone.…”

Section: Introductionmentioning

confidence: 99%

“…Previous studies have thoroughly analysed the effect of cutting parameter variation in the cutting forces and the resulting hole quality. Sharif et al [14], for example, evaluated the performance of both uncoated and coated tungsten carbide drills at various cutting speeds. They observed that the average surface roughness value (Ra) decreased by approximately 20% by doubling the cutting speed.…”

Section: Introductionmentioning

confidence: 99%

“…This rise of cutting forces can be explained by the direct relationship between the feed and the cross-sectional area of the undeformed chip. The evolution of cutting forces was also investigated in the work of [14]. In this case, lower torque values were observed when increasing the cutting speed; this result was attributed to the reduction of the material hardness as the temperature increased.…”

Section: Introductionmentioning

confidence: 99%

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Experimental Investigation of the Influence of Wire Arc Additive Manufacturing on the Machinability of Titanium Parts

Alonso

Veiga

Suárez

et al. 2019

Metals

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The manufacturing of titanium airframe parts involves significant machining and low buy-to-fly ratios. Production costs could be greatly reduced by the combination of an additive manufacturing (AM) process followed by a finishing machining operation. Among the different AM alternatives, wire arc additive manufacturing (WAAM) offers deposition rates of kg/h and could be the key for the production of parts of several meters economically. In this study, the influence of the manufacturing process of Ti6Al4V alloy on both its material properties and machinability is investigated. First, the mechanical properties of a workpiece obtained by WAAM were compared to those in a conventional laminated plate. Then, drilling tests were carried out in both materials. The results showed that WAAM leads to a higher hardness than laminated Ti6Al4V and satisfies the requirements of the standard in terms of mechanical properties. As a consequence, higher cutting forces, shorter chips, and lower burr height were observed for the workpieces produced by AM. Furthermore, a metallographic analysis of the chip cross-sectional area also showed that a serrated chip formation is also present during drilling of Ti6Al4V produced by WAAM. The gathered information can be used to improve the competitiveness of the manufacturing of aircraft structures in terms of production time and cost.

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“…The rubbing action provides high cutting pressure which causes the workpiece to tend to move away from the cutting tool. In addition, a freshly cut surface may be burnished by a dull cutting tool, and hence work-hardened at the machined surface [23].Furthermore, extreme undissipated heat generated at the cutting edge encourages the accumulation of sheetmaterial on the tool surface. This process is usually known as galling and is related to adhesion wear.…”

Section: Results and Discussion Surface Finishmentioning

confidence: 99%

Surface Finish when Threading Titanium-Based Alloy under Dry Machining

Hamdan¹,

Yasir²,

Saïd³

et al. 2014

J MECH ENG SCI

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This paper discusses the quality of surface finish when threading titanium-based alloy under dry condition. The quality of surface finish was studied at various cutting parameters and at the two extreme stages of the machining process, i.e. at the beginning and end of the process. The objective is to evaluate the effect of a worn-out tool on the quality of surface finish. PVD-coated carbide tools were used in this study. Experiments were conducted at two cutting speeds, 35 and 55 m/min, two depths of cut, 0.2 and 0.25 mm, and a constant pitch of 2.0 mm. The tool wear and the quality of surface finish were inspected visually by microscope. The tool's flank wear was measured gradually and machining was stopped when the flank wear reached the rejection criterion of0.3 mm. The microstructure beneath the machined surface was also evaluated. It was found that, at the beginning of machining, there was only a feed mark on the surface finish. When the machining was prolonged until the tools reached the rejection criterion, a bad surface finish was produced. Metal debris, surface cavities and a boundary crack were observed. Results show that machining with a worn-out tool can cause microstructure alteration beneath the machined surface. The selection of cutting parameters and monitoring of tool wear are crucial in order to obtain a good surface finish. Characterization of the surface finish with respect to the threading process under a dry condition would ultimately help in the development of suitable parameters for machining titanium-based alloys.

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Machinability of Titanium Alloys in Drilling

Cited by 28 publications

References 40 publications

Comparative study between wear of uncoated and TiAlN-coated carbide tools in milling of Ti6Al4V

Comparative study between wear of uncoated and TiAlN-coated carbide tools in milling of Ti6Al4V

Experimental Investigation of the Influence of Wire Arc Additive Manufacturing on the Machinability of Titanium Parts

Surface Finish when Threading Titanium-Based Alloy under Dry Machining

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