Effect of Tool Coating and Cutting Parameters on Surface Roughness and Burr Formation during Micromilling of Inconel 718

Abstract

Surface roughness and burr formation are among the most important surface quality metrics which determine the quality of the fabricated parts. High precision machined microparts with complex features require micromachining process to achieve the desired yet stringent surface finish and dimensional accuracy. In this research, the effect of cutting speed (m/min), feed rate (µm/tooth), depth of cut (µm) and three types of tool coating (AlTiN, nACo and TiSiN) were analyzed to study their effect on surface roughness and burr formation during the micromachining of Inconel 718. The analysis was carried out using an optical profilometer, scanning electron microscope and statistical technique. Machining tests were performed at low speed with a feed rate (µm/tooth) below the cutting-edge radius for 10 mm cutting length using a carbide tool of 0.5 mm diameter on a CNC milling machine. From this research, it was determined that the depth of cut was the main factor affecting burr formation, while cutting velocity was the main factor affecting the surface roughness. In addition, cutting tool coating did not significantly affect either surface roughness or burr formation due to the difference in coefficient of friction. The types of burr formed during micromilling of Inconel 718 were mainly influenced by the depth of cut and feed rate (µm/tooth) and were not affected by the cutting velocity. It was also concluded that the results for the surface finish at low-speed machining are comparable to that of transition and high-speed machining, while the burr width found during confirmation experiments at low-speed machining was also within an acceptable range.

Cost and Quality Optimization Taguchi Design with Grey Relational Analysis of Halloysite Nanotube Hybrid Composite: CNC Machine Manufacturing

“…This, in turn, would lead to a rough application of the cutter on the workpiece, thereby leading to a lot of surface roughness. This finding is in agreement with the literature [50,51,[54][55][56]. The depth of cut, however, geometrically increased the surface roughness at 0.8 mm depth of cut.…”

Tool Wear Analysis during Ultrasonic Assisted Turning of Nimonic-90 under Dry and Wet Conditions

“…However, the CT under dry conditions shows better results between durations of 45s and 65s. This can be attributed to built-up edge formation in the CT under dry conditions, as shown in Figure 5 and Figure 6, which may reduce the contact between the tool and the workpiece and reduce the VBb [35]. At the end of machining, the size of the built-up edge may reduce, increasing the contact between tool and workpiece, which increases the VBb.…”

“…However, a small crater, built-up edge and chipping of the cutting edge are observed. The crater is mainly due to the chemical affinity of Nimonic-90 and tools [34,35]. A high temperature near the cutting edge imposes the welding between chip and tool even in the UAT, leading to the built-up edge and chipping adhesion.…”

Optimization of AlCrSiWN Coating Process Parameters and Performance Study by the Matrix Analysis Method

“…Jing et al [ 13 ] investigated the performance of AlTiN-based composite coatings in dry end milling of hardened steel and found that AlTiN-based composite coatings performed well in reducing cutting forces, preventing adhesive wear and isolating cutting heat and were suitable for dry milling of hardened SKD11. It is possible to reduce surface roughness and improve surface quality using coatings by optimizing the coating film thickness [ 14 ] and cutting parameters [ 15 ]. The coating performance is influenced by process parameters such as bias voltage [ 16 ], arc current [ 17 ], substrate temperature [ 18 ] and gas flow rate [ 19 ] in the preparation of multi-layer composite coatings by arc ion plating process.…”