RESEARCH GAP CONCLUSION AND RECOMMENDATION 70

2.11 RESEARCH GAP

The table 2.2 is show the tool geometry that has been used in the previous research. The factors of tool geometry are influencing the surface roughness during machining process. The factor consists of tool type, tool material, tool diameter, degrees helix, axial rake, radial rake and number of flute. 26 Table 2.2: Tool Geometry Name Tool Material Diameter mm Degrees helix Axial rake º Radial rake º Fluten Yih-Fong and Ming-Der, 2005 End mill TiCN, K10 Co 8, TiN, K20 Co 10, TiAlN E Toolmaterial K30 Co 12 6 30-45 4-10 2-4 Amin et al., 2008 End mill polycrystalline cubic boron nitride PCBN 32 2 Kang et al., 2008 End mill Hybrid coating method Ti–Al–N and Ti–Al– Si–N 2 2 Becze et al., 2000 Ball nose coated carbide roughing, polycrystalline cubic boron nitride PCBN finishing 12.7 0-10 Koshy et al., 2002 Ball nose PVD TiCN, PVD TiAlN, PVD AlTiN 12,16 0-3 +3,-16 2 27 Ning et al., 2001 Ball nose TiAlN 12 30 0-3 Supplier recommended Palbit cutting tool End mill TiAlN 20 2 Pu and Singh, 2013 Ball nose PCBN TiAlN 19 Fallböhmer et al., 2000 Ball end TiN 25.4 Camuşcu and Aslan, 2005 End mill TiAlN TiCN mixed Al 2 O 3 35 2 Liao et al., 2007 End mill TiAlN and TiN 16 20 28 Based on the table 2.3, the machine parameter used by previous researchers consists of cutting speed, feed rate, axial depth of cut, radial depth of cut, material stock, work angle and type of lubricants are listed as a research gap. According to table 2.4, is show the majority finding based on the previous researchers. This literature review contains a result, method and finding based on that research. 29 Table 2.3: Machine Parameter name Speed Vc mmin Feed Fz mmtooth Axial DOC ap mm Radial DOC ae mm material Workpiece angle º lubrication Yih-Fong and Ming-Der, 2005 150-300 0.03-0.05 0.1 0.1 Tool steel Amin et al., 2008 50-150 0.05-0.1 1 AISI D2 tool steel 60-62 HRC Kang et al., 2008 75 0.01 2 0.02 AISI D2 die steel62 HRC Dry, flood coolantWet, MQL Becze et al., 2000 101-1197 0.05-0.1 0.6-1.9 0.2-0.6 D2 63 HRc tool steel Koshy et al., 2002 200-500 0.05-0.1 1 0.5 AISI D2 58HRC Dry cutting Ning et al., 2001 377-1131 0.025-0.05 0.1-0.8 Mold steel H13 55HRC 30 Supplier recommended Palbit cutting tool 140-210 0.1-0.3 0.5-9.0 Pu and Singh, 2013 120-470 0.18 0.12 0.25 AISI A2 at 64 HRC 45 Dry cutting Fallböhmer et al., 2000 150 0.7 0.25 0.75 D2 tool steel 59 HRC Dry cutting Camuşcu and Aslan, 2005 100-200 0.1 0.4 30 AISI D3 steel 35HRC Liao et al., 2007 150-250 0.1-0.2 0.6 5 NAK80 die steel 41HRC dry cutting, flood coolant, and MQL 31 Table 2.4: Findings for previous research AUTHOR FINDINGS Yih-Fong and Ming- Der, 2005 • Apply Taguchi dynamic to construct an optimal high speed Milling with high quality • flank wear has been significantly improved at the optimal conditions • The average surface roughness between the range of 0.2533–0.4833 mm 21-23 HRc and 0.1833–0.3617 mm 17-19 HRc Amin et al., 2008 • Chips producing are composed of primary and secondary serrated teeth • Average flank wear of the tool during preheated machining is found to be slightly higher compared machining at room temperature • Cutting speed, preheating and amplitude of chatter have direct affecting on the surface roughness. • preheated machining of the material influence to surface roughness values well below 0.4 µm Kang et al., 2008 • cutting under flood coolant condition results in the shortest tool life due to severe thermal cracks • MQL leads to the best performance • As the cutting length increased, the tool wear increased proportionally. • In wet condition of the cutting fluid, the tool suffers serious thermal fatigue, and the tool wear rapidly increases compared to the dry and MQL conditions Becze et al., 2000 • The tool failure mode was largely chipping at the lowest cutting speed zone 101 mmin. • D2 tool steel, the tools failed prematurely and repeatedly by extensive chipping in the middle of the length of contact • An average surface finish of 0.3 µm was achieved, increasing to 1 µm at the wall, even with the effect of vibrations present due to the machine dynamics. • The tool life for PCBN at cutting speeds in excess of 1100 mmin was also found to be acceptable. Koshy et al., 2002 • Work piece surface roughness values were in the range 1–6 mm Ra 32 • work piece surface roughness results Ra obtained at various cutting speeds with indexable insert and solid carbide tools, respectively • Work piece surface roughness increased as tool wear progressed, and hence in many applications the roughness rather than the maximum flank wear land width could be the limiting factor that determines tool life. • The roughness obtained with the unworn indexable insert tools was lower than the corresponding values obtained with the solid carbide tools. Ning et al., 2001 • The higher cutting speed and feed rate, the darker color of the chip. Means higher extend of oxidation that leads to a higher temperature. • Different of chip formation is found to be movement of cutting edge under different cutting conditions. Pu and Singh, 2013 • Coated carbide tools are not suitable in the HSM range since it produces the highest Ra value. • the surface roughness from the coated carbide tool increases much more significantly than PCBN • This could be caused by higher cutting forces generated by the coated carbide tool larger cutting edge radius which led to more vibration. • The low content PCBN tool generates higher surface roughness values and is as expected since the chipping and flaking occurred at 32 m cut length • Milling using coated carbide tool at 120 mmin induces more ploughing effects on the workpiece surface which leads to high surface roughness, large hardness increase, dragging of the material, crack initiation and microstructural changes. • Effects on the performance of diemold and also increase the total cost by increasing the difficulty for manual polishing. Fallböhmer et al., 2000 • At V c = 60 mmin tool life was twice as high for PCBN than for TiN coated inserts • Cutting speeds at 550 mmin and more were not practicable under engagement conditions, because the inserts shattered due to overstress 33 Camuşcu and Aslan, 2005 • Work piece surface roughness obtained with coated carbide and cermet tools V c = 100 mmin. • unworn tools produced better surfaces compared with worn tools • Both CBN and TiCN mixed Al 2 O 3 ceramic tools proved to be suitable for high speed end milling of AISI D3 with 35 HRC. • TiAlN is a better coating material than TiCN for the machining applications of hardened tool steels Liao et al., 2007 • MQL was effective especially at low cutting speed for example 75 mmin • MQL is effective as well even when the cutting speed is as high as 250 mmin. The reason of this difference may be due to the tool and the oil of MQL used • the coated carbide tool with higher heat resistance and the oil with a better cooling effect • The temperature is very high in high-speed cutting, which leads to very short tool life • low-speed cutting, the cutting temperature is not high enough to exceed the limitation that the cutting edge can withstand • value of surface roughness rises when the feed rate is increased • At a lower cutting speed such as 150 mmin, the surface roughness in flood cooling is lower than that in dry and MQL cutting • As cutting speed is increased, thermal cracks of the cutting tool become more severe • the surface roughness in dry and MQL cutting decreases as cutting speed is increased 34 The parameter settings used in previous studies are compiled in figure 2.10 and figure 2.11. Figure 2.10: Overview of cutting speed and feed rate in the literature on AISI D2 tool steel. C uttin g s pe ed V c mmin Feed rate fz mmtooth 35 Figure 2.11: Overview on axial and radial depth of cut in the literature on AISI D2 tool steel. A xi al de pt h of c ut a p m m Width of cut, ae mm 36 CHAPTER 3 METHODOLOGY

3.1 INTRODUCTION