Experimental study on the meso-scale milling of tungsten carbide WC-17.5Co with PCD end mills

Abstract

Tungsten carbide is a material that is very difficult to cut, mainly owing to its extreme wear resistance. Its high value of yield strength, accompanied by extreme brittleness, renders its machinability extremely poor, with most tools failing. Even when cutting with tool materials of the highest quality, its mode of cutting is mainly brittle and marred by material cracking. The ductile mode of cutting is possible only at micro levels of depth of cut and feed rate. This study aims to investigate the possibility of milling the carbide material at a meso-scale using polycrystalline diamond (PCD) end mills. A series of end milling experiments were performed to study the effects of cutting speed, feed per tooth, and axial depth of cut on performance measures such as cutting forces, surface roughness, and tool wear. To characterize the wear of PCD tools, a new approach to measuring the level of damage sustained by the faces of the cutter’s teeth is presented. Analyses of the experimental data show that the effects of all the cutting parameters on the three performance measures are significant. The major damage mode of the PCD end mills is found to be the intermittent micro-chipping. The progress of tool damage saw a long, stable, and steady period sandwiched between two short, abrupt, and intermittent periods. Cutting forces and surface roughness are found to rise with increments in the three cutting parameters, although the latter shows signs of reduction during the initial increase in cutting speed only. The results of this study find that an acceptable surface quality (average roughness $R_{\text{a}} < 0.2\,\upmu{\text{m}}$) and tool life (cutting length $L > 600\,{\text{mm}}$) can be obtained under the conditions of the given cutting parameters. It indicates that milling with PCD tools at a meso-scale is a suitable machining method for tungsten carbides.

Keywords

Tungsten carbide / Meso-scale milling / Polycrystalline diamond (PCD) end mill / Cutting force / Surface roughness / Tool wear

References

[1] Ottersbach M, Zhao W. Experimental investigations on the machinability of tungsten carbides in orthogonal cutting with diamond-coated tools. Procedia CIRP, 2016, 46: 416-419.

[2] Zhao W, Yang Q, Khan AM, et al. An inverse-identification-based finite element simulation of orthogonal cutting tungsten carbide. J Braz Soc Mech Sci Eng, 2019, 41: 1-12.

[3] Krain HR, Sharman ARC, Ridgway K. Optimisation of tool life and productivity when end milling Inconel 718TM. J Mater Process Technol, 2007, 189(1/3): 153-161.

[4] Fang ZZ. Correlation of transverse rupture strength of WC-Co with hardness. Int J Refract Met H, 2005, 23(2): 119-127.

[5] Saito H, Iwabuchi A, Shimizu T. Effects of Co content and WC grain size on wear of WC cemented carbide. Wear, 2006, 261(2): 126-132.

[6] Li T, Li Q, Fuh JYH, et al. Effects of lower cobalt binder concentrations in sintering of tungsten carbide. Mater Sci Eng A, 2006, 430(1/2): 113-119.

[7] Liu K, Li XP. Ductile cutting of tungsten carbide. J Mater Process Technol, 2001, 113(1/3): 348-354.

[8] Arif M, Rahman M, San WY. Analytical model to determine the critical conditions for the modes of material removal in the milling process of brittle material. J Mater Process Technol, 2012, 212(9): 1925-1933.

[9] Suzuki H, Okada M, Fujii K, et al. Development of micro milling tool made of single crystalline diamond for ceramic cutting. CIRP Ann Manuf Technol, 2013, 62(1): 59-62.

[10] Nakamoto K, Katahira K, Ohmori H, et al. A study on the quality of micro-machined surfaces on tungsten carbide generated by PCD micro end-milling. CIRP Ann Manuf Technol, 2012, 61(1): 567-570.

[11] Liu K, Li XP, Rahman M. CBN tool wear in ductile cutting of tungsten carbide. Wear, 2003, 255(7/12): 1344-1351.

[12] Zhang J, Suzuki N, Wang Y, et al. Fundamental investigation of ultra-precision ductile machining of tungsten carbide by applying elliptical vibration cutting with single crystal diamond. J Mater Process Technol, 2014, 214(11): 2644-2659.

[13] Tamaki JI, Kubo A, Ullah AS. Wear characteristics of nano-polycrystalline diamond tool in cutting of tungsten carbide. Int J Mechatron Manuf Syst, 2014, 7(4/6): 227-245.

[14] Zhan Z, He N, Li L, et al. Precision milling of tungsten carbide with micro PCD milling tool. Int J Adv Manuf Technol, 2015, 77(9/12): 2095-2103.

[15] Kuppuswamy R, Mkhize N. Near ductile regime machining of tungsten carbide insert through control of cutting speed parameter while using a poly-crystalline diamond tool. Procedia Manuf, 2017, 8: 549-556.

[16] Wojciechowski S, Nowakowski Z, Majchrowski R, et al. Surface texture formation in precision machining of direct laser deposited tungsten carbide. Adv Manuf, 2017, 5(3): 251-260.

[17] Doetz M, Dambon O, Klocke F et al (2018) Process control in ductile mode machining of tungsten carbide. In: The 5th European seminar on precision optics manufacturing, Teisnach, Germany. https://doi.org/10.1117/12.2318709

[18] Sakamoto S, Suwa H, Moriwaki T (2017) Wear properties of diamond-coated ball end tools in milling of tungsten carbide. In: JSME, proceedings of international conference on leading edge manufacturing in 21st century, Hiroshima City, Japan. https://doi.org/10.1299/jsmelem.2017.9.050

[19] Suzuki H, Okada M, Asai W et al (2017) Ultraprecision cutting of silicon carbide using micro milling tool of single crystalline diamond. In: JSME, proceedings of international conference on leading edge manufacturing in 21st century. https://doi.org/10.1299/jsmelem.2017.9.084

[20] Katahira K, Ohmori H, Takesue S, et al. Effect of atmospheric-pressure plasma jet on polycrystalline diamond micro-milling of silicon carbide. CIRP Ann Manuf Technol, 2015, 64(1): 129-132.

[21] Okada M, Yoshida A, Furumoto T, et al. Mechanisms and characteristics of direct cutting of tungsten carbide using a diamond-coated carbide end mill. Int J Adv Manuf Technol, 2016, 86(5/8): 1827-1839.

[22] Minami T, Itoigawa F, Maegawa S et al (2015) Basic study on failure process of CVD diamond coating tool in machining of cemented carbide materials. In: JSME, proceedings of international conference on leading edge manufacturing in 21st century, Kyoto, Japan. https://doi.org/10.1299/jsmelem.2015.8.0522-1

[23] Goel S, Luo X, Comley P, et al. Brittle-ductile transition during diamond turning of single crystal silicon carbide. Int J Mach Tool Manuf, 2013, 65: 15-21.

[24] Yui A, Kitajima T, Krajnik P, et al. Effect of cutting fluid on diamond tool life under micro V-groove turning of cobalt-free tungsten carbide. Adv Mater Res, 2014, 1017: 181-186.

[25] Bian R, Ferraris E, He N, et al. Process investigation on meso-scale hard milling of ZrO₂ by diamond coated tools. Precis Eng, 2014, 38(1): 82-91.

[26] Mia M, Bashir MA, Khan MA, et al. Optimization of MQL flow rate for minimum cutting force and surface roughness in end milling of hardened steel (HRC 40). Int J Adv Manuf Technol, 2017, 89(1/4): 675-690.

[27] Singh G, Gupta MK, Mia M, et al. Modeling and optimization of tool wear in MQL-assisted milling of Inconel 718 superalloy using evolutionary techniques. Int J Adv Manuf Technol, 2018, 97(1/4): 481-494.

[28] Li H, Lai X, Li C, et al. Modelling and experimental analysis of the effects of tool wear, minimum chip thickness and micro tool geometry on the surface roughness in micro-end-milling. J Micromech Microeng, 2007, 18(2): 1-12.

Funding

National Natural Science Foundation of China http://dx.doi.org/10.13039/501100001809(51975289)