Regulating the grinding performance of grinding wheels via mixed granularity of abrasives
Grinding is a machining process which an abrasive grinding wheel (GS, as given in Fig.1) is utilized to remove materials at a certain rotating speed [1]. The grinding wheel is composed of abrasives, binding agent, fillers and pores, etc. In which, the abrasive plays a role of cutting edge during the grinding process. The toughness, strength, fractural behaviors, geometry of abrasive have a significant effect on the grinding performance (grinding capacity, surface integrity of machined workpiece, etc.) of grinding wheel [2, 3].
Fig. 1. The typical grinding wheels with mixed granularity of abrasives.
The strength of zirconia alumina (ZA) with the granularity of F14~F30 was tested. The abrasive contents of F16 or F30 in prepared GS were divided into five grades from high to low: ultrahigh (UH), high (H), middle (M), low (L), and extreme low (EL). It was found that the Weibull crushing strength of F14, F16 and F30 of ZA were 198.5 MPa, 308.0 MPa and 410.6 MPa, respectively, indicating that the strength of ZA grew with the decrease of abrasive grit size. The larger Weibull modulus m indicated a less diversity between the tested particles [4-6]. The m value decreased with the decrease of abrasives grit size, revealing that the diversity between the tested abrasives became larger with the decrease of abrasive grit [7, 8]. Since the defects density of abrasive is constant, the smaller abrasives have the lower amounts of defects and a higher strength, thus making that the finer abrasives were harder to break.
Fig.2. The Weibull characteristic stress σ0 and the Weibull modulus m for different granularities of ZA.
The abrasive comprehensive wear model of the ideal servicing process was developed [9], as illustrated in Fig. 3. Under the ideal conditions, the abrasive has a high utilization rate and the GS exhibits a good grinding performance [3]. Under the given grinding load and binding agent strength, the main wear mechanisms were changed from the attrition wear and micro-facture for the F16 to the attrition wear and pulled-out for the F30 owning to the difference in abrasive crushing strength [10,11]. The attrition wear induced GS degradation and the self-sharpening caused by abrasive pulled-out could achieve an equilibrium state, thus promoting the grinding capacity significantly [9]. For the further development of GS, the abrasive crushing strength, binding agent strength and grinding load, as well as the wear mechanisms evolutions of abrasives, should be adjusted and controlled to promote the abrasives utilization rate.
Fig. 3. The ideal servicing process of an abrasive
Although the grinding performance of GS is influenced by many factors, such as abrasive crushing strength, binding agent strength, grinding load, abrasive cutting behaviors, grinding conditions, etc., the investigations of regulatory mechanisms of mixture granularities of abrasives can supply great reference on the design and manufacturing of GS.
References
- I.Marinescu, M. Hitchiner, E. Uhlmanner, Rowe, I. Inasaki, Handbook of machining with grinding wheel, Boca Raton: Taylor & Francis Group Crc Press (2007) 6-193.
- F. Yao, T. Wang, J.X. Ren, W. Xiao, A comparative study of residual stress and affected layer in Aermet100 steel grinding with alumina and cBN wheels,Int J Adv Manuf Tech 74 (2014) 125-37.
- Li,T. Jin, H. Xiao, Z.Q. Chen, M.N. Qu, H.F. Dai, S.Y. Chen, Topographical characterization and wear behavior of diamond wheel at different processing stages in grinding of N-BK7 optical glass, Tribol Int 151 (2020) 106453.
- Zhao, G.D. Xiao, W.F. Ding, X.Y. Li, H.X. Huan, Y. Wang, Effect of grain contents of a single-aggregated cubic boron nitride grain on material removal mechanism during Ti-6Al-4V alloy grinding,Ceram Int 46(11) (2020) 17666-74.
- F. Ding, J.H. Xu, Z.Z. Chen, Q. Miao, C.Y. Yang, Interface characteristics and fracture behavior of brazed polycrystalline CBN grains using Cu-Sn-Ti alloy,Mat Sci Eng A-Struct 559 (2013) 629-34.
- Shi, L.Y. Chen, H.S. Xin, T.B. Yu, Z.L. Sun,Investigation on the grinding properties of high thermal conductivity vitrified bond CBN grinding wheel for titanium alloy, Mat Sci Eng A-Struct 107 (2020) 1-12.
- Nakata, A.F.L. Hyde, M. Hyodo, H. Murata, A probabilistic approach to sand particle crushing in the triaxial test, Geotechnique49(5) (1999) 567-83.
- Nakata, Y. Kato, M. Hyodo, A.F.L. Hyde, H. Murata, One-dimensional compression behaviour of uniformlygrade sand related to single particle crushing strength, Soils Found 41(2) (2001) 39-51.
- L. Zhang, C.B. Liu, J.F. Peng, etc.Improving the grinding performance of high-speed rail grinding stone via mixed granularity of zirconia corundum. Tribol Int, 2022, 175: 107873.
- L. Zhang, P.F. Zhang, J. Zhang, X.Q. Fan, M.H. Zhu, Probing the effect of abrasive grit size on rail grinding behaviors, J Manuf Process53 (2020) 388-95.
- L. Zhang, C.B. Liu, Y.J. Yuan, P.F. Zhang, X.Q. Fan, Probing the effect of abrasive wear on the grinding performance of rail grinding stones,J Manuf Process 64 (2021) 493-507.