Grinding force modelling for ductile-brittle transition in laser macro-micro-structured grinding of zirconia ceramics

C/SiC has excellent mechanical properties and is extensively utilized in the aerospace field. Meanwhile, it is a typical intractable material in virtue of its special intrinsic structure. To investigate the grinding force and material removal mechanism of fiber reinforced CMC, a unidirectional C/SiC composite material was designed and prepared. A series of particular surface grinding experiments were carried out, and then the grinding force model was established based on multiple-exponential function method. Furthermore, the surface morphology and grinding mechanism of the composites were analyzed. The results show that the grinding parameters (wheel speed, grinding depth, feed speed) have a significant impact on the grinding force, and the order of grinding force is as follows: Normal>Longitudinal>Transverse. The R2 (Goodness of fit) values of the grinding force model are all above 0.9, which demonstrates the models can reliably predict the grinding force of the unidirectional C/SiC composite grinding. Besides, the dominant removal mechanism of C/SiC composites is the brittle fracture, and its failure modes are the combination of matrix cracking, fiber breakage and interface debonding. Then, the factors affecting the grinding force in surface grinding of the composite are revealed. The research results can provide theoretical support for improving grinding efficiency and precision machining of composites.

Many factors could affect the grinding force during rail grinding processes. Therefore, the grinding force modeling is necessary for predicting the grinding forces under different rail grinding parameter conditions. In this study, 3D models of grinding wheels were constructed based on the surface topographies of real grinding wheels. By means of simulation of rail grinding processes using the DEFORM-3D, the influences of grinding parameters on the grinding forces were explored. Furthermore, in order to verify the simulation results, rail grinding experiments were conducted using a rail grinding friction testing apparatus. Both simulation and experimental results showed that the grinding force increased with the grinding pressure and the granularity of grinding wheel and decreased with the rotational speed of the grinding wheel. A correction factor ks of 0.894 was obtained using the least square method to reduce the error between the simulation and experimental results from 10.22 to 4.42%.

The grinding force was one of the most important parameters, almost related with all the parameters in grinding. In this paper, the grinding force model was established by a new method. The abrasive grains were analyzed using the statistical probability method. The abrasive grains were divided into two types, one was the cutting abrasive grain, and the other was contacting abrasive grain. The force analysis of a single abrasive grain was done. The grinding force model was established on the basis of the statistical probability method and the force analysis of a single abrasive grain. Theoretical analysis was verified by the experiment. The results indicated, the experimental results agree well with the theoretical prediction. The model can accurately predict the grinding force.

There have been few investigations dealing with the force model on grinding brittle materials. However, the dynamic material removal mechanisms have not yet been sufficiently explicated through the grain-workpiece interaction statuses while considering the brittle material characteristics. This paper proposes an improved grinding force model for Zerodur, which contains ductile removal force, brittle removal force, and frictional force, corresponding to the ductile and brittle material removal phases, as well as the friction process, respectively. The critical uncut chip thickness agc of brittle-ductile transition and the maximum uncut chip thickness agmax of a single abrasive grain are calculated to identify the specified material removal mode, while the comparative result between agmax and agc can be applied to determine the selection of effective grinding force components. Subsequently, indentation fracture tests are carried out to acquire accurate material mechanical properties of Zerodur in establishing the brittle removal force model. Then, the experiments were conducted to derive the coefficients in the grinding force prediction model. Simulated through this model, correlations between the grinding force and grinding parameters can be predicted. Finally, three groups of grinding experiments are carried out to validate the mathematical grinding force model. The experimental results indicate that the improved model is capable of predicting the realistic grinding force accurately with the relative mean errors of 6.04% to the normal grinding force and 7.22% to the tangential grinding force, respectively.

Establishment of dynamic grinding force model for ultrasonic-assisted single abrasive high-speed grinding

Ultrasonic vibration assisted grinding is an advanced method for machining difficult-to-process materials such as SiCp/Al composites. This paper presents a mechanics model for predicting grinding forces in ultrasonic vibration assisted grinding of SiCp/Al composites. It consists of side grinding force model and end grinding force model. In side grinding force model, the major components are the normal force and tangential force in which the analytical expressions for the chip formation force based on Rayleigh’s probability density function, the frictional force, and the particle fracture force based on Griffith theory are established, respectively. In contrast, the axial force developed based on the indentation theory is the major component in end grinding force model. The coefficients in the proposed grinding force model were obtained through two groups of orthogonal experiments. Based on the mechanics prediction model, the relationship between grinding forces and process variables were predicted. At last, two groups of single factor experiments were conducted to verify the proposed grinding force model and experimental results were found to agree well with predicted results.

In this study, an analytical grinding force model has been presented for grinding SiCp/Al composites. Different from grinding force model of traditional materials, in this model, three force components are considered, namely chip formation force, frictional force, and fracture force respectively. In order to verify the model and study the special characteristics of grinding SiCp/Al composites, a series of SiCp/Al composite experiments are performed. The theoretical values coincide well with the experimental measurements, which is slightly smaller than the experimental measurements. In addition, the relationship between grinding force and processing parameters is revealed; the variation of grinding force with grinding depth ap and feeding velocity fv is obtained. The relationship between surface roughness and grinding parameters is also found that is similar to the grinding force. By observing the machined surface, a series of surface topography of SiCp/Al composites is found. The surface topography is related with the grinding parameters. The more feeding velocity and grinding depth are, the more uneven surface topography is. Finally, it is found that in the grinding of SiCp/Al composites, a common problem is the formation of voids and delamination on the machined surface, which is due to reinforced particles pulled out and aluminum matrix adhesion on the machined surface.

The grinding force modeling and experimental study of ZrO2 ceramic materials in ultrasonic vibration assisted grinding

Analysis of grinding mechanics and improved grinding force model based on randomized grain geometric characteristics

Heterogeneous components removal mechanism and grinding force model from energy aspect in ultrasonic grinding continuous fiber reinforced metal matrix composites

As grinding force plays an influential role in work-surface finish in grinding process, a model is necessary for optimizing input variables to achieve high product quality and productivity. However, to the best of our knowledge, there are few reports on modeling grinding force in ultrasonic assisted internal grinding (UAIG). In this study, a theoretical model is presented to predict the grinding force in UAIG of SiC ceramics. This model stems from undeformed chip length resulting from the relative motion between the grinding wheel and the workpiece. After analyzing the cutting action of an active individual grain, normal and tangential force models for the UAIG of SiC ceramics are developed. Using the developed model, the influence of many principal input variables, namely the workpiece rotational speed nw, the wheel infeed rate Vc, the wheel rotational speed ng, the UV amplitude Au, and the oscillation frequency fo, on grinding force is predicted. Comparing the predicted forces with the experimental ones, it is shown that the predicted forces agree reasonably well with the experimental ones. The obtained results show that (1) the grinding forces are reduced in the UAIG compared to conventional internal grinding, which is attributed to the formation of the longer undeformed chip length in the UAIG; (2) the influence of ng, nw, and Vc on grinding force are much pronounced, whereas that of Au and fo are not very noticeable; and (3) the force reduction of UV can be enhanced either by decreasing ng, nw, and Vc or increasing Au and fo.

Grinding is an essential gear finishing method. Grinding force analysis and prediction are critical to understand grinding mechanisms. By using a geometry model for gear form grinding and surface grinding mechanisms, a theoretical model was established to calculate the gear form grinding force. By considering the complete tooth depth engagement between tooth grooves and wheel profiles during form grinding, three segments of the involute, transition arc and tooth bottom line, which were included in complete tooth groove profiles, were analysed using the model. Contact relations among the normal grinding depth, wheel equivalent radius, wheel linear velocity and wheel profile were obtained. In addition, grinding experiments were outperformed on the basis of the single tooth, and the unknown coefficients of the form grinding force calculation model were acquired. The effects of the grinding depth, feed speed and grinding speed on grinding force were analysed using the grinding force model. The comparison of the predicted values of the form grinding force model with the experimental results, indicated that the relative errors of tangential and normal grinding forces are within ±10% and ±12%, respectively. The results confirmed the accuracy of gear form grinding force calculation model. These findings play a key role in parameter optimisation during gear form grinding.

In the process of herringbone gear grinding, excessive grinding force leads to a large increase in grinding specific energy. A large increase in the specific grinding energy can easily lead to an increase in the transient cutting load. It leads to grinding burn, tooth surface crack and other undesirable phenomena, which ultimately affect the surface quality and service performance of the workpiece. This paper is based on the contact mechanics of workpiece materials. The number of dynamic effective abrasive particles is considered. Combined with the mechanism of grinding force, the model is developed. Based on the consideration of the wear characteristics of the grinding wheel and the structure parameters of the gear itself, the grinding force model was modified. The accuracy of grinding force model is improved by dividing the effective contact angle of grinding grains into four cases. The experimental results show that the normal grinding force error reaches 10.73% and the tangential grinding force error reaches 10.34%. The model reveals the grinding mechanism, optimizes grinding parameters and improves grinding efficiency. It provides a new way for high-precision machining of aerospace precision herringbone gear.

Grinding force is the key factor in the material removal process, which can vary the efficiency of a grinding machine, surface finish and the tool’s performance or life. This paper presents a grinding force model that accounts for the predominant ploughing force at low depths of cut, along with chip formation force and frictional forces. Computations were carried out on a developed analytical model for total tangential and total normal grinding forces. The model was validated through a surface grinding experiment conducted on IS 103 Cr1 Bearing steel, which has a carbon percentage of 0.55-0.8% and is hardened to 62 HRC, using a developed brazed monolayer Cubic Boron Nitride (CBN) grinding wheel. Experimental coefficients at ploughing, chip formation and friction stage were computed and predicted the total grinding forces. The developed mathematical model of the force demonstrates a strong correlation between predicted and experimental values. The errors of normal tangential grinding force were 10.73% and 17.4%, respectively. The contributions of each force component were extracted from the total normal and tangential force and plotted. The validated experiments confirm the proposed method, which can be effectively used to predict realistic grinding forces. The detailed analysis clarifies the effect of grinding parameters on individual force components like rubbing, ploughing and cutting forces. This method promises valuable insights and its potential into advanced grinding behaviour analysis, focusing primarily on grain scale at micro and miniaturised manufacturing. Major Findings: The study establishes that a comprehensive grinding force model integrating ploughing, chip formation, and frictional mechanisms can accurately predict both total normal and tangential grinding forces. The close agreement observed between experimentally measured forces and model predictions confirms the validity and robustness of the developed mathematical formulation. This strong correlation facilitates effective separation of the total grinding force into its constituent components and enhances understanding of grinding behavior at the grain scale when employing a brazed monolayer CBN wheel on hardened bearing steel.

Predictive modeling of force and power based on a new analytical undeformed chip thickness model in ceramic grinding